Wet May will give way to humidity and summerlike temperatures as we enter June

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After a very active May, the weather pattern slows down and warms up as we enter June.  Cloudy grey skies over the weekend will clear on Monday and we’ll start on a cool note, before temperatures and the humidity  rise mid week and beyond.  Be sure the A/C is working as we’re going to be needing it after Wednesday.  Highs in the low-mid 80s and lows in the 65-70 degree range are expected. Rain chances will be much more scattered, and they will be tied to thunderstorm clusters which form on the Front Range each afternoon and track east and southeast each night.  Right now, that train of storm clusters is likely to run from MT/WY/CO through the Dakotas into NE/MN and IA, but these may trend a little further south than forecast right now.  This will be one of those typical mid summer patterns where these clusters roll off the high terrain in the evening and whatever’s left over approaches or passes through overnight or in the morning.  That’s more likely for us late in the week, while early in the week, we will likely see periods of high clouds (blowoff from the distant storms) mainly each morning and early afternoon, so 100% sunny days all week are not anticipated either, but at least we’ll have at least the first half of the week rain-free.  No organized or major severe weather outbreaks are anticipated either, as those will be mainly near where the storms form along the front range.  Late this week there will be the potential for some of the clusters to give us some gusty winds if they remain strong enough as they reach our area.

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May in Review:

Most notable for May was the rainfall.  The western district had 7-11″ of rain, with Kansas City International reporting the sixth wettest May on record with 10.25″ of rainfall.  10.29″ marked the 5th wettest May in 1996.  Additionally, there has not been 10″ of rain reported at KCI since June, 2005, which was just one month shy of 10 years ago. This puts KCI just under 3″ above average for 2015 and over 5″ above average for May.

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The rain in the western district was the northernmost tip of a heavy rain area which extended and expanded SSW:

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10-20″+ fell over OK/TX making news with devastating flooding.

The eastern district saw significant rainfall as well, especially SEMO/SW IL, but STL finished the month nearly 1″ below average and is now nearly 1″ below average for 2015.

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This series of maps (click to make more readable) show average May rains (L), percent of average observed rains (M) and difference from average observed rains (R).

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This extraordinary rainfall has pretty well wiped out the multi-year central and southern Plains drought.  Lingering dryness is spotty over TX/KS/OK.

 

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But this is a big difference when compared with 1 year ago:

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This map shows the change from this time in 2014.  Yellows/oranges show worse-off locations while greens show improvement.

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Wet areas this month stayed cool with drier areas seeing warmth this month.

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The US NWS CPC expects higher probabilities for a cooler than average June centered on the south central Plains, with a ring of warmth from the west, through the north and along the east coast.  The cooler than average weather is in part due to the fact of this being very wet ground and a lot of the sun’s energy will go into evaporation rather than heating even without additional heavy rains.

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While a signal for wetness remains across the Southern Plains, the stronger signal shifts northward to the CO/NE area and along the southern and eastern coasts.  Locally, this forecast shows little signal for wet or dry.  Other forecasts are for more widespread wetter conditions.  June rains are largely dependent upon where storm clusters form and track and as we’ve seen, some areas can be inundated while other areas not that far away miss out.

Global Tropics:

Western Pacific:

Super Typhoon Dolphin

Dolphin developed at low latitudes and was most notable for passing just north of Guam. This image was taken several days after the system had passed through the Marianas Islands (Guam is the larger island to the southeast of the eye.  The system was near peak intensity in this image.

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TY Dolphin passed through the range of the Guam Radar with these series of images taken (Click to make more readable). The B&W image shows the subtle structure of the rain bands while the 3-D images also show some of the structure.  The red/blue image shows the wind field (speed) with blues winds blowing inbound and red winds outbound.

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Eastern Pacific:

Hurricane Andres (01E)

Andres wasted no time forming from a tropical wave along 100W south of Mexico at the end of May (the East Pacific season opens 5/15).  This series shows the system as it organized and neared peak.  As with most eastern Pacific tropical cyclones, the system moved well offshore and well away from any land areas.  As the month ended, it was approaching colder waters and will rapidly weaken the first week of June.

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Tropical Low 93E formed right behind Andres and was visible as a tight swirl of clouds.  Wind shear from Andres was preventing development, but as that system weakens, this one will strengthen and according to the NHC is likely to become a tropical depression early  this week, as a Tropical Storm, it would be named “Blanca”.  This looks to be a very busy tropical cyclone season in the central and eastern Pacific.

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We’ll follow up with the progress of these two systems in later posts.

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Warmth and humidity return this week, “best” rain chances west until late week.

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A Summertime preview is in store this week as highs climb into the high 70s and low 80s.  Humidity will be back in force as well.  The west will see periodic clouds and shower/storm chances all week, peaking late week, while the east sees more sun and better rain chances hold off until late week or next weekend.

Drought Update:

Little rainfall brought little change to the map, but dryness is gaining hold again in the western district with most of the week’s rain falling west and south over parts of TX/OK and W KS which are in really bad shape. They should see some significant improvement in next week’s update.  Three days in and KC is already a half an inch below average in rainfall.  May and June are the year’s wettest months when 5.23″ of rain falls on average each month.  2015 deficits are nearing 3″. By contrast, St. Louis is only 0.55″ behind for 2015.

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This week’s rainfall potential holds some real hope for the western district, and a real chance for a bust. As you can see there is a very sharp dividing line between very little rain east and several inches west.  Remember, these are generalized totals and even within the “forecast” rain bands there will be lucky locations which get lots of rain and those who just by chance, miss the significant showers.  The threat would be a westward shift in the expected rain, which would give the central Plains the heaviest totals and keep those totals..just..out of reach for the west.  The west needs about 1.25″ of rain per week this time of year just to keep up with average.

Here’s the rainfall outlook graphic:

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Severe Weather:

There will be a non-zero risk for severe storms this week, but pinpointing one day over another is virtually impossible this week, there is no “overall” strong signal for severe weather. That being said, the central and southern Plains will have the greatest risk, with a few days with a marginal risk into the west.  It will all depend upon where the storm clusters form, where they track and how much cloudiness they leave behind. Later in the week as a larger system comes out of the SW U.S, there may be a potential for more widespread strong storms, but that may not happen until next weekend.  Overall, we’re in for a week with few 100% sunny days out west (more partly cloudy to cloudy at times) and periodic chances for showers and storms, while there will be more sun in the east and rain chances really stay away until late week.  One thing for certain: You’ll feel the humidity return as highs climb into the 70s and low 80s and lows remain 60 or higher over the entire district.

Week in Review:

As expected, a very quiet week across the district with a few showers across the western district on Saturday morning.  Here are the rainfall charts for the seven-day period ending today for both districts:

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Looking back at April:

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April was a mild month for most of the country, the heat out west faded a bit and the cold in New England did as well. The cold was mainly centered near the still-cold Great Lakes, northern New England and the Rio Grande Valley, with isolated pockets elsewhere. Florida and the Gulf Coast was the warmest.

Rainfall in the west was heaviest south and east of KC and much lighter N and W.

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The eastern district fared better, as has been the case for a while now, with the heaviest totals following the tracks of some of the stronger April thunderstorm clusters.

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In terms of the percentage of average rainfall, a majority, but not all, of the western district finished on the dry side (again), with a few surplus spots located to the SE of KC.  The east finished with above average rains except a small corridor from the MS river through northern Randolph County, then jogging into Washington County, IL.

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Global Tropics:

Two tropical cyclones were observed this week, what is likely to be the final southern Hemisphere system, and the next in what will likely be a v

ery active season for the western north Pacific.

Severe Tropical Cyclone Quang (24S/21U):

Quang developed in the typical late season development area of the Southern Indian Ocean, just south of the Indonesian Islands of Java and Bali around 11-12 degrees south. Quang developed explosively from a tropical low to a tropical cyclone (equivalent to a tropical storm) in one day, then further to an Australian Category 4 severe tropical cyclone on April 30 with wind speeds of 115 knots or 132 mph, which would also be a category 4 (hurricane) on the U.S. scale.  Quang weakened rapidly thereafter due to strong upper level wind shear and progressively colder waters, crossing the Western Australian Coast as a tropical cyclone (tropical storm) before weakening inland May 1.

Here are a series of images showing Quang’s development, peak and demise (click to zoom in to each image):

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From the Australian Bureau of Meteorology, Here’s the system’s track to landfall (times are local in western Australia) :

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The system’s quick demise was due to rapidly approaching winter in the southern Hemisphere (remember it’s their equivalent of our early November) now.  Water temperatures are cooling, the jet stream is shifting north and large, high pressure systems are now crossing Australia, feeding cooler and drier air into the continent.  The monsoon trough, the dividing line between warm moist air flowing from the equatorial regions and cooler drier southeasterly flow is headed north toward the Equator.  Take a look at these two charts (click to make the more readable and remember that “Late Summer” in Australia is “Late Winter” here in the U.S. and “Winter” there is “Summer” here.  In the peak cyclone season,  the equatorial trough moves southward toward and over North Australia.  Converging winds act on tropical lows or disturbances within the trough, and these can spin up into tropical cyclones.  As we move into this time of year and beyond, this trough retreats to and eventually north of the Equator into the North Indian and Northwest Pacific Oceans. Meanwhile polar low pressure systems and anticyclones (high pressure systems) begin to track further north through Australia.  That brings cool winds to southern parts of the country and dry easterly flow in the center and the north, which joins with the southeasterly trade winds blowing across to the Equator and the trough located to its north.  There really is no convergence and much of central and northern (tropical) Australia is in a dry season.

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That’s most likely why Quang will be the southern Hemisphere’s last storm.  Storms can form near the Equator and primarily west of 90E in the Southern Indian Ocean for a few more weeks, but they become increasingly rare, and if they form are weak and short lived.

Tropical Depression 06W:

The sixth tropical cyclone of the NW Pacific season formed Saturday and will likely become TS Noul. Another disturbance further east may also develop this week.

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We’ll have more on these systems on next week’s update.

Fighting some clouds this week, but mostly dry and trending warmer by next weekend

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We’ve had a coolish week with some patchy frost early in the week and scattered rainfall mid to late week, while a severe weather threat which appeared to loom for the west Friday wound up being much further west. Saturday’s severe weather threat in the east just clipped far eastern sections of the eastern forecast district.

As we begin the new week, we’re fighting a lot of clouds left behind this weekend’s weather system, although drier northeast flow aloft is trying to give some pushback to the overcast skies. At the same time, some high clouds are headed east in westerly flow aloft so while eastern areas may go clear for a while, we’re not likely to see 100% clear skies today.  The west may also see some breaks work in from the east this afternoon with some filtered sunshine through the scattered high clouds as well.  Really, that will be the theme this week, periods of mid level or high clouds as a band of very active weather sets up to our south and west –right over the heart of the southern Plains drought zone.  Certainly good news for them but not for the western district, which still needs rain and will finish April with sub-average rains.  This may give an opportunity for dryness to give some recent improvement a slight push back.  The upshot is, as of this writing there is no threat for severe weather through next Friday (at least).

Let’s take a look at the upper air flow this week. Note how the main polar jet continues to retreat northward (heavy light blue arrows) Gone are the deep polar lows and vortexes of mid winter. The closed low which impacted our weather the week before last continues to spin off the northeast coast and will only slowly spin out into the Atlantic this week as another weaker version drops into the Northeast and takes up residence off SE Canada by next weekend.   We’ll be watching a weaker closed low over the Southern Rockies Monday, which will track just south of due east into the Southern Plains Tuesday, the Mid South midweek and then fade away over the southeast by week’s end.  This low will be the weather and rain maker for the drought-stricken southern Rockies and southern Plains, including northeast Texas.  That’s where most of this week’s severe weather chances will reside.  We’ll have to watch this low as a northward shift in the track could impact our weather by adding more clouds or some light rain opportunities.  We’ll be dealing with periods of clouds all week at times due to the blowoff of rain and storm complexes to our distant west and south.  We’re not going to have to deal with any totally overcast days, but as mentioned above 100% clear skies may not be achieved either.  Partly sunny to mostly sunny might be a good way to describe it.  If the low shifts north, we, might then see a few cloudier days.  Aside from this upper low, the jet is pulling north and it means some milder to warmer weather will try to build in.  The ridge of high pressure off the west coast Monday will push inland early next week and into the Southern Plains next weekend. This looks to bring a return to milder temperatures with 70s likely and perhaps some 80s next weekend.

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Rainfall, as mentioned, is not expected this week.  Most of the region expects little to no measurable rain this week.  Lighter totals exist just west and south of the western district, which is why a subtle shift north in the upper low could bring some of these light totals into that area.

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Here’s the latest on the drought as of last week’s update.  Dryness has been held at bay in recent weeks for the west.  Rainfall this week was around 1/2″ in Kansas City (at KCI – the official reporting station), and typical 7-day rains should be around 1.19 – now through the end of June, so we came up short “officially” at the airport again.  With no rain this coming week, dryness may re-expand to reclaim recently lost ground locally, but may really be dealt a blow in the worse off areas further west across Kansas and south into Oklahoma.  That’s good news for our summer rain setup- even if it’s bad news locally in the short term.

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Week in Review:

It was a cool week relative to averages. The core of the cool weather extended from central Canada south through the Great Lakes and into the Northeast.  Most of the immediate California coast, southern Rockies, Southwest, Plains Midwest, Ohio Valley, Tennessee valley and Mid Atlantic were cool.  The Gulf Coast, Florida, the Inter-mountain West and Pacific Northwest were warmer than average.

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The chill brought threats of frost and frost Advisories to the eastern district where lows in the 30s were expected.

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Here’s a look at this past week’s rain.  Less than impressive in the west, but eastern areas especially the STL metro and S IL had decent totals.  SE Missouri had totals less than 1″.  (Click to make each map more readable.)

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Severe weather was limited, with a threat on Saturday for the eastern district.  The entire area was placed under a Tornado Watch at mid day, but the only severe cluster wound up being a series of storms which formed and tracked through south central Illinois.  these storms clipped Jackson and Perry Counties in Illinois.

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Severe thunderstorm warnings were issued due to wind and hail threats for Jackson County, but the strongest cluster went on through Williamson and Saline County of Southern Illinois and eventually crossed into western Kentucky where the nearest tornado warning was issued.   This radar image from 4:16 PM shows the severe storm over Saline County IL and then storm NW of Murphysboro IL in Jackson County which would go on to prompt a warning for wind and hail as it tracked through De Soto, and on down toward IL Route 13 and on into Williamson County.  The pink and purple tones show areas of likely large hail.

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The watch was cancelled for the entire region several hours ahead of schedule. Despite clearing, westerly low level winds and drier air quickly shut down severe potential. That was good news as upper level parameters were looking good for severe weather earlier in the day.

Global Tropics:

There were no tropical cyclones in either hemisphere and really no candidates for development at least the next several days.  We’re just over two weeks from the beginning of the Eastern Pacific hurricane season and the NW Pacific season could begin ramping up at any time as well.

It should be a quiet week, so we’ll update the drought map on Thursday on FB and our next blog update will be next weekend when we look at May and see what patterns look to prevail as we head into the last week of meteorological spring.  Should any severe weather risks appear, we’ll also place a FB post with the risk area, but right now, there don’t appear to be any severe threats for us.

Wet system provides relief from developing drought; Heavy snows along the I-80 corridor

Much needed rainfall is expected over the forecast districts this weekend. We’ve a wet system moving out of the Southwestern U.S. into the Plains which has the potential to produce anywhere from 1/2″ to 1 1/2″ of rainfall over the region.  Check out this total weekend rainfall forecast:

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The heaviest totals fall from eastern KS through NW/N MO into north central IL. (Some of this as snow). Areas here may see totals near or slightly above 1″.  Keep in mind average January precipitation is an inch or less in many of these areas.  Totals are lower, but still quite respectable over the eastern district with amounts from roughly a little less than 3/4″ to around 3/4″.

As of this morning, the system is still organizing with a good slug of rain falling from northern MO through KS/OK.  Temperatures are just above freezing and will rise slowly during the day.

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That’s snow over SE NE and N KS.. and there will be a significant winter storm for the I-80 corridor and just south from Omaha to well off east of Chicago/Indianapolis and yet another heavy snow for the NYC/Boston areas early next week.  Here’s the weekend snowfall forecast:

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If you have a road trip or airline flight scheduled to any of these areas, check travel conditions and adjust your plans accordingly.  This was once expected to track a little further south with potentially accumulating snows for parts of the district, but the storm has shifted further north and the temperatures within 2000 feet of the ground will be just too warm.  In fact, NWS Kansas City reported this morning that snow was melting just 1000 feet above the ground — or roughly twice the height of some radio towers – that’s the only difference between a cold rain and what would have been a winter storm.. for some the first winter storm of the season.

This rain arrives just in time.  January has been lacking in terms of rainfall with totals ending January 30th well below average in most areas.  This map shows the percentage of average precipitation received as of January 30th (before today’s rain).  The western district has seen totals only 10-50% of average.  For the east, it has been a little better with totals 50-90% of average.  The far SE, roughly along and SE of an Ironton MO-Pinckneyville IL have actually seen a surplus. Keep in mind “average” January precipitation ranges from less than 1″ in Topeka KS to just over 2″ in STL. That means 10-50% of average means some areas out west have had just over a tenth of an inch of moisture all month long.

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Let’s take a look at a series of maps showing the January precipitation totals for our area as of Friday morning. Click on each image to make them more readable and check out the color scale to see the observed totals.  Anything in grey is less than 1/10th of an inch, and anything in greens or blues is less than 1″.

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It’s easy to see the lack of rain for the west and how the far southeast corner of the eastern district was clipped by a band of significant rains early in the month and that corresponds to the map above.

For comparison, here’s the average January precipitation for the region.  2″ for the eastern district and around 1/2″ to 1″ for the west.

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It’s not all that surprising that this week’s edition the U.S. Drought Monitor has placed the western district in an area of developing drought. Drought has been parked over KS for several years now and has not ever really been that far away.  Drought is also established in the Ohio Valley area and has been creeping northwestward toward the southern reaches of the eastern district as well.

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This weekend’s rains have the potential to erase the January rainfall deficits over the region just in time.

We’ll have our weekly outlook post up this weekend and we’ll take a look at weather trends for the coming week.  January 2015 goes into the record books tonight and we’ll also have a look at where January finished in terms of temps/rain and snow.  January’s close also means 2/3rds of Meteorological winter will be over, and that’s a good time to take stock of the many winter forecasts issued last fall (hint: the prognosis is very poor for several).  We’ll also take a look at weather trends into February to see if Winter will be able to stage a rally or if it will finish the season AWOL.

Arctic Chill on the way for midweek – but not unusual for this time of year

Arctic chill is on the way for much of the country– but for the central U.S. this is a “typical” mid winter Arctic surge and not all that uncommon. It will feel a lot colder, especially after a mild December to date.  New Year’s Eve still looks quiet but seasonably cold and there are still big questions regarding what happens this weekend (if anything) with the storm system which will bring winter weather to the Southwest U.S. this week.

All-in-all it is a rather typical late December day across the region.  As shown below, temperatures are in the upper 30s to low 40s over the district – which is actually a degree or two above average.  Remember that average highs in the closing couple of days in December are in the upper 30s.

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The cold blue and purple colors over the Central/Northern Plains west to Montana and east to Minnesota show the Arctic air. Subzero weather continues in parts of ND/MN.  Colder weather has actually spread southward to the Desert SW with Phoenix/Tucson in the mid 50s..where averages for this time of year should see temperatures in the upper 60s.  It’s easy to see in the map, that the main push of the cold has been down the Front Range of the Rockies where there is less of a push eastward.

This cold air will bring snows to unusual locations.  The map below shows 3-day snow forecasts for the Southwest.  Snows will be visible on the mountains just E-N of Los Angeles, and from coastal locations, snow will be visible on the peaks south to San Diego and the Mexican border. Las Vegas NV is actually expecting a dusting to 1/2″ of snowfall and in an odd twist, there is a greater potential for accumulating snows in Las Vegas NV than there is in Chicago IL in the next 7 days.

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Because of this, Winter Storm Watches cover a decent-sized chunk of land over AZ/CA/NV.

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For us, the coldest morning of the week will be on December 31, Wednesday morning.  Lows will range from the single digits out in the western district to low or mid teens for SEMO/SW IL and STL.  Average lows for 12/31 range from 18-20 so temperatures will be 4-6 degrees colder than average for STL/SEMO/SW IL to as much as 10-15 degrees colder than average for the KC area.  The strongest and deepest push of cold air is west of the district, with a cold core of -20 to -30F temperatures over western NE/WY/CO.  If we had snow on the ground around here we could have been significantly below zero in KC and around zero in STL/SEMO/SW IL.

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What’s powering the chill is a very strong high pressure area, forecast to peak early Tuesday morning at a central pressure of 1062 MB, or 31.36″ on your home barometer.  The center of the high will build down from Montana into far W NE/E CO and rapidly collapse later in the week over the southern Plains.  Pressures here won’t get that high.. they’ll peak at around 1038 MB in SEMO/SW IL to around 1042 MB in KC.  That’s still a lot higher than we’re at right now so if you notice aches and pains tomorrow, it might well be the increase in atmospheric pressure.

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25 years ago..another strong Arctic high took more of a direct aim on our area. That brought record cold to the region with temperatures around -20F locally in late December, 1989.  The difference then was there was a lot of snowcover down over the Midwest/Plains and that high moved from Canada to the central U.S. and not south down along the Rockies.

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This high gives us more of a glancing blow to the west and there is plenty of snow-free ground around here.  After the cold wave peaks New Year’s Eve Morning, it quickly collapses.  These two charts show temperature difference from average 12/31 at 6AM and then Friday 01/02 at Midnight.  The lighter blue to white tones on the right image show temperatures just a few degrees below to near average.  The darker purple and green tones have retreated westwards and become more scattered. (Click to make the images more readable).

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Some sort of system is expected to result from the winter storm in the Southwestern U.S. this week.  Unfortunately, as was indicated yesterday, there has been almost no confidence in any one outcome for this system.  The situation remains that way today. Solutions for our western district vary from a significant winter storm to an icy mix to light snows or even nothing at all.  Solutions for eastern areas of our district range from snow potential to a wintry mix to rain. Computer model guidance continues to flip back and forth from one computer model run to the next and from one computer model to another. There is still no real point in spending a lot of time on this system right now, and it’s just something to keep in mind as we move deeper into the week.

Southern (Winter) Solstice at 5:03 PM CST Today

Winter begins at 5:03 PM Central Time today

Today marks the Southern Solstice or the Winter Solstice in the northern Hemisphere.  The sun reaches it’s southernmost track on it’s annual journey.  For those of us 35-40 degrees north longitude,  as we are here in the district, it means a late sunrise in the southeast, a low tracking sun not far above the horizon through mid day and an early sunset in the southwest. Despite winter’s arrival, truly cold weather still appears a little ways out.

The relative locations of the sunrise, path and height of the sun above the horizon and sunset at the solstices and equinoxes.

The relative locations of the sunrise, path and height of the sun above the horizon and sunset at the solstices and equinoxes.

Daylight is at it’s minimum today, with just over 9 hours and 25 minutes from sunrise to sunset.  The sun is also dimmer/redder than it is during mid summer as the light has more atmosphere to travel through.  Recall the hot, harsh, and bright white mid day sun 6 months ago in June.

The angle of the sun through the year changes the intensity and color of the light reaching the surface,

The angle of the sun through the year changes the intensity and color of the light reaching the surface,

The good news is that sunsets have already begun to get later, and as of tomorrow, we gain more minutes in the evening than we lose in the morning for a net gain of daylight. By mid January, we begin to gain daylight in the mornings and the pace of the lengthening days will really increase.

Compare our daylight/sunrise/sunset with other cities across the country today (image: Washington Post).  Fairbanks Alaska  has just under 4 hours of daylight, Seattle and Minneapolis 8 1/2.  Southern cities such as LA, Atlanta and Phoenix hover closer to 10hrs, while Miami remains at nearly 10 1/2 hours.

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Let’s take a look at temperatures across the northern hemisphere as winter begins:

Bitter cold continues in eastern Asia including Siberia where temperatures average near 60 degrees below zero.  Readings in western and central Asia are a bit less cold.

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Across the Arctic where there is no daylight today, subzero readings stretch across the pole to Greenland, the Canadian Arctic and north Alaska.

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Europe is relatively mild with no areas below zero, save the high terrain of northern Sweden and Norway.

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Here in North America, temperatures are also not bad with very limited areas below zero and no area of the lower 48 below zero.

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In the Southern Hemisphere this is the first day of Summer, with temperatures hot over Australia. Antarctica, where there is 24 hour daylight, readings are very cold but not as cold as they are now in Siberia.

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December, to date has been quite mild over the lower 48, as this chart shows, with chill limited to a few areas in New England, the outer banks of VA/NC and Florida.  The warmth has been concentrated over the central Rockies and Great Basin.   Across the district, temperatures have been 2 to nearly 5F above average.  Carbondale the “least” warmest with 2.1F above, and Topeka the warmest with +4.9F.

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Pacific flow has been dominating North America this month. This moist flow has been cloudy for many areas and that brings up an interesting fact. What’s interesting is that, with the clouds, daytime temperatures have been nearly average with a FEW days above, while nighttime lows have really made the difference being above to well above. In fact for the STL region, only two days in December had lows below average.  Two days also had lows warmer than the average high. St. Louis has had 0 clear days, 6 partly cloudy days and 14 cloudy days.  Kansas City has had 1 clear day, 4 partly cloudy days and 15 cloudy days. Carbondale has had 0 clear days, 7 partly cloudy and 13 cloudy days.  Topeka, KS has seen the best weather with 5 clear days, 1 partly cloudy days and 14 cloudy days.  Although it has been a warm month, the source of the warmth lies more in mild overnight lows rather than a string of very warm days.

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December has also been mild in Europe, western and central Asia and the Middle East.  China, south central, eastern Asia and Siberia have suffered in the cold.

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We’ve a bit of rain coming this week with amounts rather modest,  and highest in the east and south.  This warm system rolls into the area beginning tonight in KC and winding up Monday night there, while arriving Monday for SEMO/SWIL/STL and winding up Christmas Eve with perhaps a few snowflakes as the seasonably colder air wraps back into the system as it lifts out. Barring the GFS, no significant accumulations are expected in eastern areas of the district.  The longer duration of the weather system in our east is due to a secondary low which forms along the Gulf Coast and tracks north-northeast.  This low becomes the main center of the storm system when it lifts into SE Canada by week’s end. It is this secondary low which the GFS (alone) uses to create accumulating snows for SEMO/SW IL/STL. Kansas City/Topeka are far enough removed to miss any effects of this secondary low and instead get a band of light precipitation with the original low’s cool front and that’s it.

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If you’re holding out for a White Christmas, you’re best (and only fading) shot is in STL/SEMO/SW IL and with the lower-resolution GFS model.  That model has insisted that a small band of heavy snow develops over the eastern district as a secondary low tracks through KY.  The GFS has insisted on this for 24 hours now.

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All the other higher-resolution models (including the GFSx which replaces the GFS next month), have nothing of the kind showing up.  Here are all the charts for the same time period, noon Christmas Eve:

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We’ll have to see how this plays out with today’s suite of incoming data.  (Note: the just in morning run of the GFS has backed off on this a little, but still has accumulating snows in the same area Christmas Eve and no other model is producing significant wintry weather).

Christmas itself looks dry and mild at this point with highs in the middle 40s (GFS model run not withstanding).

After Christmas it’s back to cooler weather although not really cold.  We’ve got three things keeping us from getting truly cold.  The first is that the Pacific flow has kept the Arctic chill from becoming established in our cold air source region in the Canadian Prairies.  Mild Pacific flow becomes downslope off the Canadian Rockies and warms further.  The Arctic flow is circling the pole well north.   There are signs that could begin to change later this week.

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That leads to our second issue. Because of that Pacific and downslope flow, temperatures there are only a little colder there than they are here. Readings are in the teens and 20s, while chilly, that’s mild by late December Canadian standards. We need the Canadian Prairies to really get subzero cold before we can start to think about any Arctic air headed in our direction.

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The third issue: When cold air moves south, it starts to be modified by the ground it travels over, especially if there is no snowfall. The map below shows plenty of snow in Canada, but not so much south of the border.  Except for the mountains, and one spot in North Dakota, you’ll have to go all the way to south central Alberta, Saskatchewan or Manitoba to find snowcover deeper than 6″. We really need snowcover to expand further south and east – and deepen – before any Arctic air developing in Canada has a chance of retaining it’s chill as it head south.

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This gives plenty of time for the “cold” air to warm as it moves from the Canadian border to the district.  The bottom line is that we’ll likely see a return to near to slightly below average temperatures in the weekend which follows Christmas.

When will it get really cold?  There are signs of a change in the upper air pattern to our north which would allow substantial cold to begin to build in Canada.  There are also forecast to be significant snows to our distant north and northwest this week and this weekend, which would increase the depth and southward extent of the snowpack.  The earliest time these factors would come together to impact us would be in the days before the new year.  That’s still 10 days away though and a lot could change timing wise between now and then.  As we’ve been mentioning – these transitional patterns where large scale and longer term changes take place make it a tough to have confidence in the specifics just yet.

Lots of clouds, chance for rain but quiet this weekend/Travel issues for PACNW, Rockies

There won’t be a whole lot going on weatherwise this weekend, which is good news for those planning travel.  We’ll have lots of clouds and a chance for some light rain here locally. White Christmas chances look low.

Outlook…

Weekend…lots of clouds although a few thin spots can’t be ruled out.  Best chance at seeing sun will be in the east on Sunday.  We’ll have slightly above average temperatures with highs back to the 40s.  Light rain could return to KC late Sunday night.

Christmas Week…A bit of light rain to start Monday off with.. lingering into Tuesday east.  Temperatures continue to be mild with highs in the 40s Mon/Tues.

Christmas Eve…Turning cooler..but still near average for late December.  Highs in the 30s.

Christmas Day…Seasonable. Dry. Highs in the upper 30s to around 40.

After Christmas…watching the evolution of a possible Plains low pressure area…  Track right now is north of us which means rain chances and mild before turning much colder New Year’s Week.

Clouds…

Not much new to say here.. mid afternoon visible satellite shows the area socked in with low cloud cover.  We’ve been in this grey pattern for several weeks now.

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Travel issues:

If you plan on heading out across the country today, here are the satellite images.  A lot of cloud cover over the eastern U.S. and another storm approaching the PACNW. Florida, SOCAL and AZ seeing quite a bit of sun.

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About the only weather hazards are in WA/OR where a very wet weekend is set to begin as a strong Pacific jet rams into the Cascades with heavy rains, coastal high wind (brown) and possible flooding (green).  Further inland and up in elevation, heavy snows are expected in ID/MT/UT/CO/WY where winter storm watches (blue). Winter weather advisories for lighter snow cover NE NV and the Sierra Nevada (purple). Check with your airline if you’re headed into these areas.

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Our late weekend system is not expected to produce much in the way of rain with very light amounts expected between now and Monday evening.  Snow will also be very light and mainly restricted to IA/WI/NW IL.  Those heavier snows show up in CO/WY.

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Finally, we’ll take a look at the forecast maps for Christmas Morning.  They’ve not changed a whole lot and still argue for dry weather around here.  We’ll still have to watch timing of the low in the Great Lakes as any slowdown could mean weather impacts here on Christmas.

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The weather system shown in the Rockies is the one which may have impacts for us in one way or another the weekend after Christmas into New Year’s week. Have a good weekend and we’ll update the blog on Sunday evening.