Some stronger storms possible west tonight, overall a near average week. The western district is becoming very short on rain..

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Springtime means more active weather, and we’ve certainly had that over the past week.  Heavy rains have continued to plague the eastern district, severe thunderstorms dumped large hail and there were several radar indicated tornadoes, but none fortunately which were confirmed as touching down.  In the west, storms developed just east of the district with one severe thunderstorm producing 2″ hail in north Kansas City, but widespread rains missed most areas and drought is a mounting concern.  This week, active weather continues although widespread severe weather does not seem as likely as it was last week. Rain chances will finish the weekend, return mid week and then possibly next weekend or early the following week.  We don’t have any expectation of any frosts, freezes or extreme heat, but there are some indications we may face another frosty morning or two just beyond this outlook period.  We’ll start this week’s focus with the western district, where rain (or the lack of) is beginning to make the news.  There was some welcome rain (Sunday Morning) and the opportunity for more rain (overnight Sunday), and there is the chance for a few strong or marginally severe storms overnight.

Western District: Marginal Risk for Severe Weather Sunday night or Monday Morning:

The Storm Prediction Center indicates there is a “Marginal” risk for severe weather in the western district this evening and overnight.  Marginal means isolated severe storms with low risk for any tornado activity, winds of 40-60 mph in the strongest storms (58 mph is considered a “severe” thunderstorm wind gust) and hail up to 1″ (quarter) size.

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This activity is expected along an incoming cold front. Here’s the high resolution computer forecast of the radar at 2 AM Monday morning with this first wave of showers and thunderstorms, blowing through in about 2 hours and leaving anywhere from 1/3″ to 3/4″ an inch of rainfall.

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The NAM-4 model is onboard with this as well, but about an hour later (3AM) into KC.  It too also leaves 1/4″ to 3/4″ of rain.  Both models weaken this line by the time it reaches the eastern district early (around the morning commute).

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Western District: Drought Update:

With the continued misses in rainfall, dryness continues to advance into the west. A light to moderate dose of rainfall fell early Sunday morning, with 0.40″ at Kansas City International and 0.36″ in downtown KC.  In this estimate any of the grey tones are less than 1/2″ while the purples are 1/2″ to 1″. Blue tones are 1-1.5″ totals and greens are 1.5 to 2″ totals.  This rain helped, but even so, the area is teetering into drought.

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Abnormally dry conditions now dominate over the southwest half of the district, and those conditions deteriorate into moderate drought southwest of Emporia KS and severe drought over and west of Wichita, KS.  As of this writing, Kansas City is:

-0.07″ for April,

-1.91 for 2015,

-20.17″ for the 2010s decade,

-24.66″ for the 2000s.

Average annual rain is 38.86″ so they are just under 14″ short of missing the equivalent of an ENTIRE YEAR’S worth of rain since 2000.  Those are some pretty impressive numbers in a bad way.  It’s one of those scenarios where those who need the rain continue to miss it (the west) and those who don’t need any more continue to get it (the east). By contrast, St. Louis is within an inch of the average rains which would typically fall between January 1, 2000 and April 12, 2015.

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The U.S. Drought Monitor, which produces these maps only includes rains which fall between 7AM Tuesday and 7AM the following Tuesday.  Rain falling this weekend, including another chance Sunday night/Monday morning will be included in next weeks map.  We’ll see if these rains can be enough to prevent further deterioration. Thunderstorm rains are spotty as we’ve seen and we’re moving out of the time of year when widespread heavy rains are common and into the time of year when individual storms or storm clusters can flood some areas and leave others rainless.

Model rainfall forecasts have not been all that helpful.  Part of the reason, as discussed above, is the spotty nature of warm season rains. The NWS GFS Model has been gyrating wildly between wet and dry solutions for the western district. Yesterday it expected around 1″ over the next 10 days, overnight, it flipped to almost 5″ of rain for the same period and this morning reverted back to 1/2-1″ of rain for the next 10 days (most of that falling Sunday night/Monday morning). The European model is averaging anywhere between 1-3″ of rain over the next 10 days. The Canadian model prints out less than 1/3″ over areas on the NW edge of the western district to 1″ in KC and 3″+ on the far SE side over the next 10 days. The UK model gives KC less than 1″ in the next week and finally the FIM9 model shows around 1.3″ for the western district in the next 10 days.  The NWS WPC officially prints out widespread 1-1.25″ totals in the west over the next seven days. Climatology says KC should average around 1.1″ of rain every 10 days in March.

The Climate Prediction Center (CPC) maintains more or less equal probabilities for above/below precipitation for the majority of the remainder of the month for the western district, but does bring enhanced probabilities for dryness closer to northern sections of the western district April 20-26.

 2015-04-12-1452-610prcp_new2015-04-12-1452-814prcp_new

The NWS Climate Forecast System V2 is still hopeful for a turn around in May with 100-125% of average rain for the west.  May and June are the wettest months in the west on average with 5.23″ of rain each of those months. That would mean anywhere from 5.23′” to 6.53″ of rain would fall in May for this to verify and the model has been a bit optimistic in rainfall projections for quite a while now.

 

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The Week Ahead:

Taking a look at the model jet stream forecasts this week we can see that the main polar jet (heavy blue arrows) has now moved north into Canada and the main polar low is parked up near Greenland. Several weaker mid/high  latitude lows are noted in the Gulf of Alaska and over Canada.  Another jet is further south in the U.S. and this is the main driver of our weather. A very weak upper level low in the SW High Plains Monday is absorbed into the flow by Tuesday as a sharp dip in the jet over Washington State becomes a trough and low over the Rockies.  This low eventually becomes cut-off from the main belt of westerly winds and meanders over the southern Rockies late week before beginning to re-attach to the westerly flow late week as a low and trough passing through Ontario/Manitoba begin to pick up the now much weaker low. This low moving into the Rockies on the Wednesday chart will be in part, responsible for mid week rain chances.  Rain chances next weekend will depend upon how the low over Canada does (or does not) sync up with the slowly spinning down low over the southern Rockies late next week. If the low does not reconnect, it may well spin down to oblivion where it sits and never be much of a player in next weekend’s weather.  If the two lows sync up as shown on the map for Sunday 4/19, it might not only provide for shower and thunderstorm chances but also a burst of cold air (note the ridge over western Canada –and remember how that was such a player in our late winter cold snaps). Now mid April cold is not anywhere near February or March cold, but that would be a scenario where we might need to think about a frosty morning or two..IF things sync up that way.  It should be noted though that the European model also syncs the two features up a day or two later than shown here,  but the European model can tend to be a little slow with southern stream lows so there is some concern we may be dealing with at least one more chance for some frosty mornings this time next week.

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There will be the possibility for some severe weather this week with the midweek system, but the differences in computer model solutions make highlighting any particular area over any other difficult at best, unlike last week when we had a very good idea days in advance which areas would be at greater risk.  This time of year always be prepared for the possibility of severe weather and we’ll post FB updates should any part of the district be placed in a risk area.

Rainfall for the next 7 days starting today is expected to be most significant in the west, with 1/2-1″ totals there while eastern areas seen generally 1/4-1/2″ totals.  It should be noted that a good part of that western total arrives tonight/Monday AM, so a miss might bring all areas down to the 1/4-1/2″ total for the week ahead. These are generalized totals and the actual week’s total will likely vary much more from place to place, depending upon where storms track.

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Week in review:

It was a very active week across the district with severe weather and heavy rains. Temperatures were warmer than average overall, and that included most of the U.S. south of 45N latitude and east of about 115W longitude.  The west coast was cool as was the northern tier and New England.

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Western District: Missed heavy rains again:

Again, the western district missed most of the action with spotty light showers and one strong thunderstorm. Rain did fall on Sunday morning, however as discussed above. Well off to the south there was a supercell thunderstorm northwest of Joplin in SW Missouri. This is a classic example of a “hook” echo storm.  Notice the blues and reds close in the left panel image,  showing the rotation. The “hook” is due to an inflow notch where incoming air rotates into the storm.

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This is not the same storm, but it does show a 3-D representation of the “hook” part of the storm.

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One lone strong and hail producing storm impacted N and W portions of the KC Metro Wednesday evening. The pink shading in the storm represents the high reflectivity of the hail in this storm.

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For most of the west though, the cap, which we discussed last week was just too strong to allow widespread severe weather in the west.  Here’s that simplified graphic we used last week to show how the cap works.  There were also storms in SE KS/SW MO earlier in the day and southerly winds blew this rain-cooled air into the KC region which only helped to strengthen the intensity of the cap.

CROSS SECTION-CAP

Here is an image of the capping inversion represented by the orange and red tones in temperatures aloft.

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The net result was little to no significant rains again for the west as storms formed just E/NE of the district and moved away to the NE or formed well SW of the district and bypassed the area to the southeast. Extreme SE portions of the west including Cass/Johnson County MO fared much better with rainfall.

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The East: Rains and Severe weather more widespread

The cap was not nearly as much of an issue with it being much weaker and able to be broken in the east much easier.

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The eastern district continued to get pounded by heavy rains and multiple rounds of strong to severe storms. Here’s the storm which would prompt warnings for the SE Missouri Ozarks.  Notice the right image showing the hail cores along the Franklin/Crawford-Washington County lines.  This was at 2:31 PM. This storm originated east of Kansas City that morning.

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A storm which produced 2-3″ diameter hail near Potosi MO also developed into a storm with strong rotation and tornado warnings for St. Francois and Ste. Genevieve counties.  There were no reports of a tornado touchdown. Again, note the bright blues and reds close together just north of Farmington. That shows rotation aloft (the beam is in the cloud level at this distance from the St. Louis Radar which is in Weldon Spring, MO.  This image was taken at 4:26 PM.

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This storm cluster was the only major system in the district at that time and had prompted a tornado watch.

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By 5:45 PM. The warning was extended into Perry County MO, but the rotation had begun to weaken, although there was a lot of hail aloft (pinks and purples).

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45 minutes later, the rotation was gone and the tornado warnings were replaced for severe thunderstorm warnings for hail and high straight line winds.

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The cold front, moving in on Thursday, brought more of a broken line of thunderstorms to the area, although tornado watches were issued for the entire area.

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Severe thunderstorms with large hail, winds and lightning impacted SW Perry county MO just before 8 PM.

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Another tornado warning was issued for part of Perry County MO around 9 PM for radar indicated rotation moving out of Cape Girardeau County, again there were no reports of any tornado touchdowns.

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3-D images show the rotation aloft.

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These several days of storms produced widespread heavy rains across the district with 2-4″ totals common.

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Global Tropics:

Tropical Cyclones Ikola, Joalane and Solo were all systems active south of the equator.  Ikola and Joalane in the South Indian Ocean were discussed in last week’s post and were just forming at that point.  Ikola developed just west of 90E and was named by the TCWC on Reunion Island.  In the southern hemisphere, all storms of tropical storm intensity (named storms) are called “tropical cyclones”. Some warning centers designate hurricane intensity storms as “severe tropical cyclones”.  Here in the northern hemisphere, tropical depressions, tropical storms and hurricanes/typhoons are all considered “tropical cyclones”. They are not usually named until they reach tropical storm intensity.  The U.S. issues advisories on all tropical depressions from the Dateline in the Pacific to the African coast in the Atlantic. (The U.S. Navy’s Joint Typhoon Warning Center does the same for systems west of the dateline). The warning center in Tokyo, Japan which covers the Pacific west of the dateline issues advisories on tropical depressions expected to become tropical storms within 12 hours and on tropical storms, severe tropical storms and typhoons. The North Indian Ocean has a different system naming systems of tropical storm-strength or greater, which they term “cyclonic storms”. Storms in the north Indian Ocean are far fewer and usually occur in May/June or October/November.

Ikola (21S/14R/19U) had a brief life as a hurricane intensity system as it moved rapidly southeast to the west of Australia. It quickly developed an eye, but was dissipated by colder waters and strong wind shear.

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Joalane (22S/13R)became a hurricane-intensity system east of Reunion Island- (which is the island visible to the left of the storm) and tracked due south towards strong winds aloft and cold seas, becoming a mid latitude storm system in the far southern Indian Ocean Sunday morning.

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Solo (23P/15F) developed quickly near the Solomon Islands in the South Pacific along 160E and had a very short life as it tracked southeast well off the coast of Australia.  Solo developed near where the very destructive TC Pam formed earlier in the season.

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We’re now nearing the end of the southern Hemisphere season, which ends for most areas by the end of this month.  Remember, they are moving into mid Autumn south of the equator as we move into mid Spring.  Things will likely be quiet in the tropics before the northern hemisphere season begins to pick up.  The NW Pacific will become active first, then the NE Pacific and finally the Atlantic.  The preliminary outlook from hurricane forecasters indicates a quiet year for hurricanes for the Atlantic. That being said, it only takes one hurricane to do a lot of damage so if you plan a trip to the Gulf/Atlantic coasts, the Caribbean, the southern Baja Peninsula, the southern Pacific coast of Mexico or Hawaii be weather aware for any possible tropical cyclones.

Here are the first few names for the Atlantic this year: Ana, Bill, Claudette and Danny.

In the Eastern Pacific (out to 140W): Andres, Blanca, Carlos and Delores.

In the Central Pacific (140W to the Dateline): Ela, Halola, Iune, Kilo

In the Western Pacific (180E to Asia): Noul, Dolphin, Kujira, Chan-hom

In the North Indian Ocean: Ashobaa, Komen, Chapala, Megh.

Storms crossing from one ocean to another which remain a tropical cyclone keep their original name.

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