It will be another mostly quiet week for the western district with only a dwindling chance for rain while the eastern district sees a few rain chances, but nothing like this past week. Our unseasonably warm conditions will ease back toward seasonal levels for mid March (highs in the mid 50s/lows in the 30s), after all it is still astronomical winter until 5:45 PM this Friday. Drought and fire weather concerns are the main threats in the west as we begin the week.
Today and Monday’s biggest concerns will be warm dry air and fire weather threats for the western district and westward into the Plains. Red Flag (Fire Weather) Warnings are up for a large area from W IA and NW MO through large parts of KS/NE and OK. The combination of warm temperatures, very low afternoon humidity, long term drought, lack of rainfall, the season (dormant or dead vegetation) and gusty winds will create extremely critical fire weather conditions. That means any fire could quickly grow out of control.
Highs today and Monday will warm to the 70s and even some 80s.
Looking ahead, the jet stream, up near the US/CN border drops back south this week as a large polar low drops south to Hudson’s Bay. We also see the NW CN/AK upper ridge try to begin to get its act together once again. At lower latitudes, the subtropical high weakens and retreats southward into the Caribbean and tropical east Pacific. This pattern will bring renewed cold to New England (and possibly more snow) and more seasonable temperatures for us. There are some indications present that we may see at least one more resurgence of our Feb/early March pattern later this month..meaning a return to below average temperatures toward the end of the month. Too early to do garden work just yet.
Let’s track the air masses this next week. The warmth subsides, shifts south and then returns late week before fading again next Sunday. The midweek blob of blue is where the model sees clouds and rain.
In terms of rain, most stays south of the western district, with better chances east. The Canadian model is alone in bringing widespread wetting rains to the west. The eastern district is more prone to being in the line of fire for more rain if these systems track further north than indicated today.
Week in Review:
Heavy rain was the big story over the eastern district as a moist gulf storm system passed by to the south. Take a look at this view of the radar midweek showing heavy rains from OK to the Ohio Valley. This system remained in place into Friday and Saturday when the rains eventually faded away.
Here’s a look at the gridded rainfall forecast issued as the event began. 2-3″ of rain were predicted for SEMO/SW IL with a sharp cutoff to the northwest.
Here’s the radar estimated total rains. Not too bad in comparison. The orange totals are around 3″ with the yellow orange 1-2″ and greens less than 1″.
When the system was done, the contrast in the percent of average rain to mid month was stark. The western district has received 0 to 5% or little or no moisture all month. Kansas City has had no measurable rain this month. Th eastern district has seen precipitation from 90% (parts of STL) to 200% of average (SEMO/SW IL) thanks to the snows and now the rain.
The multi-year dryness/drought which has never really retreated out of the Plains since 2012 is on the move again and is expanding north to include the western district. Oklahoma and Texas continue to be the core area of drought east of the Rockies and an area of drought over the Northern Plains is heading south to join with the Southern Plains drought region. If things don’t change soon, we’ll have an unbroken corridor of dryness and drought from the Canadian to Mexican borders. Not good situation to be in for the Plains as planting season rapidly approaches and this can have implications into our summertime pattern (excessive heat and worsening drought feeding back). See the post a few weeks ago for more information on that.
After several weeks talking about record cold, it was a nice change to have Springlike temperatures in place last week. Highs in the 70s were common in the western district with clouds and rain limiting temperatures east. Here are late afternoon readings Wednesday and Thursday. Warmth was greatest where sunshine, warm air aloft and warm downslope winds concentrated over W KS/NE and SD.
Severe weather has been very quiet as well. Here’s the Storm Prediction center tornado count for 2015 as of March 14. We’re running well below average for this early point in the year. This has been due in part to sustained cold into early March and then a lack of a strong north to south temperature gradient and unfavorable upper level flow more recently.
2014, 2013 and 2012 were all below average years for tornadoes in the U.S. The last above average year was in 2011. In mid March, typically the sever weather threat remains from the Red River Valley to the Southeast with a small increase northward into our area.
In the southern hemisphere, where it is the equivalent of mid September for us, the warm ocean waters have fueled a handful of tropical cyclones (the southern hemisphere equivalent of tropical storms, hurricanes and typhoons). TC Haliba developed east of Madagascar in the southwest Indian Ocean and tracked southeast over open water. TC Olwyn formed over the Southern Indian Ocean south of Indonesia and NW of Western Australia and it tracked southward, making landfall and running inland east of Perth. TC Nathan took shape in the Coral Sea northeast of Queensland and looped around just off the coast. A rare subtropical storm Cari, formed off the coast of Brazil the southern Atlantic before becoming a gale low in the far south Atlantic Ocean. The big news was with TC Pam, which formed east of Papua New Guinea and strengthened into a Category 5 (on the Australian/South Pacific scale) tropical cyclone. It devastated the island of Vanuatu with the eye tracking right overhead. The Northwest Pacific also has an early season tropical storm which passed near Guam. The map below shows the formation and track of each of these tropical systems. Most formed over the very warm waters (reds, oranges browns) near and south of the equator. Tropical cyclones usually need water temperatures of 26C (yellow) on this map to develop and continue. ST Cari, off of Brazil, formed right on the edge of this threshold.
This chart is the same, but shows the sea surface temperature anomaly, or difference from average. You’ll notice that all of these systems formed over or near patches of warmer than average waters, especially of note is the patch off Southern Brazil, no doubt helping this rare system to form.
Here are some images of several of these tropical cyclones at or near peak intensity. (Click to make them more readable). You’ll note how Pam has a small and well defined eye, one of the hallmarks of an intense tropical cyclone and that the eye is tracking very near or over the small island groups.
We’ll have an updated post out next weekend.