Thursday Morning Update

Thursday, December 6th 2012, 5:39 am
By: Alan Crone

Wind speeds will be increasing today in advance of the next upper level system moving across the central and northern U.S.  Pressure falls east of the Rockies will allow southerly winds to increase this afternoon from 15 to 20 mph with daytime temps moving into the mid and upper 60s.  A few clouds will be likely at times, and the fire danger will be elevated across the entire state.  The historic drought combined with dry vegetation and strong winds would promote a rapid wild fire growth today.  While many areas remain outside of official burn ban status, it's recommended you refrain from burning today.   

The first boundary will arrive near southern Kansas tonight and could produce a few isolated showers to our northeast.  This boundary will then ooze southward during the day Friday but our temps should still move into the lower 60s for many locations with south winds shifting to the north.  Friday evening into pre-dawn Saturday morning we may see a few isolated thunderstorms across extreme eastern OK or more in Western Arkansas. This boundary will more than likely move northward Saturday afternoon as the stronger upper level trough begins to move across the western U.S. There's also a very remote chance of an isolated shower or storm Saturday night as this boundary slides slightly northward back into southern Kansas before the major arctic air mass blasts through the region early Sunday.  

The main upper level pattern will undergo a significant change during the next 48 to 72 hours allowing a mid-level long wave trough to influence the middle part of the country this weekend.  Model data a few days ago offered more of a "closed low" suggestion at the base of the trough, but are now supporting more of an "open wave" as it slides across the region this weekend.  This means our chances for any winter precipitation with this system will remain very low due to the progressive nature of the flow and moisture being quickly moved east and south.  There still remains a slight chance (20% or less) for some flurries late Sunday evening into early Monday, but I anticipate most of this would remain north across southern or southeastern Kansas, if any at all.  

The big headline for this forecast package continues to be the surge of cold arctic type air that will move southward Sunday into Monday.  These shallow air masses typically arrive faster than model data solutions, and we continue to think this will be the case for the Sunday arrival.  We'll be "inverting" the temps for the Sunday forecast, meaning the early morning readings will be the warmest part of the day( upper 40s near 50) with readings by 6pm falling to near 34.  Strong northwest winds in the range of 20 to 35 mph will create wind chill values by Sunday evening into Monday morning into the teens.  Monday's temps could easily stay in the upper 30s for the afternoon day with mostly sunny conditions by early morning.  

Shallow air masses can be difficult to erode but I don't think this one will stick around too long.  There is very little snow pack across the northern portion of the country.  A snow pack would act to keep the colder air " cold" longer, but with the lack of snow pack, we're anticipating the air mass to modify Wednesday with temps moving into the upper 40s Tuesday and then the lower 50s Wednesday.  Yes, that's still pretty chilly, but this arctic surge will be a passing shot compared to the real deal arctic plunges we usually see in January.  But I do think the pattern will remain favorable for even more of these surges to slide across the country during the next month or so.  We're even seeing signs of another stout front for late next week. Stay tuned!


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Have a super day!

Alan Crone