Updated 845am CT – Monday / 21 April 2014
…. A Low Pressure Disturbance Moving Eastward Later Today into Tonight ….
…. A Mostly Dry and Stable Weather Pattern over the Next Seven Days ….
On this Monday morning…. a surface high pressure area /1021mb/ is over the southeastern USA with a low pressure area over the western upper Mississippi valley /1011mb/ with a cold front extending south southwestward into southern Colorado. As a result of this surface weather pattern, our local surface winds are southeasterly.
In the upper levels of the atmosphere… a strong upper air disturbance is over northern Oklahoma north of the OKC metro area. As a result of this upper air wind pattern, the upper level winds over south central Texas and the Austin metro area about 18,000 feet above the ground are westerly 45 to 55 mph.
With the surface high pressure to our distant east, we’re seeing a pronounced south southeasterly surface wind flow. This flow has allowed a more moist and a slightly more unstable air mass to continue its hold on our local area.
By this afternoon into tonight.. the upper level low pressure disturbance to our north will combine with the atmospheric moisture.. limited instability and daytime heating to result in isolated to widely scattered thunderstorm development. The NWS/Storm Prediction Center has forecast a “slight risk” of severe thunderstorm development.. with the main risks of larger hail and damaging straight line wind.. for areas from Austin and westward and northward for this afternoon through about midnight tonight. This is another of these “low probability” and “moderate to high impact” weather events that we’ve seen this winter and spring. At best, rainfall, at any given location, will average 1/4 inch with some isolated heavier totals.
As the upper air disturbance moves eastward out of our by daybreak tomorrow, the weak cold front.. to our north currently.. will move southeastward into our area as it weakens. We’ll see a brief wind shift to the northeast with the front but the surface winds turn back south southeasterly by tomorrow night into Wednesday.
We’ll return to more sunshine.. with a partly cloudy sky.. for the middle and latter part of the new week.
Another upper level low pressure disturbance.. off the Pacific Ocean and across the southwestern USA and northwestern Mexico.. will approach the area by next weekend with another cold front forecast to approach our area by late Sunday into Sunday night with it moving through the area by daybreak next Monday. At this point, rain chances look limited and mainly Sunday into early Monday.
Regarding my forecast, my local forecast confidence: My forecast confidence is high today through tonight (isolated to widely scattered thunderstorms and any slim severe weather probability being confidence limiting factor) then rising back to high to very high for tomorrow through Friday. My confidence falls back to medium to high confidence for Saturday and Sunday as the next upper level low pressure storm system and surface cold front approaches the area.
Have a good Monday…
Meteorologist Troy Kimmel
Contact me:
tkimmel@austin.utexas.edu
http://www.facebook.com/troykimmel