Tuesday, March 11, 2008

Chase Oppurtunities Thurs-13th/Fri-14th

-Basing both of these forecasts off 12Z NAM/WRF from March 11, 2008-
-Both are likely to change!-

Thursday 13th
Shortwave trough crossing the central/southern plains Thursday afternoon could set off a few storms from Kansas to Texas. Area of interest would likely be in Ardmore, OK / Gainesville, TX area. At the surface, NAM forecasts ample moisture return into the area (50~55Td) with a sfc low developing in west TX ending up near Childress-Abilene-Wichita Falls region by late afternoon. Sfc winds may back to a southeasterly direction in response to deepening sfc low (<1000mb) while 850mb winds are decent at ~25kts from ssw. 500mb flow with associated trough will likely be in 40kt range. This should result in ample deep-layer shear (~45kts) over the area of interest. With decent moisture in place, sfc temperatures from 70-75F, and mid-level cooling with mid/upper level trough, CAPE values of 750-1200j/kg may be achieved over much of se OK and eastern TX. Currently, NAM does not break out any precip in the region until near dark on Thursday evening because of capping/subsidence issues but synoptic features could come together to allow storms to fire before dark if the trend in the models hold. Will update tomorrow...

Friday 14th
Strong, persistent westerly flow at mid/upper levels will continue to send disturbances into the central and southern plains extending into the Mississippi valley. At the sfc, another low will likely form somewhere in western OK. Much of the evolution for this day depends on how the Thursday event turns out. If moisture is not pushed to far south/east, deepening sfc low in OK may pull decent moisture back into regions of central/north-central/northeast OK with almost easterly sfc winds along KS/OK border midday. Current area of interest would be in the Ponca City-Bartlesville region near a possible occlusion point from sfc low, dryline, and warm front. (Main sever threat would likely be centered in a se OK/Arkansas/n Louisiana area but terrain is horrible there and this forecast is aimed more toward chaseable areas.) Wherever the warm/occluded frontal boundaries end up will likely be an area of interest. Flow at 500mb and up is very strong and directional wind shear profiles will likely be conducive to rotating storms. Will update tomorrow...

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