Area Forecast Discussion
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FXUS64 KLUB 221937

Area Forecast Discussion
National Weather Service Lubbock TX
237 PM CDT Mon Apr 22 2019

Surface observations at 2 PM revealed a stationary front stretching
from south of Hobbs to Lamesa to northwest of Haskell. Winds north
of this front have slowly veered more easterly and some northward
displacement to this front is likely, particularly tonight once moisture
advection amplifies in response to a decent SSE low level jet. Thus
far, insolation and instability have been curbed under dense mid
and high clouds, but some pockets of thinning clouds and warmer
temps are evident in Andrews County. Along with weak moisture
convergence pooling along the nearby front, this clearing may
help spur isolated or scattered surface based convection later
this afternoon that could easily spread NE into at least our far
southern row of counties. Favorable wind shear and MLCAPE would
support supercell structures (mainly near the front), but the
bigger story should transition to larger rounds of elevated
convection this evening and overnight as PWATs rise to over 1 inch
across most of the region. With 850-700 mb winds holding from the
south and southeast all night downstream of a mesolow in
southeast NM, the stage appears set for multiple rounds of
training convection generally just north of the stationary/pseudo-
warm front. This large window of favorable lift and PWATs could
easily deposit 1-2" of rain over much of the area, but a widespread
flooding risk does not appear in the cards with this event so we
have refrained from a flood watch for now. PoPs were boosted to
100% overnight from the eastern South Plains northeast to the SE
Panhandle where ensembles, CAMS, and deterministic models are in
great agreement for measurable rainfall. Lulls in precip are likely
at times overnight before another slug of deeper lift arrives
between midnight and daybreak with the arrival of a shortwave
trough currently exiting Arizona.

Following additional rounds of elevated convection Tuesday morning,
the aforementioned mesolow and front will be shunted south ahead
of surface high pressure and PWATs falling to half of their peak
amounts. This should focus afternoon PoPs mainly in our far S-SE
zones outside of the earlier antecedent rains, but if this front
is delayed any then the threat for flooding would certainly
amplify given earlier antecedent rains. Aloft, the left exit
region of a high level jet max should provide further background
ascent with some heavy rains again possible due to storm motions
paralleling the front. Current indications are that the cold front
should be departing our CWA by mid/late afternoon when the window
for more robust convection opens, so the severe threat certainly
looks less favorable tomorrow in our area. PoPs were gradually
scaled lower from N-S in the afternoon and continuing through
tomorrow night as saturated depths erode ahead of dry ridging and
northerly flow. However, the edge of a SW-NE oriented moisture
plume aloft and on/off rain chances should remain largely intact
from our far southern zones into the Rolling Plains as an upper
low tracks eastward across the Permian Basin on Wednesday.
Soundings show only modest instability by this time, so showers
and/or stratiform rain should be the main mode of precip on Wed
before the column dries out on Thu. Dry and much milder
conditions close out the end to week and rally into the weekend
under deep westerly flow with some prospects for precip by early
next week as a dryline ensues ahead of a Canadian front and
progressive upper trough.




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