Severe Thunderstorm Warning 76, NWS Lubbock, TX

Area Forecast Discussion
National Weather Service Lubbock TX
234 PM CDT Wed May 20 2020

.SHORT TERM...
Little change in the forecast from this mornings update in regards
to afternoon/evening convection...

Upper level shortwave will make its way into our CWA later this
afternoon helping with destabilization. At the surface a dryline
rests near the TX/NM line with E-SE flow across much of our CWA
helping to maintain 60 dewpoints through much of our area. Later
this afternoon surface dynamics and accompanying downslope winds
will aid in the development of a deep lee surface low across the
TX/NM border. This will effectively force the dryline into our far
western counties. The expectation is that the dryline will
sharpen and provide the surface lift necessary for thunderstorm
development. CAMs now showing a later initiation time around 4pm
CDT near and west of I27. Large hail up to hen eggs (2 inches)
remains justified give large CAPEs and severe parameters. DCAPE
values suggest strong wind gusts as high as 70 mph will also be
possible. This afternoons PWs will be greater than 150% of normal.
This along with our moderate vertical wind shear values and
veering winds indicate flash flooding could be an issue especially
across low water crossings and flood prone areas.

Storms will slowly exit the CWA tonight with CDS seeing the last of
the activity after midnight. Behind today's activity overnight
will be mild with lows dropping into the 60s. Tomorrow, the flow
aloft and at the surface become SWRLY with the development of a
lee-side surface low in the afternoon. This scenario will advect
warm dry air into the CWA warming high temperatures into the 90s
for much of the area. SW flow aloft and at the surface will also
act as a forcing mechanism that will drive the dryline to our
eastern borders tomorrow afternoon. Dryline convection could occur
across the very far eastern Rolling Plains or just to our east.

.LONG TERM...
No major changes in the extended forecast which features several
opportunities for thunderstorms and severe weather.

As alluded to above, the dryline will likely reside off the Caprock
tomorrow afternoon/evening, where it could spark isolated late day
convection. If storms can initiate locally, there will be a severe
weather risk. Friday will be fairly similar, though a weak
convectively aided front may dip into the northern South Plains
early in the day. This front will tend to wash out in the afternoon
with the dryline likely mixing back into the Rolling Plains. Thus
there will be a chance for late day convection again on Friday over
the eastern zones, though it could be just outside of the CWA if
some of the guidance is correct.

As the western trough reloads late week into early this weekend,
backing southwesterly flow aloft and surface pressure falls in the
lee of the Rockies should result in the dryline making less eastward
headway. Current projections have the dryline roughly bisecting the
FA from NNE to SSW by peak heating, where it could provide forcing
for isolated to scattered afternoon/evening convection.

The western trough will translate eastward, emerging over the High
Plains late Sunday. This will send a cold front southward into the
South Plains Sunday afternoon or night. T-storms will likely erupt
as the front interacts with the Gulf moisture along of and ahead of
the dryline, which again is forecast to be positioned N-S somewhere
in the center of the FA. Cooler temperatures and a bout of stratus
will follow on Labor Day. Depending on the timing for the front and
passing upper trough, shower/storm chances could linger into early
next week. This will be highly dependent on if/where an upper low
cuts off from the flow, which currently varies from somewhere
over/near West Texas to Kansas, Oklahoma or East Texas. Obviously,
there is a lot to be worked out here, but we have maintained
decreasing rain/storm chances from Monday through Tuesday, with sub-
mentionable PoPs thereafter.

After a warm/hot start to the extended, temperatures will dip
below average behind the FROPA on Monday. However temperatures
should recover to near or even above average by the middle of
next week...assuming a cutoff low doesn't throw down anchor
overhead.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&

28/23

Hazardous Weather Outlook
National Weather Service Lubbock TX
1120 AM CDT Wed May 20 2020

TXZ021>044-211630-
Parmer-Castro-Swisher-Briscoe-Hall-Childress-Bailey-Lamb-Hale-Floyd-
Motley-Cottle-Cochran-Hockley-Lubbock-Crosby-Dickens-King-Yoakum-
Terry-Lynn-Garza-Kent-Stonewall-
1120 AM CDT Wed May 20 2020

This Hazardous Weather Outlook is for the South Plains, Rolling
Plains and the far Southern Texas Panhandle.

.DAY ONE...This afternoon and tonight.

Scattered strong to severe thunderstorms will develop this afternoon
over areas on the Caprock, with activity moving into the Rolling
Plains during the evening. Thunderstorms later today will have
potential for hail to two inches in diameter, wind gusts to 70 mph,
and localized intense rain and flooding will also be possible.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Thunderstorms will be possible this weekend and into early next
week, some of which may be severe.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed. Please relay any
information about severe weather to the NWS while following local,
state, and CDC guidelines.

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