Severe Thunderstorm Warning 29, NWS Lubbock, TX

Area Forecast Discussion
National Weather Service Lubbock TX
700 PM CDT Mon May 11 2020

.AVIATION...
Main concern this evening is on thunderstorm impacts at the
terminals. Isolated convection has already affected KPVW and KCDS
early this evening, but more widespread convection developing in
eastern New Mexico will likely sweep through most/all of the
terminals later this evening. Strong/severe outflow winds and
pockets of hail will accompany this evening's activity as it
moves southeastward. The main round of storms should be shifting
south and east of the terminals around or after midnight though a
few showers could linger into the early morning hours. A weak
frontal boundary will sag southward overnight, with MVFR to IFR
cigs likely developing north of the boundary. KCDS and KPVW will
have the best chance of these sub-VFR conditions, though they
could also affect KLBB. Another round of convection is possible
Tuesday afternoon/evening, which will be addressed in future TAF
issuances.

&&

.PREV DISCUSSION... /issued 320 PM CDT Mon May 11 2020/

SHORT TERM...
We continue to take a wait and see approach to how things will
unfold this afternoon into tonight.  18Z surface analysis shows low-
level moisture continues to increase across the region on strong
south to southeasterly flow.  Area of elevated showers has developed
across the western South Plains and will continue to move east
through the afternoon.  This may impact storm chances by cooling the
boundary layer across the northern south plains but also increasing
the amount of moisture through the sub-cloud layer.  Models have
missed for the most part the current bout of precipitation which
brings into question whether they will have a good handle on how
things will develop this afternoon.  The overall picture remains
fairly  unchanged with 1000-1500 J/kg MLCAPE expected along the
TX/NM state line where storms are expected to initiate.  Starting
off as isolated storms, these will have the best chance for
producing hail and damaging wind before developing into a line that
moves east through the evening.  There still remains a narrow
window where there could be an isolated tornado, mainly early on in
the storms development AND if any storm can deviate to the right of
a mean southeasterly storm motion. Severe weather will transition
more to a wind threat with time as the line becomes better organized
across the Rolling Plains.  Storms should clear the Rolling Plains
in the early morning hours on Tuesday with potentially some low to
mid-level cloud cover hanging around through Tuesday morning.

Behind the departing shortwave and storms, a weak cold front will
push into the northern Rolling Plains around sunrise eventually
stalling out roughly along a Happy to Jayton line by Tuesday
afternoon.  The dryline will mix a bit further east into the western
South Plains setting up a potential triple point anywhere from the
northern South Plains into NE New Mexico.  Models are starting to
show hints at the potential for another round of storms Tuesday
afternoon into Tuesday night but soundings also show a stronger cap
in place across the Caprock.  The NAM and ARW do break the cap up
around Plainview while the TTU-WRF shows a brief storm near
Muleshoe.  We will have to see how conditions develop tomorrow but
we are forecast to be 8-10 degrees warmer than today which may help
overcome any cap.  Started pulling slight chance PoPs further west
and later shifts may need to also push PoPs west again if signal is
still there for storm potential on the Caprock tomorrow afternoon.

Jordan

LONG TERM...
Chances for dryline convection, especially east of the Escarpment
will increase for tomorrow, Wednesday and possibly Thursday as
well. The upper level flow pattern is compressed with a number of
progressive disturbances embedded, transecting across our area
through the end of the week and into the weekend. Any storms that
initiate tomorrow afternoon/evening will struggle to persist after
midnight. The dryline is expected to position itself approximately
along the I27/87 corridor. Deepest moisture will be off the
Caprock where surface dewpoints approach 60 tomorrow and are
firmly in the 50s on Wednesday and Thursday. CAPE values east of
any developing dryline the next few days will be between 1500/2500
J/kg with weak divergent flow aloft. Bulk shear will be on the low
end for severe, between 30-40kts but certainly suitable for the
climatological peak of our severe weather season. The SPC has much
of the Rolling Plains in a 'Marginal Risk' tomorrow with an even
larger area of 'Slight Risk' extending west over the South Plains
on Thursday in the Day 3 outlook.

A much sharper trough over the west will interrupt the more
progressive pattern by the end of the weekend and into next week.
Of interest in the longterm is a retrograding upper level low over
the deep south at the beginning of next week that positions itself
over east Texas and Louisiana. This should help maintain elevated
boundary layer moisture over much of Texas and possibly mitigate
what could be elevated fire weather concerns of a building ridge
overhead. The reason for the odd retrograding low over the deep
south is what may be our first southern atlantic tropical system
of the season off the Florida coast. Although temperatures are
expected to be slightly above normal, the increased moisture is
holding off any extreme heat in the extended forecast.

&&

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

14/55/23

Hazardous Weather Outlook...UPDATED
National Weather Service Lubbock TX
1131 AM CDT Mon May 11 2020

TXZ021>044-121645-
Parmer-Castro-Swisher-Briscoe-Hall-Childress-Bailey-Lamb-Hale-Floyd-
Motley-Cottle-Cochran-Hockley-Lubbock-Crosby-Dickens-King-Yoakum-
Terry-Lynn-Garza-Kent-Stonewall-
1131 AM CDT Mon May 11 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 thunderstorms are expected to develop near or just east of
the Texas, New Mexico state line this afternoon and move east through
sunset. Initially, these storms will be capable of producing wind
gusts to 70 mph and hail to ping pong ball size. The tornado threat
is low but an isolated tornado may be possible with the initial storm
development. Storms will continue to move east southeast and
eventually develop into a line around sunset near the edge of the
Caprock. As the storms move into the Rolling Plains, the threat will
transition to more of a wind threat with gusts up to 70 mph with
isolated reports of hail up to quarter size.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Periods of thunderstorms will be possible this week into the weekend
across the region. From Wednesday through Saturday, temperatures
will warm and moisture will increase, creating an environment more
favorable for severe weather.

.SPOTTER INFORMATION STATEMENT...

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