Winter Weather in Texas, December 30, 2020

Area Forecast Discussion
National Weather Service Lubbock TX
1054 PM CST Tue Dec 29 2020

.AVIATION...
Convective showers and thunderstorms only edging slightly east and
remain from the southern South Plains into the northern Rolling
Plains. Solutions indicate convective instability should weaken
overnight. A strong cold front was diving southward expected to
pass all locations by early Wednesday morning. This will help
enhance mid level clouds and likely to continue precipitation
especially in the KCDS area overnight. Solutions also indicate
risk again of another surge of IFR or LIFR stratus into KCDS
behind this front. We are continuing mention of light snow and
mainly MVFR clouds developing near KPVW and KLBB early Wednesday.
Strong north winds also expected to gust to around 30 mph at
times. RMcQueen

&&

.PREV DISCUSSION... /issued 550 PM CST Tue Dec 29 2020/

AVIATION...
Pacific cold front slicing southeast into the central and eastern
South Plains and northern Rolling Plains early this evening with
modest instability may be able to set off a few thunderstorms near
KCDS and also just east and south of KLBB. Stationary front was just
south of KCDS with areas of stratus that area, expected to thin a
bit as the Pacific front washes through. A strong Canadian Cold
front just entering the northern Texas Panhandle will sweep south
overnight bringing colder air and increasing chances for rain at
KCDS and at least a chance of snow both KPVW and KLBB. Ceilings
will lower all areas behind this front into at least MVFR range
but perhaps IFR. Will look further into the Aviation Flight Rules
later tonight with the next 06Z TAF forecast. RMcQueen

UPDATE...
Added fog to the northern Rolling Plains this evening. Also
mentioned slight chance thunderstorms central and eastern South
Plains this evening and updated winds with the passing Pacific
Cold Front. The Storm Prediction Center has a Marginal risk for
severe thunderstorms across the Rolling Plains into the southern
South Plains. We also updated the Hazardous Weather Outlook for
more specific thunderstorm impacts. RMcQueen

PREV DISCUSSION... /issued 233 PM CST Tue Dec 29 2020/

SHORT TERM...
This evening, ahead of the much talked about upper level storm, a
colder air mass accompanied by another round of precipitation will
affect the CWA. Initially the cold air will move in behind a Pacific
front. As large scale ascent from the trough approaches the area the
front will progress eastward into muggier conditions and collide
with an already established warm front settled across the CWA. This
will produce isolated thunderstorms across the northeastern Texas
Panhandle and Rolling Plains. Parameters remain weak for strong
storms, but weak MUCAPES do warrant the mention of thunder in the
forecast.

Heavy on the heels of the Pacific front a Canadian cold front will
storm southward through the FA overnight. This front will be
accompanied by strong northerly winds and will reinforce our cold
conditions. 20 degrees of cooling behind these fronts will make for
a very cold and blustery Wednesday. Although behind the Canadian
front soundings depict dry lower levels, moist upper and mid layers
in combination with decent mid-layer lift and wet-bulb cooling will
result in widely scattered light wintry precipitation tomorrow. With
a continued SE flow of moisture off the Gulf just to our SE
precipitation will be mainly focused across the Rolling Plains in
the form of a very cold rain with a few flurries here or there.
Everywhere else, where temperatures remain very cold, light snow
is expected. Accumulations tomorrow will remain light as we wait
for the upper level system to mature and move northeastward
tomorrow night into Thursday.

LONG TERM...
The long term portion of the forecast continues to be dominated by
the winter weather potential Wednesday night through Thursday
night, primarily for the eastern third of the forecast area.
Models are consistent in moving a strong closed low across
Chihuahua Wednesday night then taking a sharp turn to the
northeast, crossing the Red River north of the Metroplex late
Thursday night and to the mid-Mississippi Valley by the end of
Friday. A mature deformation zone with a TROWAL extending all the
way around the west side of the center of the low is a prominent
feature that is progged to bring the best snow chances and the
heaviest snow to parts of the area through this period. Of course,
the devil is in the details. The GFS is a further east outlier
amongst the models and would favor areas just to the east of the
forecast area. The WRF-NAM is the warmest in the mid-levels, even
once the trough axis north of the closed low moves overhead with
a warm advection component bringing a pronounced warm nose over
the area which would then favor a healthy mix of sleet and/or
freezing rain for a decent part of the precipitation duration. For
now the ECMWF is the "just right" solution that would favor the
potential for a narrow band of heavy snow. This solution seems to
have been favored by WPC as well. This necessitates a marked
increase in total snowfall amounts for areas east of the Caprock
escarpment, but still mostly in a 2-3 inch range. Any later
adjustments upwards and a watch issuance will have to be
considered.

Precipitation is expected to end before sunrise Friday. A weaker
upper trough with little moisture to tap into will be hot on the
heels of the initial one with little effect on the weather. A
return to a progressive, de-amplified pattern is then on the cards
with a dry forecast and warmer temperatures expected.

&&

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

99/99/05

Hazardous Weather Outlook
National Weather Service Lubbock TX
451 PM CST Tue Dec 29 2020

TXZ021>044-302300-
Parmer-Castro-Swisher-Briscoe-Hall-Childress-Bailey-Lamb-Hale-Floyd-
Motley-Cottle-Cochran-Hockley-Lubbock-Crosby-Dickens-King-Yoakum-
Terry-Lynn-Garza-Kent-Stonewall-
451 PM CST Tue Dec 29 2020

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

.DAY ONE...Tonight.

Isolated to scattered thunderstorms are expected to develop from the
eastern South Plains into the Rolling Plains this evening as a
Pacific cold front moves southeast across the area. These storms may
be capable of hail near an inch in diameter and a few wind gusts
over 50 mph. Late tonight, a second and stronger cold front will drop
through the area with gusty north winds behind it. As temperatures
cool behind this front, any lingering rain will change to snow. Only
light accumulations are expected.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

A strong storm system will continue to affect the region from
Wednesday through Thursday night. Light snowfall accumulations of a
half inch or less are possible Wednesday on the South Plains and
extreme southwestern Panhandle. Wintry precipitation, including
snow, sleet, freezing rain, and rain, is forecast to increase across
the Rolling Plains and the Caprock Wednesday night and continuing
into Thursday night. There is the potential for several inches of
snow accumulation, mainly for areas east of the Caprock escarpment
through this period.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LUBBOCK TX
858 PM CST TUE DEC 29 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0856 PM     HAIL             RALLS                   33.68N 101.38W
12/29/2020  E0.88 INCH       CROSBY             TX   PUBLIC

            HAIL NEAR OR JUST SLIGHTLY LARGER THAN NICKELS IN RALLS
            FROM SOCIAL MEDIA PHOTO.

&&

EVENT NUMBER LUB2000553

MCQUEEN