High Wind in Texas, November 24, 2020

Area Forecast Discussion
National Weather Service Lubbock TX
1127 AM CST Tue Nov 24 2020

.AVIATION...
VFR conditions are expected at all terminals for the next 24
hours. Gusty westerly winds this afternoon and early evening will
lead to the possibility of blowing dust at all terminals. BLDU
could create MVFR conditions during this time. Given the strong
winds an Airport Weather Warning for KLBB has been issued and is
valid from noon until 6 pm. Winds will shift to the north-
northwest and remain gusty after sunset as a cold front pushes
through the area. Winds will begin to decrease after midnight
becoming generally light and backing towards the southwest by the
end of the TAF period.

&&

.PREV DISCUSSION... /issued 602 AM CST Tue Nov 24 2020/

AVIATION...
Low stratus, between IFR and low MVFR, currently affecting the
terminals will quickly clear from west-to-east through the morning
hours. Expect KLBB and KPVW to see VFR return around 14Z, plus or
minus one hour, with KCDS to follow around 16Z. Strong westerly
winds will unfold this afternoon, sustained at 25 to 30+ knots.
Given this, we have issued an Airport Weather Warning for KLBB,
valid from noon until 6 pm. In addition to the wind, expect BLDU,
which could reduce the visibility to MVFR levels at times on the
Caprock during the peak winds this afternoon. High-based
convection will also unfold over the Texas Panhandle this
afternoon, though it should stay north of the northern terminals.
The winds will begin to diminish toward sunset, but a cold front
will provide another period of gusty northerly winds as it moves
through the terminals this evening. There could even be a brief
bout of sub-VFR cigs immediately post-frontal. VFR and lighter
winds will return in earnest late tonight.

PREV DISCUSSION... /issued 344 AM CST Tue Nov 24 2020/

SHORT TERM...
What a place we live where we can go from moist southerly winds,
stratus, areas of fog and isolated to scattered showers and
thunderstorms early this morning to strong and dry westerly winds,
blowing dust and fire weather concerns less than 12 hours later.
That is the world we get to live in today!

The system driving this changeable weather is a potent upper
trough that water vapor shows currently approaching the Four
Corners. It will move steadily eastward, emerging over the
Panhandles this afternoon, then proceeding to deepen and close off
as it lifts to Missouri by 12Z Wednesday. Well in advance of the
system a stout southerly LLJ is transporting mild and moist air
northward across the region, complete with widespread stratus and
perhaps even a few pockets of fog, though breezy surface winds are
now helping to limit the fog potential. In addition, the first
round of deeper lift well in advance of the system has recently
sparked the development of scattered showers and elevated
thunderstorms across the southwest Texas Panhandle and
northwestern South Plains, with additional showers over the
southern South Plains. This activity is racing northeastward, and
should exit all but perhaps our far northeast corner by 12Z.

After the moist start to the day, things will quickly change as a
surface low traverses the combined Panhandles, a dryline and Pacific
cold front race across the South Plains region, and strong wind
fields throughout the troposphere emerge over the southern High
Plains...within the base of the storm system. Veering flow will
quickly scour out the moisture, from west-to-east, with strong
insolation leading to deep mixing. This, in combination with a tight
surface pressure gradient, will result in strong southwesterly to
westerly winds sweeping across the CWA. 850 mb flow, which will
easily be tapped, is progged to be 25-35 knots, while 700 mb flow of
40-45 knots should also be reached at peak heating. This will
support sustained winds of 25 to 35 mph, with gusts to 50 mph, for
most/all of the CWA. Hence, we will be issuing an area-wide Wind
Advisory from 17Z to 00Z. This magnitude of winds will undoubtedly
loft blowing dust too. On the bright side, if there is one,
temperatures will be mild, as highs range from the lower 60s across
the southwest Texas Panhandle to the middle and upper 70s in the
Rolling Plains. The warm, dry and windy afternoon will also increase
the fire danger (see the Fire Weather section below for details).

As the vort max emerges across the southern High Plains and a
secondary cold front plunges through the Texas Panhandle, high-based
convection will develop. The bulk of this activity will stay to our
north, though it is not impossible it could flirt with our far
northern zones during the afternoon. We have raised PoPs across the
southern Texas Panhandle to 10% to account for this, though we have
kept an explicit mention out for now. In general, the winds will
begin to decrease around 00Z with the loss of deep mixing and a
relaxing pressure gradient. However, the secondary front dropping
through the Texas Panhandle will result in a period of gusty
northerly winds as it moves through during the evening. There is a
risk some spots, primarily across the southeast Texas Panhandle and
northern Rolling Plains, could jump back to advisory levels winds
for a short while behind this front. We'll let the next shift
evaluation this possibility.

Eventually the winds will drop off for the entire region as the
system pulls away and a surface high moves in from the west late
tonight. Clear skies, light winds and dry air will allow
temperatures to cool efficiently with lows dropping into the 20s
over most of the Caprock, while lows reach the middle 30s in the
Rolling Plains.

LONG TERM...
The previous forecast assessments remain largely on track, with
minimal adjustment made with this morning's package. As mentioned in
previous discussions, fairly benign weather is in store for mid-week
as the trough departs and a low-amplitude ridge builds in across the
central and southern CONUS. Seasonable, sensible weather is expected
for Wednesday with high temperatures climbing into the lower-middle
60s across the CWA, while warmer and breezy conditions are expected
for Thursday ahead of an approaching polar cold front. Westerly
surface winds at around 10-20 mph should contribute to a fair amount
of adiabatic warming, with dry-bulbs ranging from the middle 60s in
the northwestern South Plains to the upper 70s in the eastern
Rolling Plains (which is ~10-15 deg F above climatological norms).

Precipitation chances, albeit low, increase heading into the weekend
as meridional flow moves over the CWA. Whether or not the associated
mid- and upper-level low is closed or transitions into an open wave
that becomes absorbed into a positively-tilted trough is uncertain
at this time due to limited predictability. Regardless of the
synoptic situation that unfolds, moist isentropic lifting processes
could be quite limited, especially given that the low- and mid-level
moisture may very well be scoured out post-FROPA as the continental
polar airmass builds in. If precipitation were to occur (regardless
of precipitation-type), liquid equivalent accumulations would be
minimal, on the order of a few hundredths of an inch.

Temperatures this weekend will be near or just below climatological
norms, with the potential for mixed- and solid-phase precipitation
during the nighttime hours as the ambient surface and wet-bulb
temperatures fall below freezing. Trends will continue to be
monitored over the next several days, but overall, precipitation
chances are looking quite low for the forecast area this weekend.
Otherwise, fair weather is expected heading into early next week as
northwesterly flow advects over the southern Great Plains with
seasonable conditions.

Sincavage

FIRE WEATHER...
Strong southwesterly to westerly winds are on track to affect the
South Plains region this afternoon. Wind speeds will easily exceed
those required for Red Flag conditions, generally sustained at 25 to
35 mph at their peak mid-afternoon. However, today is starting out
on the moist side, with even scattered showers and isolated
thunderstorms traversing the region early this morning. This means
it will take until sometime after noon before considerable drying
occurs. RH values will dip to around 15% (perhaps just below for a
little while) mid-late afternoon across the central and southern
South Plains and Rolling Plains. ERC levels also are starting out
near or below normal and serve as an additional mitigating factor
for possible critical fire weather conditions. Given this, there is
uncertainty whether wind and humidity will overlay long enough to
generate more than brief critical conditions. Regardless, the strong
wind speeds and relatively dry conditions will result in widespread
elevated fire weather conditions, and will issue a Fire Danger
Statement (RFD) for the entire area. It should also be noted, if
any fire fighting operations are ongoing this evening, a cold
front will move through with an abrupt northerly wind shift and a
period of gusty winds, causing the fire line to quickly change.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 PM CST this evening for TXZ021>044.

&&

99/99/10

Hazardous Weather Outlook
National Weather Service Lubbock TX
347 AM CST Tue Nov 24 2020

TXZ021>044-251000-
Parmer-Castro-Swisher-Briscoe-Hall-Childress-Bailey-Lamb-Hale-Floyd-
Motley-Cottle-Cochran-Hockley-Lubbock-Crosby-Dickens-King-Yoakum-
Terry-Lynn-Garza-Kent-Stonewall-
347 AM CST Tue Nov 24 2020

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

.DAY ONE...Today and tonight.

Westerly winds of 25 to 35 mph, with gusts to 50 mph, will be common
across the South Plains region this afternoon. These strong and dry
winds will also loft areas of blowing dust and create elevated to
briefly critical fire weather. A Wind Advisory is in effect for the
entire outlook area from 11 am to 6 pm. In addition, a Fire Danger
Statement is in effect for the entire region from noon until 7 pm.

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

There is a low probability for widespread hazardous weather.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.