719
FXUS64 KSHV 230449
AFDSHV
Area Forecast Discussion
National Weather Service Shreveport LA
1049 PM CST Sun Dec 22 2024
...New AVIATION...
.UPDATE...
Issued at 1004 PM CST Sun Dec 22 2024
Stratocumulus continues to expand farther eastward into NE Texas,
SE Oklahoma, and parts of SW Arkansas. This trend looks to persist
through the remainder of this evening into the overnight hours so
did beef up sky cover across these areas for the duration of the
overnight period. Otherwise, the forecast appears to be largely on
track with no additional changes needed at this time. All updated
text products have been issued to reflect the minor adjustments to
cloud cover.
/19/
&&
.SHORT TERM...
(This evening through Monday Night)
Issued at 129 PM CST Sun Dec 22 2024
In the mid and upper levels this afternoon a broad trough
encompasses most of the NE PAcific, with the downstream pattern
featuring a weak ridge over the West Coast and potent shortwave
trough over the Northern Rockies. Further downstream, northwest
flow resides over the central US and MS Valley, with a few
shortwave troughs over TX giving way to broader troughing over
the Eastern Seaboard and adjacent Atlantic waters. Near the
surface, expansive high pressure is noted east of the MS, down
into the ArkLaTex and all the way NE into the Mid Atlantic. Lee
cyclogenesis is also underway across the Central Plains with high
pressure noted across the large majority of the West.
After a cold start to the morning across the Four State Region,
temperatures have slowly been moderating into the 50s as
aforementioned surface high pressure shifts slowly east and low
level winds shift lightly out of the SE. Skies are clear across
the majority of the area, with the exception being the northern
half of East TX, SE OK and portions of SW AR where a subtle
shortwave trough at H5 is pushing a SCT-BKN mid level cloud deck
across these areas. These clouds will scatter some into the
evening hours while also pushing east into NW LA and S AR.
Overnight tonight, surface high pressure influence will continue
to slide slowly east, aiding by the development of a sfc low over
the OK/TX panhandles and an increasing pressure gradient between
the two features across the eastern half of TX. Conditions will be
favorable with this developing pattern for moisture to begin to
return across western zones. Expect a temperature gradient with
lows tonight, with clear skies and less airmass modification from
the TX/LA and TX/AR borders eastward where lows will drop back
into the 30s. Across E TX and perhaps SE OK, lows will be in the
low 40s, with some lower level clouds cover moving in
towards/around sunrise.
The area will continue to lose surface high pressure influence on
Monday, with the sfc low over the OK/TX panhandles moving south
into north-central TX. Associated sfc boundaries will develop in
its vicinity, including a dryline to its south. Winds will be a
bit breezier out of the SE on Monday provided the continued
pressure gradient. This will also be enough for a more substantial
modification in the airmass for all locations, with high
temperatures in the mid to upper 60s (upper 50s to near 60 across
SE OK and northern AR counties given higher cloud cover). The
expected track of the sfc low will be near the Red River along the
TX/OK border, aided by a mid level disturbance in the same general
vicinity. With upper level support, a few showers appear possible
near the warm front across far northern zones by Monday evening
and continuing Monday night. Limited instability is currently
expected to prevent thunderstorms.
Conditions at the end of the short term forecast period will be
setting the stage for a much more active pattern across the
ArkLaTex for the long term.
Kovacik
&&
.LONG TERM...
(Tuesday through next Saturday)
Issued at 129 PM CST Sun Dec 22 2024
The long term forecast period continues to trend active, with the
potential for strong to severe thunderstorms around and after the
Christmas holiday.
To begin the period on Tuesday, the mid and upper levels will
feature a weak split-flow pattern, with low amplitude/broad
troughing encompassing the Southern Plains. The same shortwave
trough and sfc cyclone mentioned at the end of the short term
period will continue to advance eastward/maybe slightly southward
towards the CWA Tuesday morning. This will make for increasing
rain chances from far West LA and AR westward through E TX and SE
Ok through the day on Tuesday. The current projected track of the
sfc low will aid in rising dewpoints across these locations, into
the 50s for most and potentially the low 60s across far SW E TX
counties. This along with steepening mid level lapse rates near
7C/km should allow for some destabilization, with MLCAPE values
projected to be around 500 J/kg. This may pose a threat for
isolated severe thunderstorms, especially where the best moisture
is located across Deep E TX, however, the limiting factors will be
the instability and deep layer shear. This will keep the threat
marginal at best and this coincides well with the current forecast
from SPC.
Tuesday night, what limited instability/CAPE that materialized
Tuesday afternoon and evening will decrease quickly into the
overnight hours. Steep lapse rates, supported by the passing mid
and upper level trough will still support the threat for isolated
thunderstorms, but with the overall lack of appreciable severe
weather ingredients, impacts are unlikely.
This system will exit the area on Christmas morning, taking the
associated atmospheric dynamics with it. Areas of rain could be a
bit stubborn to push east of North Central LA and S AR through the
morning hours, but largely expect quiet conditions for most of the
area. A shortwave ridge of high pressure will pass across the area
in the mid and upper levels on Christmas Day, which will be
amplified by an deepening shortwave trough which will be rapidly
diving SE from the Great Basin vicinity into the Southern Rockies.
The forecast will reflect a quiet weather day for the Christmas
holiday, with no airmass change with the departing weather system
yielding highs in the low 60s north to around 70 south and
dewpoints in the upper 50s to near 60.
The forecast pattern trends more interesting on Thursday. The
rapidly moving shortwave trough over the Southern Rockies will
advance towards the OK/TX panhandles, resulting in the quick
development of a sfc reflection in the same general vicinity.
There is still some discrepancy in the deterministic guidance as
to where this system as a whole will track. While this will be
important, it still appears that there will be a severe weather
threat across the ArkLaTex on Thursday. A cold front will be
approaching the area on Thursday. Convection is expected to
develop/be ongoing along and ahead of the cold front Thursday,
moving west to east through the day and likely moving into the
area in the afternoon hours. While instability does not look
particularly strong despite near 60 dewpoints and mid level lapse
rates 7-7.5C/km, on the order of 1000J/kg, shear will
substantially increase. These ingredients will be enough to
support the threat for severe weather the second half of the day
on Thursday and into the overnight hours. As mentioned, the track
of this system will be important, with the track of the current
00z and 06z ECMWF supporting a more aggressive severe threat and
the track of the 06z and 12z GFS supporting a more marginal
threat. That said, it is important to keep in mind that either
track supports a severe weather threat at this point in time.
The severe threat will decrease late Thursday night into Friday,
however, another threat for severe weather will exist Friday into
Saturday as another shortwave trough pushes across the Southern
Plains and ArkLaTex. Another frontal system will develop in
response to this system, with little change in the atmospheric
ingredients from the prior day.
This system will be the last in the series, with dry NW flow aloft
and sfc high pressure moving into the area to close out the
weekend and the long term forecast period. Will not see a big
change in air temperature behind this last departing system so
expect generally mild conditions to round out this forecast period.
Kovacik
&&
.AVIATION...
(06Z TAFS)
Issued at 1041 PM CST Sun Dec 22 2024
Low clouds are quickly arriving at local terminals this evening,
working from west to east. BKN/OVC CIGs will continue to influence
area terminals overnight and into Monday AM. Though the low CIGs
will be in place, VFR looks to remain present, though brief MVFR
conditions may prevail across the ETX terminals, and maybe as far
north of KTXK. Thinking remains the same as the previous TAF
package for clouds to work as far east as SHV/ELD, with a mix of
SCT/BKN based on hi-res guidance this evening and cross section
analysis. Through the period, S/SE terminal winds will continue,
generally between 5-10kts.
KNAPP
&&
.SPOTTER INFORMATION STATEMENT...
Issued at 139 AM CST Sun Dec 22 2024
Spotter activation is not expected through tonight.
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 38 66 51 69 / 0 0 0 60
MLU 32 64 43 69 / 0 0 0 10
DEQ 36 56 48 58 / 0 10 50 90
TXK 39 62 51 65 / 0 0 20 80
ELD 33 63 45 66 / 0 0 0 40
TYR 46 68 54 68 / 0 0 10 80
GGG 42 66 52 68 / 0 0 10 70
LFK 42 68 53 71 / 0 0 0 50
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
SHORT TERM...23
LONG TERM....23
AVIATION...53
NWS SHV Office Area Forecast Discussion
