Area Forecast Discussion Issued by NWS Shreveport, LA
000
FXUS64 KSHV 171136
AFDSHV
Area Forecast Discussion
National Weather Service Shreveport LA
636 AM CDT Sun Mar 17 2024
...New AVIATION...
.SHORT TERM...
(Sunday through Monday Night)
Issued at 421 AM CDT Sun Mar 17 2024
The early morning radar imagery has been largely void and quiet
across the region, with the first wave of convection having exited
the area to the E shortly after midnight. However, the morning
water vapor imagery indicates the next shortwave just NE of the TX
Big Bend region well ahead of the Srn AZ closed low now beginning
to eject NE, which has driven a large complex of convection over
S and SE TX that is progressing ENE towards our region. The
various short term progs are in agreement with this convection
spreading into Lower E TX and portions of N LA generally along/S
of the AR/LA border by and after daybreak, but should generally
decrease from W to E late this morning through mid-afternoon with
the departure of this shortwave trough. The Nrn edge of the
convection though should not spread too far N into extreme NE
TX/SW AR given the proximity of the H850 trough, which currently
straddles the Red River Valley into the Nrn sections of SW AR, and
remains progged to sink S through the region this morning, and
exiting to the S by early afternoon. This trough is in advance of
a cold front which is analyzed this morning from Cntrl OK E into
NW and NCntrl AR, which will sink S into McCurtain County OK and
the Nrn sections of SW AR after daybreak, becoming more diffuse as
it enters E TX and N LA later today. Pressure rises from the NNW
will result in cooler and drier air gradually advecting S later
this afternoon and especially overnight, with the post-frontal low
clouds diminishing from N to S later this afternoon through
tonight.
Concentrated highest (categorical) pops this morning generally
S of I-20 across E TX/N LA, before tapering back pops from W to E
this afternoon. While no severe weather is expected with this convection,
mid level lapse rates will be sufficient enough to support some
embedded thunder, with brief heavy rainfall possible in the
stronger storms. Fortunately, this rain will fall over areas which
have seen lighter storm totals over the last couple of days than
areas farther N over portions of extreme E TX/Srn AR, which
observed widespread flash flooding Friday morning.
Should finally see a prolonged period of drying tonight through at
least midweek this week, as deep longwave troughing carves S
through the Plains into the MS Valley and SE states. In fact, a
return to below normal temps are expected areawide Monday with
brisk Nrly winds, before winds quickly decouple by evening as
Canadian sfc ridging settles SE into the region. This will set the
stage for good radiational cooling and abnormally cold and frosty
conditions areawide late Monday night/Tuesday morning, with temps
settling well into the 30s areawide. The latest guidance suggests
that near and subfreezing temps are expected over SE OK/SW
AR/portions of extreme NE TX, and possibly extreme Nrn LA
(bordering the AR border), with high enough confidence such that a
Freeze Watch has been issued for these areas late Monday
night/Tuesday morning. However, rex blocking over the Desert SW
will hold firm through much of Tuesday with the closed AZ low
expected to tap another wave of subtropical moisture Monday night
such that areas of thin cirrus should begin to increase over E TX
overnight before eventually spreading through the remainder of the
area Tuesday.
Thank you WFO`s LZK/JAN for coordination this morning.
15
&&
.LONG TERM...
(Tuesday through Sunday)
Issued at 421 AM CDT Sun Mar 17 2024
Sfc ridging will settle S through the area Tuesday, but will
result in a warming trend commencing, albeit temps should still
remain slightly below normal. This warming trend will continue
Tuesday night with min temps expected to be some 10-15 degrees
milder than earlier that morning, as the cirrus shield thickens
and a light SSW low level flow returns on the backside of the sfc
ridge and it drifts E along the Gulf Coast. Low level moisture
return should commence Wednesday, especially as the flow begins to
increase in response to the closed low ejecting out across NM
while opening up into a trough and advancing through the Red
River Valley and N TX. There still remains some uncertainty though
as to the strength of this ejecting trough, with the GFS more
amplified than the ECMWF and thus, more bullish with the extent of
developing convection as the trough traverses the region
Thursday. Fortunately, sfc based instability looks to remain
limited given the lack of prolonged Srly flow, but confidence has
increased enough with QPF`s such that pops were raised to likely
across the Wrn half of the region Thursday, with the expectation
that convection may be more scattered farther E as the shortwave
begins to dampen out. Did maintain a diminishing trend in pops
Thursday night with the departure of the shortwave, although a new
warming trend will commence by week`s end with increased
insolation. Not quite buying the cooler temps the GFS is
advertising Friday into next weekend given its stronger
amplification of the aforementioned trough, with even the ensemble
guidance suggesting warmer temps.
Quiet conditions will return for next weekend, with additional
warming expected, as temps return back above normal. Will have to
keep a close eye with the potential longwave troughing next
weekend (per the ECMWF) over the Rockies/Plains, which may result
in an increase in prolonged convection late next weekend into the
start of the new work week.
15
&&
.AVIATION...
(12Z TAFS)
Issued at 627 AM CDT Sun Mar 17 2024
For the 17/12Z TAFs, MVFR to IFR CIGs will continue through much
of the day for southern ArkLaTex airspace, with visibilities
impaired by ongoing areas of heavy rainfall. Conditions will begin
to improve through the late morning and afternoon, especially
across northern and western airspace, followed by improvement to
the southeast as showers and storms depart the region. Winds will
be northwesterly at speeds of 5 to 10 kts with gusts of up to 20
kts possible, becoming more northerly late in this forecast period.
/26/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 67 46 63 36 / 60 0 0 0
MLU 65 44 60 33 / 80 0 0 0
DEQ 66 36 58 30 / 10 0 0 0
TXK 67 41 59 34 / 20 0 0 0
ELD 65 39 59 30 / 40 0 0 0
TYR 68 45 62 38 / 40 10 0 0
GGG 67 46 62 36 / 50 10 0 0
LFK 68 49 66 38 / 100 10 0 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...Freeze Watch from late Monday night through Tuesday morning for
ARZ050-051-059>061-070>073.
LA...Freeze Watch from late Monday night through Tuesday morning for
LAZ004-006.
OK...Freeze Watch from late Monday night through Tuesday morning for
OKZ077.
TX...Freeze Watch from late Monday night through Tuesday morning for
TXZ097.
&&
$$
SHORT TERM...15
LONG TERM....15
AVIATION...26