Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 251154
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
654 AM CDT Tue Apr 25 2017

.AVIATION...
For the 25/12Z TAF period, VFR conditions prevail for the moment
but stratus to our southwest continues to advect northeast and may
gradually fill in over our western terminals through mid to late
morning. This could result in MVFR cigs over East Texas sites and
possibly SHV/TXK before sufficient mixing occurs with very strong
southerly winds to lift and scatter this low stratus into low VFR
stratocu field by this afternoon. South winds will really ramp up
at 15-20 kts by 15Z with gusts from 25-30 kts, especially through
the afternoon hours. These winds are not expected to drop off much
after 26/00Z as the pressure gradient will remain quite strong as
a surface low and cold front over the Plains shift closer to the
region late in the period. MVFR cigs will gradually redevelop and
expand area wide after sunset through the evening hours as surge
in Gulf moisture increases warm air advection ahead of cold front.

/19/

&&

.PREV DISCUSSION... /issued 344 AM CDT Tue Apr 25 2017/

DISCUSSION...
Both the UA ridge and its sfc counterpart has shifted east of the
Four-State Region early this morning, and due to weak sfc lee
troughing, sfc winds has returned to a srly flow. The nearby sfc
trough will promote a tightened pressure gradient leading to breezy
srly winds by mid-morning today, with speeds of 15-20 mph occurring
particularly across the western 2/3rds of the CWA. The current
Lake Wind Advisory is in effect from 10am - 7pm across southeast
OK, southwest AR, all of east TX, deep east TX and northwest LA,
however with the pressure gradient remaining tightening throughout
the night and no decoupling is expected, have elected to extend
the advisory through midnight.

An uptick in low level moisture is already underway this morning as
dewpoints have improved into the middle to upper 50s across
portions of deep east TX and central LA, which is a 5-10 degree
improvement from 24 hours ago. We will continue to see a moisture
surge today through tomorrow as southwest flow aloft sharpens,
courtesy of an UA trough across the Southern Plains this morning
progged to dig east-southeast across the South Plains late
tonight/early tomorrow morning to across southeast OK and the
ARKLATEX late tomorrow aftn/evening. Model solutions exhibited
convection initiating along and behind a cold front that will
impinge the region from west to east, commencing Wednesday aftn.
Concurrently, UL support will be on the rise, with MUCAPE of
1500-2500 j/kg and 0-6 km bulk shear values of 40-60 kts expected.
This suggests that storms will have the capability of becoming
strong to severe, with hail and gusty winds being the primary
threats. However, if discrete cells are able to develop ahead of
the front /ahead of the line of storms/ we can not ignore the
potential of an isolated tornado or two, given progged low LCL/s
and a notable veering hodograph profile in the lower levels. This
system is not expected to stick around for long as precipitation
will be exiting the region from west to east after midnight
tonight.

A cooler and slightly drier airmass will encompass the area on
Thursday thanks to the aforementioned disturbance/s fropa, which is
further validated by daytime temps dropping from the 80s of today to
the 70s with a few 80s on both Wednesday and Thursday. However, the
atmosphere is expected to recover as low level moisture makes a
return to the region by way of a retreating warm front by Friday.
Daytime temps will soar into the 80s /and perhaps a few 90s/ on
Friday, and daytime destabilization could lead to isolated to
scattered showers and thunderstorms more so along and north of
the warm front across the northern zones. In addition, some
instability and adequate deep layer shear will be in place near
the warm front, thus a few strong to severe storms will be
plausible.

Thereafter, focus will quickly turn to the next possible severe wx
maker due for this weekend. Some fine details still needs to be
ironed out as the current model run iteration of the GFS has slowed
down, but the center of the disturbance latitude placement as it
progresses northeast towards the Great Lakes region throughout the
weekend is quite similar to that of the ECMWF. Hence, long term
solutions may be trying to come to a consensus. Keeping all that
in mind, convection is anticipated to develop ahead of a cold
front Friday night across the northern and northwestern zones. A
line of storms along the front will move in from west to east
Saturday evening/night, and if the rainfall amounts proposed by
the Weather Prediction Center comes into fruition, a localized
flood threat will not be out of the question. The precipitation
attm, is expected to come to an end late Sunday night/early Monday
morning. Thereafter, a gradual warmup will take place with temps
recovering in the 70s and 80s by Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  85  70  79  50 /  10  10  60  50
MLU  82  67  82  54 /   0  10  50  60
DEQ  83  67  74  42 /   0  20  60  20
TXK  84  68  76  47 /   0  20  60  20
ELD  82  67  77  48 /   0  10  60  60
TYR  85  70  79  48 /  10  20  60  20
GGG  85  71  80  47 /  10  10  60  20
LFK  86  73  85  51 /  10  10  60  20

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...Lake Wind Advisory from 10 AM this morning to midnight CDT
     tonight for ARZ050-051-059-060-070-071.

LA...Lake Wind Advisory from 10 AM this morning to midnight CDT
     tonight for LAZ001-002-010-017.

OK...Lake Wind Advisory from 10 AM this morning to midnight CDT
     tonight for OKZ077.

TX...Lake Wind Advisory from 10 AM this morning to midnight CDT
     tonight for TXZ096-097-108>112-124>126-136>138-149>153-
     165>167.

&&

$$

19/29



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