Area Forecast Discussion
Issued by NWS Shreveport, LA
FXUS64 KSHV 211534
Area Forecast Discussion
National Weather Service Shreveport LA
1034 AM CDT Tue Mar 21 2017
Updated to remove early morning patchy fog across southern cwa.
Also tweaked sky cover and raised wind speeds a tad to account for
mixing in dry airmass. Left temps alone as very dry airmass to
also allow for quick warming, thus mid 80s across much of area may
yet be achieved./VII/.
.PREV DISCUSSION... /issued 713 AM CDT Tue Mar 21 2017/
For the 21/12Z TAF period, some patchy low stratus is advecting
northward this morning and will create intermittent MVFR ceilings
along and south of our I-20 terminals. These cigs will gradually
lift and scatter later this morning so expect VFR conditions to
resume areawide after 15Z. Southwest winds will increase closer to
10 kts or higher with occasional gusts near 20 kts, mainly across
our East Texas terminals. Winds will drop off after 22/00Z and low
clouds will be quick to redevelop overnight with patchy fog also
a good possibility ahead of an approaching cold front, which will
be backdooring in from the northeast. The front may advance into
ELD prior to the end of this TAF period, but it will largely not
be a factor until after 22/12Z while low cigs/vsbys linger ahead
of the front through Wednesday morning.
PREV DISCUSSION... /issued 255 AM CDT Tue Mar 21 2017/
Persistent srly sfc flow encompassing the Four-State region early
this morning, has once again resulted in the development of a
stratus deck across central LA /where the best moisture axis
resides/, which is anticipated to spread northeastward to across
portions of northern LA through daybreak. Can not rule out the
development of patchy light fog though if past events /such as last
night/ are much of a reference, low level cloud cover will likely be
the rule. Any lingering low clouds will scour out by mid-morning.
A 1040 mb sfc ridge across the Northern Plains/southern Canada
will send down a cold front that is progged to become quasi-
stationary north of the CWA today, but will finally backdoor to
across southeast OK, southwest AR and extreme northeast TX late
tonight. Given the moist low levels, model solutions hint at
showers and perhaps a few thunderstorms developing along the
front, before it retreats north as a warm front on Thursday.
Could still see some lingering drizzle/very light rain across the
aforementioned area Thursday morning.
Main focus in the extended forecast continues to be chances for
widespread showers and thunderstorms on Friday, as well as chances
for storms to become strong to severe. Long term solutions are in
good agreement in showing a Pacific UA trough that is progged to
move east-northeast across the Southern Rockies and onto the
Plains, during which time becoming a closed UA low. A line of
thunderstorms will develop along a dryline across the Red River
Valley and nearing east Texas late Friday morning, and will
affect southeast OK and the ARKLATEX by late aftn/early evening.
It will move from west to east clearing the FA late Friday
night/early Saturday morning, with lingering showers on Saturday.
Steepened lapse rates, MUCAPE values of 500-1000 j/kg and 0-6 km
bulk shear of 40-60 kts raises concern for storms to become
organized, and bring about the potential for hail, damaging wind
gusts and isolated tornadoes. The Weather Prediction Center is
maintaining moderate rainfall with this event, with expected
rainfall amounts of 1.00-3.00 inches valid from 12Z Friday-12Z
Sunday. Thereafter, the synoptic pattern appears to become
progressive with another UA shortwave, albeit weaker than Friday`s
disturbance, that will bring renewed chances for precipitation
early next week.
Nearing/equating record breaking warmth /middle to upper 80s/ is
expected once again today as the UA ridge nudges east towards the
region. The presence of the backdoor cold front tomorrow will
result in an obvious temp gradient of daytime temps in the 60s and
70s across the north to the 80s across the south. A brief
reprieve will occur on Thursday /70s and 80s/ given the front
retreating as a warm front, but the anticipated widespread
thunderstorms and increased cloud cover on Friday will cause temps
to drop into the 70s. A gradual warm up will take place early
next week /70s and 80s/ despite the return of precipitation.
.PRELIMINARY POINT TEMPS/POPS...
SHV 86 60 78 59 / 0 10 10 10
MLU 86 58 76 56 / 0 10 10 10
DEQ 85 58 69 52 / 0 20 20 10
TXK 85 58 72 54 / 0 10 20 10
ELD 85 58 71 52 / 0 10 10 10
TYR 85 61 80 60 / 0 10 10 10
GGG 85 60 78 59 / 0 10 10 10
LFK 86 61 84 60 / 0 10 10 0