FXUS64 KSHV 201718

Area Forecast Discussion
National Weather Service Shreveport LA
1218 PM CDT Mon Aug 20 2018

A frontal boundary moving southeast across the region to bring
VCTS conditions across GGG/SHV/MLU/ELD/LFk terminal sites this
afternoon. Southwest winds 10 to 15 knots and gusty ahead of the
front to become northwest at 5 knots tonight, increasing to 5 to
10 knots on Tuesday. Otherwise, VFR conditions to persist through
the terminal forecast period. /05/


.PREV DISCUSSION... /issued 1037 AM CDT Mon Aug 20 2018/

Cold front, along a line from Nashville Arkansas to Texarkana and
points southward including Longview and Jacksonville Texas, has
been drifting southeast across the region this morning. Upper-
low across the midwest with trough extending south across the
ArkLaTex to generate showers and thunderstorms along frontal
boundary later today. Slight risk of severe thunderstorms with
hail and straight line winds possible across portions of south-
central and southeast Arkansas and north-central and northeast
Louisiana this afternoon. Otherwise, southwest winds today to
increase to around 15 mph with higher gusts, becoming northwest
behind the front. Current forecast is on track. No updates at this
time. /05/

PREV DISCUSSION... /issued 500 AM CDT Mon Aug 20 2018/

SHORT TERM.../Today through Tuesday/

Cool front just north of Red River Valley with prefrontal trough
fairly stnry near I-20 as upper low slowly moves east into MO.
Water vapor shows all the dry mid lvl air streaming out ahead of
the front and deep westerly flow suggests only thin layer of
moisture with fropa. However, instability remains high with LI
values near -10 as mid lvl air much colder closer to upper low.
Showers with prefrontal trough have remained quite sparse, and
thus having lowered pops both in the mrng hours with this trough,
and with the limited moisture in aftn fropa. Still, dewpoint
pooling invok front may raise heat indices over 100 with aftn
highs in lower to middle 90s, with some limited relief possible
from partial cloud cover. Pressure gradients also unseasonally stg
and sw-w winds becmg gusty later this mrng. Feel that winds will
remain slightly below lwa criteria across nrn portions of area and
closer to 10 kts across srn portions of the cwa. Isold pops across
srn portions of area after sunset have been knocked back to
showers as lack of colder air aloft and loss of daytime heating
and limited moisture resulting in meager instability. Expect any
chance at all to diminish durg the day Tuesday with front exiting
region. Despite aftn temps tue rising into the 90s, dewpoints in
the 60s will provide a welcome relief to an otherwise sunny day
with westerly breeze./07/.

LONG TERM.../Tuesday night through Monday night/

As a strong upper level longwave trough of low pressure shifts into
the Great Lakes Region and the Southeast states, the flow aloft will
transition to Northwest as a building upper ridge of high pressure
centered over Southwest Texas amplifies North and expands East. On
the surface high pressure will also be building across much of the
Central and Eastern U.S. providing cooler and drier air into the
Four State Region. The cold front that moved through will be nearing
the Northern Gulf of Mexico early Wednesday morning and by early
Thursday morning will lay along the Atlantic Coast across North
Florida and along the Gulf Coast into the Upper Texas Coast.
Temperatures will briefly be a little cooler but the upper  ridge
ridge will build East through the week providing a mostly dry
period. The only exception would be during the daytime Thursday
across a few counties over Southeast Oklahoma and Southwest Arkansas
as a weak shortwave trough of low pressure embedded in the Northwest
flow aloft may steer convection into the area from Oklahoma. GFS and
ECMWF similar in shifting the ridge aloft over the Four State Region
through the late week keeping any precipitation removed from the
forecast until the day Saturday. A Northern stream shortwave trough
of low pressure will move into the ridge aloft splitting the system
allowing the Western portion of the ridge to rebuild/reform West and
then allow disturbances to round the Southern periphery. However the
ridge regains strength over the forecast area and shifts slightly to
the North and Northeast. Deep layer on-shore flow from the Gulf of
Mexico should result in a return of diurnal thunderstorm chances
through the weekend each day and generally along and South of
Interstate 20./06/.


SHV  73  95  69  94 /  20   0   0   0
MLU  73  94  69  92 /  30   0   0   0
DEQ  67  89  66  89 /  10   0   0  10
TXK  70  91  68  90 /  10   0   0   0
ELD  70  93  67  91 /  20   0   0   0
TYR  72  95  69  95 /  10   0   0   0
GGG  73  95  70  95 /  20   0   0   0
LFK  76  96  70  96 /  30  20   0   0





NWS SHV Office Area Forecast Discussion