Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 211535
AFDSHV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
1035 AM CDT THU AUG 21 2014

.DISCUSSION...
LATEST VIS SATELLITE IMAGERY SHOWING EXPANSIVE STRATOCUMULUS DECK
ENCOMPASSING MOST OF THE FOUR STATE REGION THIS MORNING. CUMULUS
IS TAKING ON MORE OF A HORIZONTAL ROW APPEARANCE WHICH IS
INDICATIVE OF SOME MIXING BEGINNING TO TAKE PLACE IN THE LOWER
ATMOSPHERE AS HEATING TAKES PLACE. AS A RESULT...EXPECT SOME PEEKS
OF SUN TO BEGIN OVER THE NEXT COUPLE HOURS WITH EVENTUALLY SKIES
BECOMING PARTLY CLOUDY ACROSS THE REGION.

STRONG WINDS IN THE LOWEST 5KFT ALLOWED THE STRATUS TO MOVE
QUICKLY NORTHWARD AND CONDENSE EARLY THIS MORNING AND WE ARE
STARTING TO SEE SOME OF THIS MIX DOWN ACROSS NE TX THIS MORNING
WITH STRONGER WIND GUSTS NOTED NORTH AND WEST OF THE I-30 CORRIDOR
ACROSS TX.

LOOKING AT NEW RAW 12Z NAM OUTPUT...THERE REMAINS A WEAK SHEAR
AXIS ACROSS OUR EASTERN MOST ZONES EARLY THIS MORNING. WEAK BUT
OBVIOUS 850-700MB THETAE AXIS ALSO RESIDES ACROSS THIS GENERAL
AREA AND AS A RESULT...THIS WILL MOST LIKELY BE THE FAVORABLE
REGION TO SEE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS LATER
TODAY.

OTHERWISE...ONCE THE CLOUDS THIN...SHOULD HAVE NO PROBLEMS GETTING
TEMPERATURES TO REACH FCST MAX TEMPS WITH 15Z OBSERVATIONS ALREADY
RUNNING SOME 1 TO 3 DEGREES ABOVE THOSE EXPERIENCED ON WEDNESDAY
ATTM.

NO UPDATE NECESSARY TO THE FORECAST THIS MORNING.

13

&&

.PREV DISCUSSION... /ISSUED 435 AM CDT THU AUG 21 2014/

DISCUSSION...
11-3.9U SATELLITE IMAGERY THIS MORNING INDICATES A VORTICITY MAXIMUM
OVER NCNTRL LA...WHICH IS ALONG A ELEVATED WEAK SHEAR AXIS NOTED ON
THE WATER VAPOR LOOP EXTENDING FROM SE TX ACROSS NCNTRL LA INTO CNTRL
MS/NRN AL. THIS FEATURE HAS MAINTAINED AN EXTENSIVE AC CANOPY THIS
MORNING OVER MUCH OF NCNTRL LA...WHICH ARE THE CONVECTIVE REMNANTS OF
THE ISOLATED SEABREEZE CONVECTION THAT AFFECTED THESE AREAS WEDNESDAY
AFTERNOON AND EVENING. A WEAK UPPER LOW NOTED ON THE WATER VAPOR LOOP
NOW AFFECTING THE ERN MX COAST S OF BRO HAS ALREADY RESULTED IN
ENHANCED ONSHORE FLOW WHICH HAS LED TO INCREASED MOISTURE CONVERGENCE
ALONG A W TO E SFC TROUGH WHICH LIES NEAR THE I-10 CORRIDOR. THIS HAS
RESULTED IN ISOLATED CONVECTION DEVELOPING/STREAMING N ACROSS SW
LA...BUT HAVE WEAKENED WHERE SFC CONVERGENCE IS LOST FARTHER N OF THE
SFC TROUGH. THE PROGS DO WEAKEN THE VORT MAX LATER TODAY AS THE CENTER
OF THE 500MB RIDGE BEGINS TO BUILD NNW INTO THE LOWER MS VALLEY...BUT
SHOULD STILL SEE ANOTHER DAY WHERE SEABREEZE CONVECTION WILL AFFECT
THE SRN ZONES MAINLY DURING THE AFTERNOON/EARLY EVENING. GIVEN THE SSW
850-700MB FLOW...THE SEABREEZE SHOULD NOT PUSH AS FAR N ACROSS E TX/NW
LA AS IT HAS IN RECENT DAYS...BUT THE HRRR AND GFS SUGGEST THAT THE
CONVECTION COULD PUSH FARTHER NNE ACROSS THE ERN SECTIONS OF NCNTRL
LA. FOR THAT REASON...HAVE EXTENDED SLIGHT CHANCE POPS FARTHER N INTO
LINCOLN/UNION/OUACHITA PARISHES THIS AFTERNOON/EVENING...BUT A
STABILIZING BNDRY LYR FROM THE LOSS OF HEATING RESULTS IN THE QUICK
DISSIPATION OF THE CONVECTION. DID ALSO INCLUDE LOW CHANCE POPS FOR
THE SE SECTIONS OF NCNTRL LA...WHERE EXTRAPOLATION OF THE CURRENT
CONVECTION WILL LIKELY RESULT IN ADDITIONAL OUTFLOW BNDRYS THAT WILL
FOCUS MORE SCT DEVELOPMENT ESPECIALLY WHEN PEAK HEATING IS REACHED.
WITH THE AC SHIELD GRADUALLY THINNING BY AFTERNOON...AND THE MORNING
LOW STRATUS QUICKLY LIFTING THIS MORNING...MAX TEMPS TODAY SHOULD BE
NEAR IF NOT SLIGHTLY WARMER THAN WHAT WAS OBSERVED WEDNESDAY.

THE HEAT IS ON FRIDAY THROUGH EARLY NEXT WEEK AS THE CENTER OF THE
UPPER RIDGE RESIDES IN VC OF OUR REGION OVER LOWER MS VALLEY. THIS
SHOULD RESULT IN MAX TEMPS CLIMBING INTO THE UPPER 90S AREAWIDE BY THE
WEEKEND...WITH A FEW TRIPLE DIGIT TEMPS NOT OUT OF THE QUESTION OVER
PORTIONS OF THE REGION. EVEN WITH THE 700MB RIDGE CENTERED OVER ERN AR
SUNDAY...AMPLE SOIL MOISTURE OVER ERN LA/SE AR SHOULD HELP MAINTAIN
TEMPS BELOW THE CENTURY MARK...BUT RESULT IN HIGHER DEWPOINTS/HEAT
INDICES SUCH THAT A HEAT ADVISORY MAY BE NEEDED FOR PORTIONS OF NCNTRL
LA/S AR THIS WEEKEND. HAVE TRENDED SLIGHTLY COOLER THAN MAVMOS THIS
WEEKEND...ESPECIALLY GIVEN ITS WARM BIAS FOR THE LAST SEVERAL WEEKS.

THE PROGS CONTINUE TO SHIFT THE UPPER RIDGE CENTER FARTHER NE INTO THE
MID MS VALLEY BY MONDAY WITH THE RIDGE AMPLIFYING INTO THE GREAT LAKES
REGION...WITH THE EXTREME HEAT BEGINNING TO WEAKEN ITS GRIP ON OUR
AREA. BUT THIS WILL BE GRADUAL...UNTIL WEAKNESSES BENEATH THE RIDGE
CENTER ARE ABLE TO MIGRATE W ACROSS MS/SE LA MONDAY...WHICH MAY TOUCH
OFF ISOLATED CONVECTION OVER MUCH OF NCNTRL LA/DEEP E TX. WITH THESE
WEAKNESSES NUDGING CLOSER TO OUR REGION BY TUESDAY...MORE IN THE WAY
OF SCT CONVECTION IS EXPECTED OVER NCNTRL LA/DEEP E TX...WITH ISOLATED
CONVECTION POSSIBLE FARTHER W. FORECAST CONFIDENCE DIMINISHES
THEREAFTER...WITH THE GFS SUGGESTING AN UPPER TROUGH QUICKLY SHIFTING
E ACROSS THE PLAINS WEDNESDAY AND ACROSS THE SRN PLAINS/LOWER MS
VALLEY THURSDAY. MEANWHILE...THE ECMWF REMAINS STOUT WITH THE RIDGE
CENTER ACTUALLY RETROGRADING W BACK ACROSS THE CNTRL CONUS...WITH A
MUCH SLOWER AND WEAKER TROUGH PASSAGE /IF ANY AT ALL/ BY NEXT WEEKEND.
FOR NOW...HAVE MAINTAINED SLIGHT CHANCE POPS THROUGHOUT THE REMAINDER
OF THE EXTENDED...WHILE KEEPING NEAR NORMAL TEMPS THROUGH THE PERIOD.

PRELIMS TO FOLLOW BELOW...

15

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  96  74  97  74  98 /  10  10   0   0   0
MLU  94  73  96  73  97 /  20  20   0   0   0
DEQ  94  72  95  72  96 /   0   0   0   0   0
TXK  95  74  96  74  97 /   0   0   0   0   0
ELD  94  72  96  73  97 /  10  10   0   0   0
TYR  97  75  97  75  97 /  10  10   0   0   0
GGG  95  74  96  74  97 /  10  10   0   0   0
LFK  96  74  97  74  97 /  20  10   0   0   0

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&

$$

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