Area Forecast Discussion
Issued by NWS Shreveport, LA

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000
FXUS64 KSHV 241209
AFDSHV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
709 AM CDT SUN MAY 24 2015

.AVIATION...
FOR THE 24/12Z TAFS...IFR/MVFR CIGS ARE AFFECTING MOST OF OUR TAF
SITES THIS MORNING WITH SOME SCATTERED CONVECTION SLOWLY TRACKING
ACROSS THE REGION. A LARGER COMPLEX OF CONVECTION IS SEEN WORKING
ACROSS CNTRL AND SOUTH TX ALL IN ADVANCE OF AN UPPER LEVEL STORM
SYSTEM MOVING OUT OF ERN NM INTO WRN TX. THESE SHWRS AND TSTMS
WILL EVENTUALLY AFFECT OUR TERMINALS DURING THE DAY TODAY AS THE
UPPER TROF LIFTS FARTHER NORTH AND EAST. THIS WILL KEEP CIGS IN
THE MVFR RANGE FOR MOST SITES WITH SOME OCCASIONAL VFR PERIODS
POSSIBLE LATER IN THE AFTERNOON AS THE CONVECTION GRADUALLY WRAPS
UP FROM SW TO NE ALONG A TONGUE OF DRIER AIR ALOFT WORKING INTO
THE REGION. CIGS WILL LIKELY FALL FURTHER OVERNIGHT WITH SOME VSBY
RESTRICTIONS ALSO POSSIBLE WITH PATCHY FOG AS STRONG S/SE WINDS
DROP OFF SOMEWHAT AFTER 25/00Z...MAINLY OVER THE EASTERN SITES.
/19/

&&

.PREV DISCUSSION... /ISSUED 531 AM CDT SUN MAY 24 2015/

DISCUSSION...
MORNING SATELLITE AND MOSAIC RADAR IMAGERY DEPICTS A LARGE MCS
OVER CNTRL AND SE TX THIS MORNING...WITH A SECOND SYSTEM FARTHER N
ACROSS N TX/SRN AND ERN OK ALONG AND N OF A WELL-DEFINED MCV THAT
HAS DEVELOPED AND SHIFTED TO THE RED RIVER OF SRN OK. THESE ARE
OUT IN ADVANCE OF THE WELL-DEFINED AND AMPLIFED SHORTWAVE NOTED
ON THE WATER VAPOR IMAGERY SHIFTING ENE ACROSS NM...S OF THE
CLOSED LOW OVER THE CNTRL ROCKIES. A WARM AND INCREASINGLY MOIST
AIR MASS HAS SPREAD BACK N INTO THE REGION SATURDAY
AFTERNOON/EARLY THIS MORNING...AND WILL HELP FUEL CONVECTION AS IT
INCREASES LATER THIS MORNING OVER SE OK/E TX WITH THE APPROACH OF
THE SHORTWAVE ONCE IT ENTERS WCNTRL TX. HAVE ALREADY BEGUN TO SEE
LOW STRATUS DEVELOP/ADVECT N ACROSS THE REGION THIS
MORNING...ALTHOUGH THIS CLOUD SHIELD MAY SCATTER OUT LATER THIS
MORNING ESPECIALLY OVER N LA/SW AR ALLOWING FOR BNDRY LYR HEATING
TO OCCUR...RESULTING IN THE DEVELOPMENT OF MODEST CAPE. STRONG
MAINLY UNIDIRECTIONAL SHEAR ATOP THIS DESTABILIZING AIR MASS
SHOULD HELP INVIGORATE CONVECTIVE DEVELOPMENT ONCE THE LARGE SCALE
FORCING ARRIVES LATER TODAY...WITH A DEEPENING WARM LAYER AND PW/S
OF 1.8-2.0 INCHES RESULTING IN THE POTENTIAL FOR LOCALLY HEAVY
RAINFALL. THE SHORT TERM PROGS ARE NOT AGGRESSIVE AT ALL WITH QPF
AMOUNTS WITH THIS SHORTWAVE AND FEEL THEY ARE UNDERDONE...AND AM
EXPECTING TOTALS OF 1-3 INCHES TODAY/TONIGHT AREAWIDE...FALLING
ATOP ALREADY SATURATED GROUNDS WHERE HEAVY RAINFALL FELL EARLIER
THIS PAST WEEK.

HAVE EXPANDED THE FLASH FLOOD WATCH AREA TO INCLUDE UNION COUNTY
AR AS WELL AS THE REMAINDER OF NCNTRL LA...WITH THE HEAVY RAINFALL
THREAT DIMINISHING QUICKLY FROM W TO E THIS EVENING AS DRY
SLOTTING ALOFT RAPIDLY ENTRAINS NEWD BEHIND THIS SHORTWAVE TROUGH.
ALSO CAN/T RULE OUT ISOLATED SVR CONVECTION TODAY/THIS EVENING
WHERE BETTER DESTABILIZATION OCCURS...WITH DAMAGING WINDS THE
PRIMARY THREAT. SHOULD SEE A BRIEF REPRIEVE IN THE HEAVY RAINFALL
LATE TONIGHT...BUT ROUND TWO WILL SET UP MEMORIAL DAY MONDAY
AFTERNOON/NIGHT AS ANOTHER WELL-DEFINED SHORTWAVE NOW OVER THE
SRN CA COAST...QUICKLY SLIDES E ACROSS THE DESERT SW INTO NRN OLD
MX S OF THE ROCKIES CLOSED LOW...BEFORE LIFTING ENE INTO THE SRN
PLAINS MONDAY AFTERNOON. THIS NEXT SHORTWAVE WILL ALSO BECOME
NEGATIVE TILTED AS IT ENTERS THE REGION MONDAY AFTERNOON DURING
PEAK HEATING...WITH DEEP CONVECTION BECOMING MORE NUMEROUS DURING
THE AFTERNOON/EVENING. SHOULD SEE A LITTLE BETTER HEATING OVER
MORE OF THE REGION MONDAY...RESULTING AGAIN IN MODERATE CAPES
DEVELOPING ONCE DEEP LYR SHEAR/STRONG FORCING ARRIVES FROM THE W.
THUS...A SVR THREAT MAY BE MORE PRONOUNCED MONDAY...WITH DAMAGING
WINDS AGAIN THE PRIMARY THREAT. ANOTHER ROUND OF LOCALLY HEAVY
RAINFALL IS LIKELY WITH THIS SECOND SHORTWAVE AS IT LOADS DURING
THE AFTERNOON/EVENING...WITH QPF/S OF 2-4 INCHES POSSIBLE. THE
FIRST SYSTEM TODAY LOOKS TO ONLY PRIME THE REGION FOR WHAT COULD
BE A WIDESPREAD FLASH FLOOD THREAT LATE MONDAY
AFTERNOON/NIGHT...THUS THE REASON WHY THE FLASH FLOOD WATCH HAS
BEEN EXTENDED THROUGH 12Z TUESDAY.

THE HEAVY RAINFALL THREAT SHOULD DIMINISH BY TUESDAY MORNING AS
DRY SLOTTING ALOFT AGAIN SPREADS QUICKLY ENE BEHIND THE DEPARTING
TROUGH. HAVE TONED DOWN POPS FROM W TO E TUESDAY...WITH FLAT
RIDGING ALOFT EXPECTED TO BUILD OVER THE SRN PLAINS/LOWER MS
VALLEY WEDNESDAY/THURSDAY. DID KEEP LOW CHANCE POPS GOING DURING
THIS TIMEFRAME...ALTHOUGH CONVECTION SHOULD BECOME MORE DIURNAL
IN NATURE. TEMPS SHOULD ALSO RETURN BACK TO NEAR OR ABOVE CLIMO
AS WELL...PERSISTING THROUGHOUT THE REMAINDER OF THE EXTENDED.
GENERAL CONCENSUS AMONGST THE GFS/ECMWF SUGGESTS THAT THE FLOW
ALOFT WILL AGAIN BECOME MORE SW BY THURSDAY AS TROUGHING ALOFT
DEVELOPS OVER THE ROCKIES AND EVENTUALLY THE CNTRL/SRN PLAINS.
THIS SHOULD RESULT IN MORE SCT CONVECTION DEVELOPING FRIDAY
THROUGH NEXT WEEKEND...AND THUS HAVE MAINTAINED MID CHANCE POPS
THROUGH THE PERIOD.

THANKS WFO/S LZK AND LCH FOR COLLABORATION THIS MORNING.

PRELIMS TO FOLLOW BELOW...

15

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  81  70  83  69 /  90  60  70  80
MLU  86  70  82  70 /  60  80  70  80
DEQ  76  68  79  67 /  90  60  70  80
TXK  81  69  82  68 /  90  60  70  80
ELD  83  69  82  68 /  70  80  70  80
TYR  78  71  83  69 /  90  40  80  80
GGG  79  71  83  69 /  90  40  70  80
LFK  79  73  83  70 /  90  50  70  80

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...FLASH FLOOD WATCH THROUGH TUESDAY MORNING FOR ARZ050-051-059>061-
     070>073.

LA...FLASH FLOOD WATCH THROUGH TUESDAY MORNING FOR LAZ001>006-010>014-
     017>022.

OK...FLASH FLOOD WATCH THROUGH TUESDAY MORNING FOR OKZ077.

TX...FLASH FLOOD WATCH THROUGH TUESDAY MORNING FOR TXZ096-097-108>112-
     124>126-136>138-149>153-165>167.

&&

$$

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