Area Forecast Discussion
Issued by NWS Shreveport, LA

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000
FXUS64 KSHV 171617
AFDSHV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
1117 AM CDT FRI APR 17 2015

.DISCUSSION...
KSHV RADAR CONTINUES TO BE QUIET THIS MORNING IN THE WAKE OF THE
OVERNIGHT CONVECTION. WV IMAGERY SHOWS A MID-LEVEL DRY POCKET
MOVING ACROSS OUR REGION ATTM...WHICH HAS ALLOWED FOR SOME PEEKS
OF SUNSHINE FOR SOME AREAS. MOSAIC RADAR SHOWS CONVECTION
INITIATING ALONG THE DRYLINE BACK OVER W CENTRAL TX...AS ANOTHER
VORT ROUNDS THE UPPER LOW. THIS IS EXPECTED TO MOVE EWD
TODAY...AND BRING INCREASING SHWRS/TSTMS BY TONIGHT.

FOR THE UPDATE...HAVE MADE A FEW MINOR ADJUSTMENTS TO MAX
TEMPS...BUT OTHERWISE THE GRIDS ARE IN GOOD SHAPE. UPDATED
PRODUCTS ALREADY OUT. /12/

&&

.PREV DISCUSSION... /ISSUED 653 AM CDT FRI APR 17 2015/

AVIATION...
IFR/LOW MVFR CIGS SHOULD PERSIST ACROSS MUCH OF THE REGION THIS
MORNING...WITH THESE CIGS SLOWLY LIFTING BY LATE MORNING/EARLY
AFTERNOON. VFR CIGS SHOULD LINGER THOUGH THE AFTERNOON...ALTHOUGH
ISOLATED CONVECTION CAN/T BE RULED OUT AS LOW LEVEL MOISTURE
DEEPENS DURING THE DAY DURING PEAK HEATING. HOWEVER...WILL HAVE TO
AWAIT THE NEXT SHORTWAVE EXPECTED TO ROUND THE BASE OF THE FOUR
CORNERS REGION CLOSED LOW FOR SCT TO NUMEROUS CONVECTION TO
DEVELOP THIS AFTERNOON OVER W CNTRL/S TX...WHICH WILL SHIFT ENE
INTO E TX DURING THE MID AND LATE EVENING HOURS. HAVE DELAYED
MENTION OF VCTS FOR THE LFK/TYR/GGG TERMINALS UNTIL THE 01-04Z
TIMEFRAME...WITH THE SW AR/N LA TERMINALS BEING AFFECTED AFTER
05-06Z. ADDITIONAL REDEVELOPMENT SHOULD BE ONGOING BY THE END OF
THE 12Z TAF PERIOD...WITH LOW MVFR/IFR CIGS DEVELOPING/SPREADING
NNW LATE. POOR FLIGHT CONDITIONS WITH LOW CIGS/REDUCED VSBYS IN
CONVECTION SHOULD PERSIST THROUGH MUCH OF SATURDAY...WITH SOME
IMPROVEMENT EXPECTED FROM W TO E DURING THE AFTERNOON AS THE
PARENT SHORTWAVE SHIFTS ENE. ESE WINDS 5KTS TODAY WILL BECOME
LIGHT SE OR LT/VRB AFTER 00Z. /15/

PREV DISCUSSION... /ISSUED 502 AM CDT FRI APR 17 2015/

DISCUSSION...
WATER VAPOR IMAGERY INDICATES THE NEARLY STATIONARY UPPER LOW
SPINNING ACROSS THE FOUR CORNERS REGION WITH ENHANCED CONVECTION
EAST OF THE ROCKIES FROM WRN OK DOWN TO THE RED RIVER IN NW TX.
FARTHER SE IN OUR REGION...CONVECTION HAS WANED SIGNIFICANTLY
WITH SHV RADAR MOSTLY QUIET THIS MORNING AS SOME DRIER AIR ALOFT
WORKS EWD FROM CNTRL TX. THE REMAINDER OF THE MORNING LOOKS TO
REMAIN MOSTLY QUIET BUT EXPECT SHWRS AND TSTMS TO REDEVELOP THIS
AFTERNOON AS WE WARM TO NEAR 80 DEGREES...LEADING TO MODERATE
INSTABILITY WITH FAIRLY STRONG MID-LEVEL LAPSE RATES COMBINED WITH
THE ADDED LIFT AND DIVERGENCE ALOFT DUE TO THE UPPER TROF TO OUR
NW. THIS MAY LEAD TO A FEW STRONG TO POSSIBLY SEVERE STORMS AS SPC
HAS INCLUDED MOST OF NE TX...DEEP E TX AND OUR ADJACENT LA
PARISHES ACROSS TOLEDO BEND IN A MARGINAL RISK WITH HAIL AND
DAMAGING WIND GUSTS THE MAIN AREAS OF CONCERN.

AS WE SHIFT AHEAD TO TONIGHT AND SATURDAY...OUR FOCUS WILL SHIFT
MORE TO A HEAVY RAIN THREAT AS THE UPPER TROF SHIFTS FARTHER EAST
INTO OUR REGION AS THE UPPER LOW EJECTS FROM THE ROCKIES OUT OVER
THE PLAINS. THIS WILL ALLOW ADDITIONAL PACIFIC MOISTURE TO STREAM
IN ALONG THE TONGUE OF INCREASING SW FLOW ALOFT WITH ANOTHER LOW
ADVANCING EAST ACROSS BAJA. COUPLE THAT WITH THE BOUNDARY LAYER
MOISTURE IN PLACE AND A SFC LOW RIDING UP THE TX COAST INTO LA ON
SATURDAY MORNING...AND THE STAGE IS SET FOR A SIGNIFICANT RAINFALL
EVENT THROUGH THE DAY ON SATURDAY. THE HIGHEST RAINFALL AMOUNTS
ARE EXPECTED TO BE ACROSS E TX AND N LA GENERALLY ALONG SOUTH OF
I-20...WITH 1-2 INCHES LIKELY AND SOME ISOLATED 3+ INCH TOTALS. IN
ADDITION...ANOTHER MARGINAL RISK FOR A FEW STRONG TO SEVERE STORMS
WILL EXIST ONCE AGAIN MAINLY ACROSS OUR FAR WRN AND SRN LOCATIONS.
RAIN WILL GRADUALLY TAPER OFF THROUGH SATURDAY NIGHT AND EARLY
SUNDAY IN ADVANCE OF A STRONG COLD FRONT SET TO ARRIVE LATE SUNDAY
AFTERNOON.

AS THE COLD FRONT APPROACHES THE REGION LATE SUNDAY...INSTABILITY
WILL SPIKE AS AMPLE SFC HEATING WILL SEND HIGHS WELL INTO THE 80S.
A COMBINATION OF THE INCREASINGLY UNSTABLE CONDITIONS AND STRONG
LIFT ALONG THE COLD FRONT WILL ALLOW FOR AN INTENSE LINE OF SHWRS
AND TSTMS TO DEVELOP...PROMPTING SPC TO INCLUDE AN ENHANCED SEVERE
WEATHER RISK FOR ALL OF S AR AND MUCH OF N LA ON SUNDAY AFTERNOON
AND EVENING. THE MAIN THREAT WILL BE DAMAGING STRAIGHT-LINE WINDS
ALONG THE LEADING EDGE OF THE FRONT WHERE STORMS ARE LIKELY TO BE
STRONGEST. BEHIND THE FRONT...MUCH COOLER AIR WILL FILTER INTO THE
REGION FOR MONDAY INTO TUESDAY WITH DRY WEATHER PREVAILING THROUGH
AT LEAST TUESDAY MORNING BEFORE A SERIES OF WEAK UPPER LEVEL
DISTURBANCES TRANSITION FROM MEXICO ACROSS TX WITH THE INCREASING
SW FLOW PATTERN ALOFT. THIS WILL KEEP US UNSETTLED THROUGH THE
REMAINDER OF THE EXTENDED WITH LOW CHANCE POPS AND SLIGHTLY ABOVE
NORMAL TEMPERATURES FROM MID-LATE WEEK AFTER THE BRIEF COOL DOWN.
/19/


&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  80  66  78  63 /  40  70  70  50
MLU  81  66  77  64 /  40  60  80  50
DEQ  78  64  76  59 /  40  70  60  40
TXK  78  64  77  61 /  40  70  60  40
ELD  79  65  74  62 /  40  60  80  50
TYR  78  64  78  62 /  40  70  60  40
GGG  79  66  78  62 /  40  70  60  40
LFK  81  66  78  64 /  50  70  70  50

&&

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

$$

12


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