264
FXUS64 KSHV 072142
AFDSHV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
342 PM CST SAT NOV 7 2009
DISCUSSION
AS EXPECTED...THE STRATOCU FIELD HAS ERODED ACROSS THE REGION EARLY
THIS AFTERNOON...ALTHOUGH CHANGES ARE IN THE OFFING...AS THE GULF
COAST REGION WILL BE AFFECTED BY THE REMNANTS OF TS IDA...AS IT
BECOMES DIRECTED TOWARDS THE COAST AHEAD OF THE OLD MX LOW DRIFTING E
THIS AFTERNOON. FLAT RIDGING PERSISTS FROM THE SRN PLAINS E INTO THE
SE STATES THIS AFTERNOON...WITH THE LOW TO THE W EXPECTED TO OPEN UP
OVERNIGHT...GRADUALLY ENHANCING DEEP LYR MOISTURE RETURN
SUNDAY/SUNDAY NIGHT. HAVE DELAYED THE ONSET OF POPS UNTIL SUNDAY
NIGHT...WITH MID/HIGH BASED MOISTURE EXPECTED TO INCREASE QUICKLY
AFTER 12Z SUNDAY AHEAD OF AN INITIAL SHORTWAVE THAT WILL EJECT OUT
AHEAD OF THE TROUGH. BUT IN THE MEANTIME...AS WAS THE CASE THIS
MORNING...CAN/T RULE OUT PATCHY FG DEVELOPING ONCE AGAIN ALONG THE
OUTER PERIPHERY OF THE SFC RIDGE STILL IN PLACE...WITH THE EXTENT
DICTATED BY THE NWD PROGRESSION OF THE CIRRUS SHIELD OVER THE
NRN/GULF/SRN LA AND SE TX.
FOCUS WILL THEN SHIFT TO THE REMNANTS OF IDA...AS IT IS EXPECTED TO
BECOME SUBTROPICAL AS IT BECOMES PICKED UP BY THE TROUGH MONDAY. MAY
BEGIN TO SEE SOME WRAP AROUND SHOWERS AROUND THIS SYSTEM AFFECT
PORTIONS OF DEEP E TX/NCNTRL LA AS EARLY AS LATE SUNDAY
NIGHT...INCREASING DURING THE DAY MONDAY AS THE MID/UPPER LEVEL
REFLECTION OF THE CENTER DRIFTS INTO SE LA/SRN MS MONDAY EVENING.
CURRENT MEDIUM RANGE PROGS MAINTAIN THE CENTER OF CIRCULATION TRACKING
NE ALONG THE LS/MS COAST MONDAY NIGHT...WITH THE 850-700MB LOW FARTHER
NW AWAY FROM THE SFC CENTER. THIS WOULD KEEP THE FOCUS FOR HEAVY
RAINFALL ESE OF THE FORECAST AREA MONDAY/MONDAY NIGHT...OVER SE LA/SRN
MS/AL...AS THE REMNANTS OPEN UP AND BEGIN TO ACCELERATE E AWAY FROM
THE REGION TUESDAY AHEAD OF THE TROUGH. GIVEN THE EXACT UNCERTAINTY
OF THE TRACK...HIGH CHANCE POPS WILL REMAIN OVER THE ERN SECTIONS OF
NCNTRL LA...TAPERED OFF FARTHER W AWAY FROM THE CENTER. WILL NOT
INCLUDE HEAVY RAIN MENTION ATTM FOR THE ERN ZONES...ALTHOUGH SHOULD
THIS TRACK VERIFY...CAN/T RULE OUT QPF AMOUNTS OF UP TO 1" MAINLY E OF
A MLU...TO AEX LINE. GIVEN THE LAST 8 DAYS OF DRYING...AND THE MORE
SIGNIFICANT RAINS TO THE E OF THE AREA...NOT EXPECTING THIS RAINFALL
TO AGGRAVATE ONGOING RIVER/LAKE FLOODING ACROSS N LA.
STRONG CANADIAN SFC RIDGING WILL BUILD S INTO THE SRN PLAINS/LOWER MS
VALLEY IN WAKE OF THIS SYSTEM TUESDAY...RESULTING IN A REINFORCEMENT
OF A COOLER/DRY AIR MASS BACK INTO THE AREA. A DRY NW FLOW ALOFT WILL
YIELD THE PLEASANT CONDITIONS THROUGHOUT THE REMAINDER OF THE
WEEK...BEFORE TEMPS BEGIN TO MODERATE AND LOW LEVEL MOISTURE
INCREASES FRIDAY AS SW FLOW COMMENCES AHEAD OF THE NEXT DEEP TROUGH
EXPECTED TO DIG SE ACROSS THE ROCKIES. THIS WILL SEND ANOTHER COLD
FRONT SE...WITH AT LEAST ISOLATED SHOWERS DEVELOPING ALONG/AHEAD OF
THE FRONT NEXT WEEKEND. STILL TOO MUCH UNCERTAINTY B/W THE GFS AND
ECMWF TO WARRANT ANYTHING MORE THAN SLIGHT CHANCE POPS ATTM...ALTHOUGH
THE ECMWF IS MUCH SLOWER/MORE BULLISH WITH RAINFALL THROUGHOUT NEXT
WEEKEND/EARLY NEXT WEEK. WE SHALL SEE.
PRELIMS TO FOLLOW BELOW...
15
AVIATION
AS PLANNED...CLOUDS HAVE CLEARED AND VFR CONDITIONS PREVAIL ACROSS
ALL TERMINAL SITES THIS AFTERNOON. THE TROUBLE IS TONIGHT INTO
TOMORROW MORNING. FEEL LIKE LOW LEVEL INVERSION WILL SET UP ONCE
AGAIN...TRAPPING SHALLOW MOISTURE WHICH WILL COME NORTH AGAIN FROM
THE COAST. HAVE MOST TERMINALS FALLING TO IFR CONDITIONS AFTER
MIDNIGHT WITH LIFR/VLIFR CEILINGS AND VSBYS ACROSS MOST AREAS BY
SUNRISE...CONTINUING THROUGH 15Z OR SO. CEILINGS SHOULD QUICKLY
BECOME MVFR IN THE 16-17Z TIMEFRAME. THE ONLY FLY IN THE OINTMENT SO
TO SPEAK WOULD BE CIRRUS SPREADING OVERHEAD LATE TONIGHT WHICH MAY
TEND TO INHIBIT GOOD FOG FORMATION. FOR NOW...WILL BE PESSIMISTIC
AND GO WITH THE LOWER VIS CATEGORIES AFTER MIDNIGHT. /13/
PRELIMINARY POINT TEMPS/POPS
SHV 54 75 59 71 56 / 0 10 20 40 20
MLU 50 75 58 68 57 / 0 0 30 50 50
DEQ 48 75 54 73 52 / 0 0 10 20 10
TXK 54 74 57 72 54 / 0 0 20 30 20
ELD 49 75 56 70 55 / 0 0 20 40 30
TYR 59 75 58 74 56 / 0 10 20 20 10
GGG 54 75 57 73 56 / 0 10 20 20 10
LFK 56 76 60 74 57 / 0 10 30 30 20
SHV WATCHES/WARNINGS/ADVISORIES
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
15/13
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