375
FXUS64 KSHV 280502
AFDSHV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
1102 PM CST SAT FEB 27 2021
AVIATION
FOR THE ARKLATEX TERMINALS THE WARM FRONT IS EDGING PAST
KTXK/KELD WITH BETTER VSBY AND INCREASING S WIND. ALOFT, WE ARE
S/SE 20-30KT AT 1-2KFT UP. SO THIS LIFR MAY BREAK FOR A SHORT
WHILE THIS EVENING. HOWEVER, MORE MAY DVLP OVERNIGHT AREA WIDE.
LOWERING CIGS AND NOT SO MUCH VSBY ISSUES ON THIS SIDE OF THE WARM
FRONT WITH DVLPG SHWRS/TS SUNDAY LATE AHEAD OF OUR NEXT COLD
FRONT ARRIVING LATE ON SUNDAY AFTN/EVE. SFC WINDS SHIFT TO N, BUT
SW ALOFT KEEPS WITH RAIN INTO MON/TUES. /24/
PREV DISCUSSION
/ISSUED 944 PM CST SAT FEB 27 2021/
UPDATE...
ADDED DENSE FOG ADVISORY TO THE OVERNIGHT AND LOWERED TEMPS NORTH.
SHORT TERM...
IT HAS BEEN SOLID WITH DENSE FOG OF 1/4 TO 1/2 MILE SINCE SUNSET
FROM IDABEL TO EL DORADO, BUT IT APPEARS WE ARE ON THE FRINGE WITH
GROUND FOG PERHAPS NOW LIFTING A BIT. WE WILL CONTINUE MONITOR
FOR IMPROVEMENT, BUT LAST TO GO WILL BE THE VALLEYS AS THIS WARM
FRONT EDGES NORTHWARD. SO ANOTHER UPDATE TO REMOVE SOME OF THIS
ADVISORY HAS A LITTLE MORE OPTIMISM NOW, BUT THE FRONTAL BOUNDARY
DID LOSE SOME GROUND LAST NIGHT SO POTENTIAL GOOD NEWS ONLY IF
THE WARMER AIR CONTINUES TO ARRIVE. OTHERWISE HRRR SHOWING SOME
DEVELOPMENT OF RAIN SHOWERS MAINLY ALONG AND NORTH OF I-30
OVERNIGHT, SPREADING DOWN INTO THE I-20 CORRIDOR EARLY TOMORROW.
/24/
PREV DISCUSSION... /ISSUED 328 PM CST SAT FEB 27 2021/
SHORT TERM.../TONIGHT THROUGH SUNDAY NIGHT/
THE AFOREMENTIONED WARM FRONT, CURRENTLY LOCATED JUST NORTH OF
THE INTERSTATE 20 CORRIDOR, WILL CONTINUE TO PUSH NORTHWARD
THROUGH THE EVENING HOURS OUT OF THE REGION. EARLIER CONVECTION
THAT DEVELOPED NORTH OF THE FRONT HAS RAPIDLY MOVE NORTHWARD
TODAY, AND IS ALMOST OUT OF THE REGION. CAN'T RULE OUT SOME
ADDITIONAL CONVECTION GETTING INTO OUR EXTREME NW ZONES, AS
DEVELOPING ISOLATED SHOWERS/T-STORMS SHIFT NORTHEASTWARD OUT OF
NORTH TEXAS. ELSEWHERE ACROSS THE REGION, TEMPERATURES HAVE WARMED
INTO THE 70S IN WAKE OF THE FRONTAL BOUNDARY. THERE HAS EVEN BEEN
A FEW BREAKS IN CLOUD COVER. A FEW WARM AIR ADVECTION SHOWERS
HAVE DEVELOPED ACROSS OUR CENTRAL AND NORTHEAST LOUISIANA
PARISHES, BUT THIS ACTIVITY SHOULD DIMINISH BY SUNSET. EXPECT LOW
CLOUDS TO RETURN OVERNIGHT WITH WARMER TEMPERATURES AREAWIDE, AS
OVERNIGHT LOWS WILL RANGE FROM THE UPPER 50S NORTH, TO MID 60S
ACROSS OUR SOUTHERN ZONES.
BY SUNDAY, A LONGWAVE TROUGH WILL DIVE SE THROUGH THE ROCKIES AND
INTO THE FOUR CORNERS REGION ON SUNDAY, BEFORE EVENTUALLY CLOSING
OFF SUNDAY NIGHT OVER SOUTHERN NEW MEXICO. THE WILL ALLOW FOR DEEP
SW FLOW ALOFT TO REMAIN OVER THE REGION THROUGH EARLY NEXT WEEK. AT
THE SAME TIME, A COLD FRONT WILL DRIFT SE INTO THE REGION BY MIDDAY
SUNDAY/SUNDAY AFTERNOON AND SLOWLY PUSH THROUGH THE REGION BY EARLY
MONDAY MORNING BRINGING WIDESPREAD CONVECTION TO THE REGION.
ALTHOUGH SFC INSTABILITY IS MARGINAL WITH THIS SYSTEM, EFFECTIVE
BULK SHEAR IS OVER 50 KTS AND THERE COULD BE JUST ENOUGH ELEVATED
INSTABILITY AND DECENT MID-LEVEL LAPSE RATES FOR SOME HAIL AND
HIGH WINDS WITH ELEVATED CONVECTION. THERE IS ALSO THE POTENTIAL
FOR ADDITIONAL HEAVY RAINS TO FALL ACROSS THE REGION. WITH ALREADY
SATURATED AREAS OF NE TX/SW AR FROM PREVIOUS RAINFALL THIS PAST
WEEK, MINOR FLOODING OF LOW LYING AND POOR DRAINAGE AREAS WILL BE
POSSIBLE. AS OF NOW, MODELS SUGGEST QPF WILL BE JUST BELOW FLASH
FLOOD GUIDANCE, SO WILL HOLD OFF ON ANY FLOOD WATCHES AT THIS
TIME. WARM AND HUMID CONDITIONS ARE EXPECTED ON SUNDAY AHEAD OF
THE FRONT, WITH TEMPS IN THE 70S AREAWIDE. COOLER CONDITIONS
EXPECTED BY MONDAY MORNING IN WAKE OF THE FRONT, WITH POST
FRONTAL PRECIP EXPECTED ACROSS THE REGION. /20/
LONG TERM.../MONDAY THROUGH SATURDAY/
BY MONDAY MORNING, THE COLD FRONT SHOULD BE EXITING THE REGION INTO
SE TX/CNTRL LA, ALTHOUGH DEEP SW FLOW ATOP THE SHALLOW POST-FRONTAL
AIR MASS WILL CONTINUE, AHEAD OF A CLOSED LOW THAT WILL ENTER NW TX.
ELEVATED ISENTROPIC FORCING IS EXPECTED TO CONTINUE AHEAD OF THIS
LOW MONDAY, THUS CONTINUING THE POST-FRONTAL RAINS OVER MUCH OF THE
REGION EVEN AS THE LOW BEGINS TO OPEN UP INTO A MORE PROGRESSIVE
WAVE UPON ENTERING OK. HAVE MAINTAINED LIKELY AND CATEGORICAL POPS
OVER MUCH OF THE AREA MONDAY AND MONDAY NIGHT, WITH LARGE SCALE
ASCENT INCREASING JUST AHEAD OF THE TROUGH MONDAY NIGHT. DID TAPER
BACK MAX TEMPS MONDAY AFTERNOON FROM THE MILDER NBM MAINLY ALONG/S
OF THE I-20 CORRIDOR GIVEN THE PERSISTENT RAINS AND WEAK COLD
ADVECTION, WHILE ALSO TRENDING MAX TEMPS TUESDAY A BIT COOLER AS
WELL TO DEPICT THE SLOWER MOVEMENT OF THE LOW FROM THE
ECMWF/CANADIAN THAN THE MORE PROGRESSIVE GFS, WHICH SEEMS MORE
LIKELY GIVEN THE INITIAL CLOSED SOLUTION AS IT DRIFTS E ACROSS OK/N
TX.
DRIER AIR ALOFT WILL QUICKLY ENTRAIN E BENEATH THE DEPARTING TROUGH
TUESDAY AFTERNOON, WITH SFC RIDGING OVER THE OZARKS INTO ECNTRL TX
BUILDING S INTO THE REGION. THIS SHOULD SET THE STAGE FOR GOOD
RADIATIONAL COOLING WEDNESDAY NIGHT (ASSUMING ANY LINGERING STRATUS
NEAR AND E OF THE MS RIVER DOESN'T ADVECT BACK WSW INTO THE AREA),
RESULTING IN WHAT SHOULD BE THE COOLEST TEMPS EXPECTED THROUGH THE
FORECAST PERIOD AS MIN TEMPS FALL INTO THE 30S TO NEAR 40 DEGREES.
THIS RIDGING WILL WEAKEN AS IT DRIFTS OFF TO THE E THURSDAY, AS WE
AWAIT THE APPROACH OF ANOTHER CLOSED LOW THAT WILL SHIFT E INTO THE
SRN PLAINS LATE THURSDAY. A SW FLOW ALOFT WILL AGAIN DEVELOP AHEAD
OF THIS APPROACHING LOW, WITH A GRADUAL INCREASE IN LARGE SCALE
FORCING RESULTING IN THE DEVELOPMENT OF ELEVATED SHRA, WHICH WOULD
HAVE TO SATURATE THE AIR MASS FROM THE TOP DOWN, GIVEN THE WEAK LOW
LEVEL MOISTURE ADVECTION EXPECTED TO BE IN PLACE. HAVE GRADUALLY
STEPPED UP THE POPS FOR THE THURSDAY TIMEFRAME, WITH CHANCE POPS
RETURNING THURSDAY AFTERNOON AND ESPECIALLY THURSDAY NIGHT. AGAIN
PREFER THE SLOWER ECMWF/CANADIAN CONSENSUS THAN THE MORE PROGRESSIVE
GFS, WHICH CLEARS THE RAINS OUT ABOUT 12HRS FASTER. THUS, HAVE
MAINTAINED CHANCE POPS INTO MUCH OF FRIDAY, BEFORE DRIER AIR AND
INCREASING SUBSIDENCE TAPER THE RAINS IN WAKE OF THE ATTENDANT COLD
FRONT THAT ENTERS THE REGION LATE IN THE DAY. THIS FRONT LOOKS TO
HAVE LITTLE SENSIBLE EFFECT ON TEMPS FOR LATE WEEK INTO NEXT
WEEKEND, WITH READINGS NEAR THE SEASONABLE NORMS. /15/
PRELIMINARY POINT TEMPS/POPS
SHV 66 77 51 54 / 10 60 90 80
MLU 68 78 52 55 / 10 40 90 80
DEQ 54 72 44 56 / 40 90 70 30
TXK 59 74 47 53 / 30 90 90 50
ELD 60 76 45 53 / 20 80 90 70
TYR 66 74 49 53 / 10 80 90 80
GGG 65 76 49 54 / 10 80 90 80
LFK 66 78 56 60 / 10 40 90 90
SHV WATCHES/WARNINGS/ADVISORIES
AR...DENSE FOG ADVISORY UNTIL 9 AM CST SUNDAY FOR ARZ050-051-059>061-
070>073.
LA...NONE.
OK...DENSE FOG ADVISORY UNTIL 9 AM CST SUNDAY FOR OKZ077.
TX...DENSE FOG ADVISORY UNTIL 9 AM CST SUNDAY FOR TXZ096-097.
24/20/15
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