Area Forecast Discussion
Issued by NWS Shreveport, LA

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000
FXUS64 KSHV 312154
AFDSHV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
354 PM CST SAT JAN 31 2015

.DISCUSSION...
THE LEADING EDGE OF THE STRATOCU RETURN HAS NOW NUDGED NWD INTO
THE SW AND WRN SECTIONS OF E TX AS OF MID-AFTERNOON...WITH THE
MOISTURE ADVECTION EXPECTED TO INCREASE RAPIDLY THIS EVENING ON A
45-50KT SWRLY LLJ THAT WILL DEVELOP OVER THE SRN PLAINS. THIS WILL
BE IN RESPONSE TO HEIGHT FALL AHEAD OF A DEEPENING UPPER TROUGH
NOW NOSING INTO CNTRL WY PER THE WATER VAPOR LOOP...THAT WILL
AMPLIFY AS IT CROSSES THE CNTRL PLAINS TONIGHT INTO THE SRN
PLAINS/MID MS VALLEY SUNDAY. THE MOSAIC RADAR IMAGERY INDICATES A
LARGE N-S RAIN SHIELD ACROSS CNTRL/NE OK INTO CNTRL TX ALONG THE
I-35 CORRIDOR...WITH A FEW ISOLATED AREAS OF -RA DEVELOPING JUST
NW OF SLR. THE PROGS HAVE SLOWED THE PACE AT WHICH THE -SHRA WILL
MOVE INTO E TX/SE OK...BUT SHOULD ENTER THESE AREAS BY MID TO LATE
EVENING...THUS HAVE TRIMMED BACK THE START TIME OF POPS FARTHER E
ACROSS SCNTRL AR/N LA UNTIL AFTER 06Z...WITH THE -SHRA EXPECTED TO
BECOME MORE WIDESPREAD LATE. BOTH THE GFS AND NAM INDICATE STRONG
LOW LEVEL CONVERGENCE DEVELOPING LATE AHEAD OF A COLD FRONT THAT
WILL EXTEND FROM NE AND SRN OK INTO WCNTRL TX BY 12Z SUNDAY...WITH
SLIGHTLY BETTER ELEVATED LAPSE RATES ADVECTING IN BENEATH THE
UPPER TROUGH. LOW LEVEL AND DEEP LAYER SHEAR HAVE INCREASED FROM
PREVIOUS RUNS AS WELL...THUS HAVE ADDED ISOLATED THUNDER TO THE
FORECAST FOR NE TX/SE OK/SW AR WELL AHEAD OF THE FRONT. QPF
AMOUNTS STILL LOOK TO RANGE FROM 0.25-0.50 INCHES WITH ISOLATED
HIGHER AMOUNTS...COMPARABLY LOWER THAN THE LAST FEW SYSTEMS THAT
HAVE RESULTED 1-3 INCHES EACH EARLIER THIS MONTH. NOT EXPECTING
TEMPS TO FALL MUCH THIS EVENING FROM THE MID-AFTERNOON
READINGS...WITH INCREASING SE WINDS AND LATENT HEAT RELEASE FROM
THE FALLING WATER DROPLETS FROM A WARMER ENVIRONMENT ALOFT EXPECTED
TO CONTRIBUTE TO TEMPS ACTUALLY WARMING LATE.

CONVERGENCE ALONG THE FRONT SHOULD WEAKEN BY LATE MORNING/EARLY
AFTERNOON SUNDAY AS THE FRONT ENTERS NE TX/SW AR...WITH A LITTLE
BETTER SFC/MLCAPES /AROUND 500 J/KG/ DEVELOPING AHEAD OF THE FRONT
ACROSS THE EXPANDING WARM SECTOR. THIS SHOULD ALSO SUPPORT THE
MENTION OF ISOLATED THUNDER AS WELL AREAWIDE...WITH THE CONVECTION
EXPECTING TO DIMINISH FROM W TO E DURING THE AFTERNOON/WITH THE
COLD FROPA. PREFER THE SLIGHTLY SLOWER FROPA MOVEMENT THAT THE NAM
IS ADVERTISING AS THIS FRONT SHOULD BE SHALLOW AT FIRST...AND MAY
STRUGGLE OVERCOMING THE HIGHER TERRAIN OF THE OUACHITAS OVER SE
OK/WRN AR. HOWEVER...TEMPS AND DEWPOINTS SHOULD QUICKLY FALL
BEHIND THE FRONT...WITH THE PRESSURE GRADIENT TIGHTENING BY SUNDAY
NIGHT SUCH THAT PORTIONS OF E TX/SE OK/ADJACENT SW AR WILL BE NEAR
LAKE WIND ADVISORY CRITERIA BEFORE THE GRADIENT RELAXES BY
DAYBREAK MONDAY.

CANADIAN SFC RIDGING WILL SETTLE IN ACROSS THE MID MS VALLEY/SRN
PLAINS MONDAY...RESULTING IN MUCH BELOW NORMAL TEMPS AREAWIDE AS
THEY STRUGGLE TO REACH THE MID/UPPER 40S. SHOULD SEE A FREEZE
AREAWIDE MONDAY NIGHT BEFORE A RETURN SRLY FLOW RESULTS IN TEMPS
MODERATING BACK TO NEAR SEASONAL NORMS TUESDAY. THE CLOSED LOW
WHICH WILL SHUNT THE BULK OF THE PACIFIC MOISTURE E ACROSS THE
REGION OVER THE NEXT 24 HOURS...CONTINUES TO DROPS S INTO NRN
BAJA/NW MX THIS AFTERNOON...AND WILL BE A PLAYER IN OUR WEATHER BY
MIDWEEK AS IT CROSSES INTO NCNTRL OLD MX TUESDAY AND INTO S TX
WEDNESDAY MORNING. BOTH THE GFS/ECMWF HAVE SHIFTED A LITTLE
FARTHER S AND SLOWER WITH THE LOW TRACK THAN 24 HOURS AGO...WITH
THE PROGS CONTINUING TO BRING SOME LIGHT QPF INTO E TX/N LA
TUESDAY NIGHT/WEDNESDAY. GIVEN THE MODEL CONSENSUS /INCLUDING THE
CANADIAN/...HAVE RAISED POPS TO MID AND HIGH CHANCE FOR THE SRN
ZONES TUESDAY NIGHT AND WEDNESDAY...WITH ANOTHER SHORTWAVE
DEVELOPING IN THE NW FLOW ALOFT EXPECTED TO SHIFT ANOTHER COLD
FRONT BACK SE INTO THE REGION THURSDAY. THE GFS IS COLDER WITH THE
FROPA GIVEN ITS AMPLIFICATION OF THIS NEXT SHORTWAVE THAN THE
ECMWF...AND IS CONSISTENT WITH THE CANADIAN SOLUTION AS
WELL...WHICH COULD RESULT IN AT LEAST ISOLATED AREAS OF COLD -RA
DEVELOPING AREAWIDE THURSDAY NEAR/BEHIND THE FRONT.

TEMPS SHOULD TREND BACK TO NEAR SEASONAL NORMS BY FRIDAY...WITH
EVEN MILDER AND DRY CONDITIONS EXPECTED NEAT WEEKEND IN TIME FOR
THE MARDI GRAS PARADES SCHEDULED TO RESUME ACROSS THE REGION.

PRELIMS TO FOLLOW BELOW...

&&

.PREV DISCUSSION... /ISSUED 1240 PM CST SAT JAN 31 2015/

AVIATION...
VFR CONDITIONS ACROSS AREA WITH MAINLY JUST MID/UPPER LVL CLOUDS
TO LIKELY PREVAIL THRU AT LEAST 01/00Z...WHEN CLOUD BASES BEGIN TO
LOWER OVER NE TX. PATCHY RAIN DURING THE EVENING WILL BECOME MORE
WIDESPREAD OVERNIGHT...WITH CIGS BECMG LOW MVFR AND OCNL IFR.
E-SE WINDS 5 TO 10 KTS THIS AFTN TO BECOME SOUTHERLY AND INCREASE
TO 10 TO 15 KTS OVERNIGHT...WITH HIGHER GUSTS POSSIBLE OVER NE
TX/SE OK. A COLD FRONT MOVING INTO AREA DURING DAYTIME SUNDAY WILL
BRING CHANCE OF A FEW TSTMS...MAINLY SOUTH OF I-20...BEFORE
RAINFALL ENDS AND CIGS BEGIN TO IMPROVE LATER IN DAY. /VII/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  54  63  31  47  28 /  70  90  10   0   0
MLU  49  65  34  45  26 /  60 100  30   0   0
DEQ  48  56  25  43  25 / 100  90  10   0   0
TXK  51  60  28  43  26 /  90 100  10   0   0
ELD  49  61  31  44  24 /  80 100  20   0   0
TYR  55  60  28  46  30 /  90  80  10   0   0
GGG  54  62  29  46  28 /  90  90  10   0   0
LFK  56  68  34  49  28 /  70  80  20   0   0

&&

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

$$

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