300
FXUS64 KSHV 170331
AFDSHV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
1031 PM CDT SUN JUN 16 2019
UPDATE
AS GENERALLY EXPECTED, THE PRIOR SEMI-ORGANIZED CONVECTIVE COMPLEX
COMING INTO WESTERN PORTIONS OF THE FOUR STATE REGION EARLY THIS
EVENING DID QUICKLY WEAKEN AND FALL-APART OVER THE LAST FEW HOURS.
THERE IS STILL SOME SHOWERS AND EMBEDDED THUNDERSTORMS ASSOCIATED
WITH THIS ACTIVITY LINGERING IN WESTERN AND SOUTHERN PORTIONS OF
THE FORECAST AREAS, BUT THERE ARE LARGE PORTIONS OF THE NORTHERN
AND EASTERN SECTIONS OF THE REGION THAT ARE PREDOMINATELY DRY AT
THIS HOUR.
FOR THE REMAINDER OF THE NIGHT, DESPITE MENTIONED RECENT TRENDS,
THE FACT THAT THE BOTTOM-END OF A SEASONALLY SIGNIFICANT UPPER
SHORTWAVE IS MOVING INTO THE REGION MEANS THERE WILL LIKELY BE
SOME SCATTERED PRECIPITATION PERSISTING OVER THE REGION
INTERMITTENTLY THROUGH THE NIGHT. 850 MB THETA-E ADVECTION AND
MOISTURE CONVERGENCE WEST DOWN THE I-20 CORRIDOR TO DALLAS IS
SPURRING ELEVATED THUNDERSTORM PRODUCTION CURRENTLY (THAT IS
HAVING A TOUGH TIME MAKING INROADS INTO OUR FORECAST AREA). I
ANTICIPATE AT LEAST SOME ACTIVITY WILL EVENTUALLY HAVE BETTER
SUCCESS TAKING A FOOTHOLD IN AT LEAST THE NORTHERN HALF OF THE CWA
LATER TONIGHT, ALTHOUGH THE PROSPECT FOR ANY HAZARDOUS WEATHER
THREAT MORE THAN LOCALLY HEAVY RAINFALL OR LIGHTNING IS ON THE LOW
SIDE. TEMPERATURES ARE RUNNING MAINLY IN THE 65 TO 70 DEGREE RANGE
AT THIS HOUR AND WILL LIKELY NOT MOVE MUCH THROUGH THE REMAINDER
OF THE NIGHT. WET GROUND AND A MOIST BOUNDARY LAYER WILL YIELD
SOME POTENTIAL FOR FOG IF SKIES CAN CLEAR OUT A BIT, BUT AT THIS
POINT SUFFICIENT CLEARING FOR MUCH DENSE FOG IS NOT EXPECTED. /50/
PREV DISCUSSION
/ISSUED 733 PM CDT SUN JUN 16 2019/
UPDATE...
COMPLEX WEATHER SITUATION THIS AFTERNOON INTO THIS EVENING AND
AVAILABLE HI RESOLUTION MODEL GUIDANCE HAS NOT BEEN MUCH HELP IN
FIGURING OUT DETAILS (AS THIS GUIDANCE HAS BEEN PLAYING CATCH-UP
ALL DAY). INITIAL CONVECTION COMING INTO THE FOUR STATE REGION
THIS MORNING MADE MORE HEADWAY THROUGH THE REGION THAN ANTICIPATED
AND NOW LOW TO MID LAYER BAROCLINICITY IN THE WAKE OF THE
PREVIOUS (BUT NOW DECAYING) COMPLEX IS HELPING DRIVING MOVEMENT OF
ANOTHER THUNDERSTORM COMPLEX INTO THE ARKLATEX AND EAST TEXAS.
REMAINING INSTABILITY PRECEDING THE COMPLEX COMING IN IS NOT
EXPECTED TO BE ENOUGH TO SUSTAIN SEVERE CONVECTION, EVEN
CONSIDERING ATYPICAL LEVELS OF SYNOPTIC LIFT AND WIND SHEAR
AVAILABLE. SO, FOR NOW, WE ANTICIPATE A SUB-SEVERE THUNDERSTORM
COMPLEX TO COME INTO THE REGION FOR TONIGHT WITH SOME UNCERTAINTY
ON HOW FAR IT WILL GET BEFORE TOTALLY DISSIPATING. THE MAIN
HAZARDOUS WEATHER CONCERN TONIGHT WILL BE FROM HEAVY RAINFALL IN
AREAS THAT ALREADY RECEIVED DOWNPOURS THROUGHOUT THE DAY,
ESPECIALLY IF COMPLEX CAN MAINTAIN VIGOR FOR SEVERAL MORE HOURS.
/50/
AVIATION...
MVFR FLIGHT CATS DUE TO A COMBINATION OF CEILINGS AND
THUNDERSTORMS IS POPPING UP IN PATCHY FASHION IN THE ARKLATEX AND
EAST TEXAS, ALTHOUGH MOST TAF SITES ARE STILL VFR. EXPECTING
PATCHY MVFR TO BE POSSIBLE THROUGHOUT THE NIGHT DUE TO MIGRATING
SHOWER AND EMBEDDED THUNDERSTORM COMPLEX. LATE TONIGHT THERE IS
ALSO SOME POTENTIAL FOR IFR CEILINGS AND VISIBILITIES, ESPECIALLY
AT LFK, BUT SOME OF THAT WILL DEPEND ON HOW QUICKLY EVENING
PRECIPITATION CLEARS OUT LATE TONIGHT. TOMORROW, ANTICIPATE A
TRANSITION TO MAINLY VFR CONDITIONS BY MID MORNING WITH SOUTH TO
SOUTHWEST SURFACE WINDS RANGING FROM 5 TO 15 MPH. ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP
THROUGHOUT THE AREA BY MIDDAY TOMORROW AND THE POTENTIAL FOR THIS
IS REPRESENTED IN THE TAFS BY VCTS WORDING. OTHERWISE, EXPECT
WINDS TO BE A BIT ERRATIC TONIGHT DUE TO VARYING PRESSURE
GRADIENTS AROUND THE MENTIONED THUNDERSTORM COMPLEX. /50/
PREV DISCUSSION... /ISSUED 329 PM CDT SUN JUN 16 2019/
SHORT TERM.../TONIGHT THROUGH MONDAY NIGHT/
SHORT RANGE GUIDANCE HAS STRUGGLED TO KEEP UP WITH THE CONVECTION
THAT IS ONGOING. HAVE DECIDED TO GO WITH THE GFS, AT LEAST FOR THE
NEXT 12 TO 24 HOURS, SINCE IT HAS A BETTER HANDLE WITH THE MCS
THAT HAS MOVED THROUGH AND THE CONVECTION THAT IS CURRENTLY OVER
NORTH TEXAS. THUS, PRECIPITATION CHANCES RANGE FROM CHANCE TO
LIKELY OVER THAT TIMEFRAME. PRECIPITABLE WATER ON THIS MORNING'S
SOUNDING WAS 1.60 INCHES FOR TODAY. THIS COUPLED WITH NEARLY
UNIDIRECTIONAL FLOW IS MAKING THESE STORMS EFFICIENT RAIN
PRODUCERS FOR THIS TIME OF YEAR. WHILE THERE IS AN ISOLATED CHANCE
FOR SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING, THE GREATEST
THREAT IN THE SHORT TERM WILL BE HEAVY RAINFALL WITH ISOLATED
FLASH FLOODING POSSIBLE THROUGH MONDAY AFTERNOON. BY MONDAY
EVENING, PRECIPITATION CHANCES SHOULD BE ON THE DECLINE AS THE
WEAK UPPER LEVEL TROUGH SHIFTS EAST OF THE AREA.
HAVE KEPT MAX TEMPERATURES TOMORROW BELOW NORMAL WITH THE AMOUNT
OF CLOUD COVER AND RAIN EXPECTED WHILE LOW TEMPERATURES IN BOTH
PERIODS SHOULD BE NEAR NORMAL. /35/
LONG TERM.../TUESDAY THROUGH SUNDAY/
CONTINUED STG INSTABILITY BUT WITH GREATER UNCERTAINTY OF MOISTURE
AND SHEAR RESULTING IN UNCERTAIN TSTM POTENTIAL TUESDAY AND
WEDNESDAY, ALTHOUGH LOW LVL WINDS BEGIN TO SWITCH FROM THE WEST BACK
TO THE SOUTH DURG THE DAY TUESDAY. WILL KEEP POPS MAINLY LOW END
CHANCE CATEGORY UNDER THESE CIRCUMSTANCES WITH TEMPS WARMING BACK TO
EITHER SIDE OF 90 DEGREES. ECMWF IS MOST EVIDENT WITH SHOWING
CONVECTION ERUPTING OVER NW PORTIONS OF CWA. THE NEXT SHORTWAVE
DEVELOPS WITHIN THE FLOW OVER OK INTO THE MIDDLE RED RIVER VALLEY
WEDNESDAY EVENING. REASONABLE AGREEMENT EXISTS THIS MORNING BETWEEN
THE GFS AND ECMWF WITH A 30-40+ KT SWRLY LLJ FEEDING INTO THIS NEXT
SHORTWAVE TROUGH WEDNESDAY NIGHT, WITH LARGE SCALE FORCING RESULTING
IN ANOTHER POTENTIAL MCS OVER SE OK/SW AR. WILL INCREASE POPS TO
HIGH END CHANCE WED NIGHT INTO THUR WITH ADEQUATE MOISTURE AND
COOLING MID LVLS WITH EXTREME INSTABILITY WITH WED NIGHT MCS
POSSIBLY DEVELOPING IN CLOSE PROXIMITY TO CWA.
RIDGING ALOFT WILL BUILD N FROM CNTRL TX TOWARDS THE AREA INTO THE
WKND WITH ISOLD POPS AND EVEN WARMER TEMPS INTO LOWER TO MIDDLE 90S
EXPECTED. /07/
PRELIMINARY POINT TEMPS/POPS
SHV 68 87 72 89 / 60 60 40 40
MLU 69 87 72 89 / 30 70 50 50
DEQ 67 83 68 87 / 80 50 30 40
TXK 66 85 70 87 / 70 60 40 50
ELD 67 86 70 87 / 40 60 50 50
TYR 67 87 72 88 / 80 50 30 30
GGG 68 87 72 89 / 80 50 40 40
LFK 66 88 73 91 / 80 60 20 30
SHV WATCHES/WARNINGS/ADVISORIES
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
50/07/35
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