860
FXUS64 KEWX 141150
AFDEWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
650 AM CDT FRI MAY 14 2021
UPDATE
PLEASE SEE THE 12Z AVIATION FORECAST DISCUSSION BELOW.
AVIATION
LOW CLOUDS CONTINUE THIS MORNING, BUT BASES HAVE YET TO LOWER INTO
MVFR ALONG THE I-35 CORRIDOR. BASED ON THE LATEST GUIDANCE, WE WILL
ONLY MENTION A TEMPO GROUP FOR SAT BETWEEN 14-16Z THIS MORNING.
OTHERWISE, EXPECT VFR CONDITIONS ALONG I-35 THROUGH THIS EVENING. LOW
CLOUDS SHOULD RETURN QUICKLY ALONG I-35 AFTER 15/04Z. AT DRT, MVFR
CLOUDS ARE INTACT AND WILL CONTINUE THROUGH EARLY AFTERNOON.
IMPROVEMENT BACK TO VFR IS EXPECTED AFTER 18Z, WITH LOW CLOUDS
RETURNING AROUND 15/07Z. WE COULD ALSO SEE SOME CONVECTION DEVELOP
ACROSS THE RIO GRANDE PLAINS EARLY SATURDAY MORNING, WITH THE BEST
CHANCE EXPECTED JUST BEYOND THE END OF THE CURRENT TAF PERIOD AT DRT.
PREV DISCUSSION
/ISSUED 337 AM CDT FRI MAY 14 2021/
SHORT TERM (TODAY THROUGH SATURDAY)...
EARLY MORNING SATELLITE IMAGERY AND SURFACE OBSERVATIONS SHOW LOW
CLOUDS ARE IN PLACE ACROSS A GOOD PORTION OF SOUTH CENTRAL TEXAS.
TEMPERATURES CURRENTLY RANGE FROM THE MID 50S IN THE HILL COUNTRY TO
NEAR 70 DEGREES ACROSS THE COASTAL PLAINS AND ALONG THE RIO GRANDE.
CLOUDS WILL REMAIN FAIRLY THICK THROUGH THE MORNING HOURS, WITH SOME
DECREASE IN COVERAGE EXPECTED LATE IN THE AFTERNOON. WITH COOL
TEMPERATURES ALREADY IN PLACE AND CLOUDS KEEPING A LIMIT ON
INSOLATION, AFTERNOON HIGHS WILL BE BELOW NORMAL, WITH UPPER 70S TO
MID 80S IN STORE. WE WILL KEEP THE FORECAST DRY FOR TODAY, BUT WILL
CONTINUE TO MENTION A LOW CHANCE FOR SHOWERS AND THUNDERSTORMS ALONG
THE RIO GRANDE AFTER MIDNIGHT. SOME WEAK UPPER LEVEL DISTURBANCES
MOVING IN FROM THE WEST COMBINED WITH GULF MOISTURE SHOULD ALLOW
SOME CONVECTION TO DEVELOP EARLY SATURDAY MORNING ALONG THE RIO
GRANDE.
RAIN CHANCES INCREASE SIGNIFICANTLY ALONG THE RIO GRANDE SATURDAY
MORNING, THEN SPREAD EAST ACROSS THE REMAINDER OF THE REGION
SATURDAY AFTERNOON. A STRONG STORM OR TWO COULD BE POSSIBLE SATURDAY
AFTERNOON ALONG AND WEST OF AN EAGLE PASS TO ROCKSPRINGS LINE.
MARGINALLY SEVERE HAIL AND STRONG WIND GUSTS ARE THE MAIN SEVERE
WEATHER CONCERNS. THE LATEST WPC EXCESSIVE RAINFALL OUTLOOK ALSO
BRINGS A MARGINAL RISK FOR LOCALLY HEAVY RAINFALL TO AREAS GENERALLY
ALONG AND WEST OF U.S. HIGHWAY 281. AT THIS TIME, MODEL
PRECIPITATION ESTIMATES ARE NOT VERY HIGH. HOWEVER, RAINFALL RATES
IN THE STRONGER CONVECTION COULD BRING A LOCALIZED CONCERN FOR
BRIEF, HEAVY DOWNPOURS.
LONG TERM (SATURDAY NIGHT THROUGH THURSDAY)...
THUNDERSTORMS WILL BE ONGOING OUT OVER THE SOUTHERN EDWARDS PLATEAU
AND RIO GRANDE PLAINS AT THE START OF THE PERIOD, WITH ORGANIZATION
INTO AN MCS POSSIBLE BY EARLY SUNDAY MORNING. THE LAST FEW RUNS OF
THE NAM CONTINUE TO INDICATE THIS SCENARIO UNFOLDING, WITH SOME
AGREEMENT FROM GLOBAL MODELS AS WELL. HOW THINGS EVOLVE LATER ON
SUNDAY IS MORE UNCERTAIN. WITH THE POSSIBILITY OF AN ONGOING MCS
ADVANCING EASTWARD PAST THE HIGHWAY 281 CORRIDOR BY SUNRISE, AND
PUSHING INTO THE COASTAL PLAINS BY MID-MORNING, ATMOSPHERIC RECOVERY
INTO THE AFTERNOON WILL BE THE PRIMARY QUESTION. WILL OUR WESTERN
COUNTIES HAVE ENOUGH TIME TO RELOAD FOR THE POSSIBILITY OF
THUNDERSTORM DEVELOPMENT BY THE LATE AFTERNOON/EARLY EVENING ON
SUNDAY? A MID TO UPPER LEVEL SHORTWAVE WILL SLIDE EASTWARD THROUGH
THE HILL COUNTRY BY LATE SATURDAY AND EARLY SUNDAY, HELPING TO
INCREASE THE SYNOPTIC FORCING FOR ASCENT OVER THE REGION. AT THIS
TIME, CONDITIONS APPEAR FAVORABLE FOR STORMS TO DEVELOP OUT WEST,
WITH DEEP LAYER SHEAR OF 40-50 KTS, STEEP MID-LEVEL LAPSE RATES OF
7-7.5 C/KM, AND AMPLE MUCAPE OF 2500-3500 J/KG GENERALLY WEST OF
HIGHWAY 83. IF SKIES CAN CLEAR IN TIME, AND TEMPERATURES CAN RECOVER,
DESTABILIZATION IS POSSIBLE, AND AS A RESULT, SPC HAS INTRODUCED A
MARGINAL RISK (LEVEL 1 OF 5) FOR AREAS ALONG AND WEST OF AN EAGLE
PASS TO LEAKEY TO JUNCTION LINE. THE PRIMARY HAZARD WITH ANY STORMS
THAT FORM WILL BE LARGE HAIL.
TURNING OUR ATTENTION TO THE NEXT THREAT, MONDAY THROUGH WEDNESDAY
LOOKS TO BE A RATHER ACTIVE PERIOD FOR SOUTH-CENTRAL TEXAS WITH
MULTIPLE ROUNDS OF RAIN AND THUNDERSTORMS, SOME OF WHICH COULD BE
STRONG TO SEVERE. A POWERFUL H5 LOW WILL MOVE OVER THE FOUR CORNERS
LATE MONDAY, HELPING TO INCREASE FORCING FOR ASCENT OVER THE REGION.
ALL THREE GLOBAL MODELS ARE IN GOOD AGREEMENT ON THE PLACEMENT AND
TIMING OF THIS UPPER LEVEL TROUGH/LOW THROUGH MONDAY EVENING, BEFORE
DIVERGING TUESDAY MORNING. WHILE THE CANADIAN/ECMWF DEPICT A SLIGHTLY
WEAKER, MORE ELONGATED UPPER LOW OVER NORTHEASTERN COLORADO BY
WEDNESDAY MORNING, THE GFS REMAINS THE STRONGER OF THE SOLUTIONS AND
THE FURTHEST SOUTH, CENTERED OVER THE TEXAS PANHANDLE. ULTIMATELY,
HOW THE OVERALL CONVECTIVE PATTERN EVOLVES IS HIGHLY DEPENDENT ON
THE PLACEMENT OF THIS UPPER LEVEL LOW AND HOW IT IS ORIENTED. ONE
THING ALL THREE MEMBERS HAVE IN COMMON IS A NEGATIVELY TILTED TROUGH
BY LATE TUESDAY AND STRETCHING INTO WEDNESDAY. THIS WILL ENHANCE LIFT
AND WAA OVER THE WARM SECTOR ON BOTH TUESDAY AND WEDNESDAY
AFTERNOONS.
AT THIS TIME, THE FEELING IS THAT SOME STRONG TO SEVERE STORMS WILL
BE POSSIBLE MONDAY-WEDNESDAY, BUT WHERE AND EXACTLY WHEN IS MORE UP
IN THE AIR THAN ANYTHING ELSE. THE DRYLINE WILL LIKELY REMAIN OUT
WEST, ALLOWING QUITE A BIT OF MOISTURE TO SURGE WEST AND NORTH OVER
THE CWA ALL THREE DAYS. ONE THING THAT COULD LIMIT SEVERE POTENTIAL
IS THE EXTENSIVE CLOUD COVER EXPECTED OVER THE REGION WHICH COULD
LIMIT SURFACE HEATING. HOWEVER, GIVEN SUBSTANTIAL MUCAPE OF 2000-3000
J/KG, STEEP MID-LEVEL LAPSE RATES OF 7.5-8.5 C/KM, AND VEERING
PROFILES, ALL MODES OF SEVERE WEATHER ARE POSSIBLE, ESPECIALLY LARGE
HAIL, IF THE CAP CAN BE BROKEN EACH AFTERNOON.
WITH REGARD TO THE THREAT FOR FLOODING, IT'S BECOMING AN INCREASINGLY
BIGGER CONCERN AS FREEZING LEVELS WILL REMAIN QUITE HIGH, LEADING TO
VERY EFFICIENT WARM RAIN PROCESSES. ADDITIONALLY, PRECIPITABLE WATER
IS RUNNING SOME +2 STANDARD DEVIATIONS ABOUT THE MEAN, AND AROUND
150% OF NORMAL FOR MID-MAY. PWATS OF 1.5-2" WILL BE COMMON SUNDAY-
WEDNESDAY, AS THE GULF OF MEXICO REMAINS WIDE OPEN FOR BUSINESS.
FURTHERMORE, MODEL SOUNDINGS INDICATE LONG, SKINNY CAPE AND A NEARLY
SATURATED VERTICAL COLUMN, WHICH IS A TELLTALE SIGN OF HEAVY RAIN
POTENTIAL. ADD THIS TO THE ALREADY SATURATED SOILS AROUND THE AREA,
AND FLASH FLOODING POTENTIAL LOOKS TO BE GREATEST LATE TUESDAY
THROUGH WEDNESDAY, ESPECIALLY ACROSS THE I-35 CORRIDOR AND POINTS
EASTWARD. AT THIS TIME, WPC HAS PORTIONS OF THE HILL COUNTRY AND
COASTAL PLAINS WITHIN A DAY 2 AND DAY 3 MARGINAL RISK FOR FLOODING
RAIN. WIDESPREAD RAINFALL TOTALS OF 2-4" ARE POSSIBLE WITH LOCALLY
HEAVIER AMOUNTS IN EXCESS OF 5" BY THURSDAY MORNING.
BEYOND WEDNESDAY, MODELS DIVERGE SUBSTANTIALLY, AND HOW THE OVERALL
SYNOPTIC PATTERN EVOLVES IS A BIT MORE UNCERTAIN. ONE THING THAT WE
DO EXPECT THOUGH IS THE THREAT FOR MORE SHOWERS AND THUNDERSTORMS AS
THE REGION REMAINS WITHIN FAVORABLE SOUTHWESTERLY FLOW ALOFT.
PREV DISCUSSION... /ISSUED 110 AM CDT FRI MAY 14 2021/
UPDATE...
PLEASE SEE THE 06Z AVIATION FORECAST DISCUSSION BELOW.
AVIATION...
LOW CLOUDS CONTINUE TO DEVELOP OVER THE REGION, WITH ALL SITES
CURRENTLY VFR. THIS WILL CHANGE OVER THE NEXT SEVERAL HOURS AS CIGS
LOWER INTO MVFR. LOW-LEVEL MOISTURE PROFILES SUGGEST CIGS WILL REMAIN
MVFR THROUGH MOST OF THE MORNING HOURS, THEN LIFT INTO THE 4-5K AGL
RANGE BY EARLY AFTERNOON. SOME BRIEF CLEARING OF LOW CLOUDS MAY TAKE
PLACE DURING THE EARLY EVENING HOURS, BUT MVFR CIGS WILL LIKELY
RETURN AGAIN ALONG THE I-35 CORRIDOR 15/04-06Z TIME FRAME.
PRELIMINARY POINT TEMPS/POPS
AUSTIN CAMP MABRY 80 66 82 67 81 / 0 - 50 40 70
AUSTIN BERGSTROM INTL AIRPORT 81 65 82 67 81 / 0 - 40 40 70
NEW BRAUNFELS MUNI AIRPORT 82 67 83 69 83 / 0 - 50 40 60
BURNET MUNI AIRPORT 80 65 79 67 79 / 0 - 50 50 60
DEL RIO INTL AIRPORT 84 70 86 70 89 / - 20 50 40 20
GEORGETOWN MUNI AIRPORT 80 64 82 67 80 / 0 0 40 50 70
HONDO MUNI AIRPORT 83 67 82 68 84 / 0 20 70 60 50
SAN MARCOS MUNI AIRPORT 82 65 82 67 81 / 0 - 50 40 60
LA GRANGE - FAYETTE REGIONAL 82 65 85 70 81 / 0 0 30 30 70
SAN ANTONIO INTL AIRPORT 82 68 81 69 83 / 0 10 60 50 60
STINSON MUNI AIRPORT 84 69 83 70 84 / 0 10 60 50 60
EWX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT-TERM/AVIATION...PLATT
LONG-TERM...MORRIS
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