Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS64 KEWX 231153
AFDEWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
653 AM CDT SAT MAY 23 2015

.AVIATION... /12Z TAF UPDATE/
ACTIVE CONVECTION IS IMPACTING AUS AT THE TIME OF TAF ISSUANCE.
THE SCATTERED SHOWERS AND THUNDERSTORMS LOOK TO BE PULLING NORTH
OF THE SAT/SSF VCNTYS FOR A FEW HOURS AND COULD LIFT NORTH OF THE
AUS AREA IN THE NEXT HOUR OR TWO AS WELL. DEEP TROPICAL MOISTURE
AND ANOTHER RIPPLE OF ENERGY NEAR DRT COULD BEGIN TO IMPACT THE
I-35 SITES AGAIN BY 15Z. CONVECTION SHOULD BE SCATTERED SO TIMING
IS IN LOW CONFIDENCE FOR TODAY. CONFIDIDENCE INCREASES FOR THE
PREVAILING THUNDER PERIOD...ALTHOUGH THE TIME WINDOW MAY BE ABLE
TO COMPRESS ONCE THE MUCH ANTICIPATED STORM COMPLEX BEGINS TO TAKE
SHAPE. AFTER THE COMPLEX IS SPECULATED TO PASS EAST OF I-35
TOWARD DAYBREAK...WILL CONTINUE PREVAILING SHOWERS...WITH SOME
POSSIBLE FURTHER IMPROVEMENTS TO FOLLOW DURING THE DAYLIGHT HOURS
SUNDAY. WILL KEEP CONDITIONS FAIRLY PESSEMISTIC IN CASE THE SYSTEM
SLOWS DOWN.

&&

.PREV DISCUSSION... /ISSUED 314 AM CDT SAT MAY 23 2015/

SHORT TERM (TODAY THROUGH SUNDAY)...
MODERATE TO HEAVY RAINFALL IS GETTING AN EARLY START WITH
CONVECTION INCREASING WEST OF HIGHWAY 83. THIS IS ALL ASSOCIATED
WITH INCREASING LIFT AHEAD OF THE MAIN UPPER LOW WHICH IS STILL
OVER UTAH/ARIZONA PER 00Z UPPER AIR ANALYSIS AND LATEST WATER
VAPOR IMAGERY. RAINFALL RATES WITH THIS ACTIVITY ARE GENERALLY AT
1-2 INCHES PER HOUR AND WE HAVE ALREADY ISSUED ONE FLOOD ADVISORY.
THE HRRR IS ZEROING IN ON THIS AREA WHERE RAIN IS CURRENTLY
INCREASING AND IS COMING UP WITH SOME HIGH TOTALS THIS MORNING.
BECAUSE OF THIS EARLY THREAT OF HEAVY RAINFALL...WILL GO AHEAD
AND START THE FLASH FLOOD WATCH NOW. THIS WILL BE A BIT TOO EARLY
FOR THE EASTERN ZONES...BUT WANT TO AVOID CONFUSION WITH A
SEGMENTED PRODUCT. HIGH-RES MODEL GUIDANCE CONTINUES TO SHOW THE
WESTERN CWA AS THE FAVORED AREA FOR CONVECTION LATER THIS MORNING
BEFORE SPREADING ACROSS THE AREA THIS AFTERNOON. RAIN LOOKS LIKELY
FOR TODAY WITH 60/70 POPS ACROSS THE CWA. INDIVIDUAL CELLS COULD
CONTAIN HEAVY RAINFALL AND SOME TRAINING OF CELLS IS ALSO
POSSIBLE.

THE MAIN FORCING WITH THIS INITIAL WAVE OF LIFT ASSOCIATED WITH
THE UPPER LOW WILL BEGIN TO ARRIVE TO THE WESTERN ZONES LATE THIS
AFTERNOON AND EVENING. CONFIDENCE IS HIGH THAT A LINE OF SHOWERS
AND THUNDERSTORMS WILL DEVELOP WITH THIS LIFT AND STRETCH ACROSS A
LARGE PORTION OF TEXAS. THERE ARE SOME DISCREPANCIES WITH THE
GUIDANCE ON THE EXACT TIMING OF THIS WITH MOST MODELS SOMEWHERE
BETWEEN THE 21Z TO 03Z TIME FRAME...WITH SOME OF THE HIGH-RES
GUIDANCE BEING THE EARLIEST. THIS LINE IS EXPECTED TO SLOWLY MARCH
THROUGH THE CWA OVERNIGHT AND IS EXPECTED TO AVERAGE A QUICK 1-3
INCHES OF RAIN AS IT MOVES ACROSS. OVERNIGHT RAIN ON TOP OF ANY
RAINFALL THAT OCCURS TODAY WILL NOT BE ABLE TO SOAK INTO THE
GROUND...AS SOILS REMAIN QUITE SATURATED FROM A VERY WET SPRING.
MOST OF THE RAIN WILL RUNOFF INTO CREEKS...STREAMS AND RIVERS AND
FLOODING IS ONCE AGAIN LIKELY.

ALTHOUGH FLOODING RAINS IS OF THE HIGHEST CONCERN ON THIS HOLIDAY
WEEKEND...THERE IS THE THREAT OF SEVERE WEATHER AS WELL. SEVERE
PARAMETERS ARE FAVORABLE FOR SEVERE STORMS...BUT AM CONCERNED WITH
THE HIGHER COVERAGE OF STORMS AND THE EFFECT THAT COULD HAVE BY
CLUTTERING UP THE NEAR-STORM ENVIRONMENT. HOWEVER...CANT RULE OUT
BOWING SEGMENTS WITHIN THE MAIN LINE THAT COULD PRODUCE SOME
SEVERE WINDS. ALSO...LOW-LEVEL WINDS WILL INCREASE AND SOME
TURNING IN THE PROFILE WILL POSE AN ISOLATED TORNADO THREAT WITH
ANY STRONGER LINE SEGMENTS AS WELL AS THE MAIN LINE MOVES THROUGH
THE AREA.

BY SUNDAY MORNING...THE LINE OF STORMS WILL BE NEARING THE EASTERN
COUNTIES AND SHOULD MOVE OUT OF THE CWA SOMETIME AROUND 18Z. THE
THREAT OF FLOODING RAINS AND SOME SEVERE WEATHER WILL CONTINUE
SUNDAY MORNING. BY SUNDAY AFTERNOON...CAPE VALUES INCREASE TO
ABOVE 3000 J/KG WHICH IS SOMEWHAT INITIALLY CONCERNING.
HOWEVER...FORECAST SOUNDINGS SHOW DECENT AMOUNTS OF DRYING ALOFT
BEHIND THE INITIAL WAVE WHICH SHOULD LIMIT ACTIVITY. ALSO...THE
ENVIRONMENT SHOULD BE PRETTY WORKED OVER FROM THE OVERNIGHT AND
MORNING ACTIVITY. THE ONE AREA TO WATCH WILL BE THE WESTERN
COUNTIES WHERE THE MOST RECOVERY TIME WILL BE AND SOME HIGH-RES
MEMBERS ARE SHOWING THE POTENTIAL FOR REDEVELOPMENT SUNDAY
AFTERNOON IN THIS GENERAL AREA.

RAINFALL AMOUNTS THIS MORNING THROUGH SUNDAY WILL AVERAGE 1-4
INCHES WITH THE HIGHER AMOUNTS NEAR THE I-35 CORRIDOR. WE MUST
CONTINUE TO STRESS TO ANYONE ON LOCAL RIVERS AND LAKES THIS
HOLIDAY WEEKEND TO PAY VERY CLOSE ATTENTION TO THE WEATHER AND ANY
WARNINGS THAT ARE ISSUED. HAVE A PLAN IN PLACE TO SEEK SHELTER
AND ALWAYS REMEMBER TO TURN AROUND...DONT DROWN.

LONG TERM (SUNDAY NIGHT THROUGH FRIDAY)...
SHOULD SEE A LULL IN ACTIVITY EARLY SUNDAY NIGHT...BUT THIS
SHOULD UNFORTUNATELY BE BRIEF. CURRENTLY ON WATER VAPOR
IMAGERY...ANOTHER IMPULSE ASSOCIATED WITH THE MAIN UPPER LOW CAN
BE SEEN NEAR THE WASHINGTON AND OREGON BORDER. 00Z GUIDANCE SEEMS
TO HAVE PICKED UP ON THIS FEATURE QUITE WELL AND BRINGS IT INTO
TEXAS FOR MONDAY /MEMORIAL DAY/. SUBSEQUENTLY...THE 00Z MODEL
GUIDANCE HAS INCREASED THE QPF AMOUNTS FORECASTED FOR MONDAY
AFTERNOON. THE GFS IS THE HIGHEST OF ALL GUIDANCE WITH ANOTHER 2
INCHES OF RAIN FOR THE I-35 CORRIDOR. WENT AHEAD AND INCREASED
RAIN TOTALS IN THE OFFICIAL FORECAST...BUT NOT QUITE AS HIGH AS
THE GFS IS ADVERTISING. IF CONFIDENCE INCREASES THAT UP TO ANOTHER
2 INCHES OF RAIN WILL FALL ON MONDAY....THE FLASH FLOOD WATCH WILL
NEED TO BE EXTENDED AT A LATER TIME. CAPE/SHEAR VALUES WILL
SUPPORT THE THREAT OF SEVERE WEATHER AS WELL. FORECAST SOUNDINGS
DUE SHOW THE THREAT FOR HAIL...DAMAGING WINDS AND POSSIBLE
ISOLATED TORNADOES FOR MONDAY AFTERNOON. THE OVERALL THREAT FOR
TORNADOES WILL BE HIGHLY DEPENDENT ON THE OVERALL COVERAGE OF
ACTIVITY AND IF ANY DISCRETE SUPERCELLS ARE AVAILABLE TO DEVELOP.
AGAIN...ANYONE OUTDOORS ON THE HOLIDAY NEED TO MAKE SURE TO HAVE A
PLAN AND BE READY TO SEEK SHELTER.

THE UPPER AIR PATTERN BECOMES MORE ZONAL ON TUESDAY WITH WEAK
RIDGING ON WEDNESDAY. OVERALL COVERAGE OF ACTIVITY SHOULD DECREASE
FOR MID-WEEK. POPS WILL SLIGHTLY INCREASE ONCE AGAIN TOWARDS THE
END OF THE WORK WEEK AS THE NEXT DISTURBANCE NEARS THE AREA.

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              81  68  81  71  82 /  60  90  60  40  60
AUSTIN BERGSTROM INTL AIRPORT  81  68  81  70  82 /  60  90  70  40  60
NEW BRAUNFELS MUNI AIRPORT     82  68  82  71  82 /  60  90  60  40  60
BURNET MUNI AIRPORT            79  66  80  69  81 /  50  90  60  30  50
DEL RIO INTL AIRPORT           82  68  89  70  87 /  70  70  30  20  40
GEORGETOWN MUNI AIRPORT        80  68  80  70  82 /  50  90  60  40  60
HONDO MUNI AIRPORT             82  66  84  70  82 /  70  90  50  30  60
SAN MARCOS MUNI AIRPORT        81  68  80  70  82 /  60  90  60  40  60
LA GRANGE - FAYETTE REGIONAL   83  69  80  71  82 /  40  80  80  50  70
SAN ANTONIO INTL AIRPORT       82  68  82  72  83 /  60  90  60  30  60
STINSON MUNI AIRPORT           83  69  83  72  83 /  60  90  60  30  60

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH SUNDAY EVENING FOR THE FOLLOWING
COUNTIES: ATASCOSA...BANDERA...BASTROP...BEXAR...BLANCO...BURNET...
CALDWELL...COMAL...DE WITT...DIMMIT...EDWARDS...FAYETTE...FRIO...
GILLESPIE...GONZALES...GUADALUPE...HAYS...KARNES...KENDALL...KERR...
KINNEY...LAVACA...LEE...LLANO...MAVERICK...MEDINA...REAL...TRAVIS...
UVALDE...VAL VERDE...WILLIAMSON...WILSON...ZAVALA.

&&

$$

MESOSCALE/AVIATION...OAKS
SYNOPTIC/GRIDS...HAMPSHIRE



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.