Severe Thunderstorm Warning 253, NWS San Angelo, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
156 PM CST SAT OCT 31 1998

SQUALL LINE IS DEVELOPING RAPIDLY IN WEST TEXAS IN THE VICINITY OF
THE PACIFIC FRONT. THIS FEATURE WILL PUSH SLOWLY TO THE EAST WHILE
MOST OF THE CELLS MOVE QUICKLY TO THE NORTH-NORTHEAST...PROMPTING
THE ISSUANCE OF A SEVERE THUNDERSTORM WATCH BY SPC WHICH EXTENDS
INTO THE WESTERN HALF OF OUR REGION THROUGH 8 PM.

ALTHOUGH THE SQUALL LINE WILL BE THE MAIN WEATHER FEATURE THIS
AFTERNOON AND EVENING...THE RAIN WILL CONTINUE PAST MIDNIGHT AS THE
UPPER LOW NOW IN SOUTHWEST NEW MEXICO LAGS BEHIND THE FRONT AND
PASSES THROUGH OUR REGION EARLY SUNDAY MORNING...PROVIDING AMPLE
LIFT AND DYNAMICS FOR A LARGE AREA OF POST FRONTAL RAIN WITH
EMBEDDED THUNDERSTORMS. MODELS SHOW OUR REGION UNDER THE FAVORABLE
RIGHT ENTRANCE REGION OF THE MAIN UPPER LEVEL JET STREAK BETWEEN 00Z
AND 12Z...AND HINT AT A MORE SUBTLE SPEED MAXIMUM WHICH WOULD
FURTHER ENHANCE UPWARD MOTION AND UPPER LEVEL DIVERGENCE STARTING
LATER THIS EVENING. BY MIDNIGHT...THE LOW LEVEL JET AND MID LEVEL
WIND MAXIMUM ALSO COME INTO PLAY FOR ENHANCING RAIN CHANCES OVER OUR
REGION IN A VERY MOIST ATMOSPHERE CONTAINING PRECIPITABLE WATERS
AROUND 1.5 INCHES...WHICH IS AROUND 200 PERCENT OF THE SEASONAL
NORMAL. OVERALL...THE POTENTIAL FOR WIDESPREAD HEAVY RAIN OF GREATER
THAN ONE INCH LOOKS GOOD FOR NEARLY ALL OF OUR REGION TONIGHT. THE
FAST MOVING CELLS IN THE SQUALL LINE ARE NOT QUITE LINED UP IN A
TRAIN ECHO PATTERN...AND OUR REGION HAS BEEN DRY WITH HIGH FLOOD
GUIDANCE VALUES SO A FLASH FLOOD WATCH IS PROBABLY NOT NEEDED...BUT
MENTION OF LOCALLY HEAVY RAIN IN THE FORECAST IS RECOMMENDED.

THE RAIN WILL LIKELY END BY SUNRISE OVER THE WESTERN HALF OF OUR
REGION...AND LINGER INTO THE MID AND LATE MORNING FOR OUR EASTERN
COUNTIES. BEHIND THE FRONT...THE ATMOSPHERE WILL DRY OUT BUT WITH
CYCLONIC 500 MB FLOW CONTINUING THROUGH THE AFTERNOON...MOST AREAS
WILL PROBABLY END UP MOSTLY CLOUDY DUE TO THE WRAP-AROUND CLOUDS
FROM THE UPPER LOW...ESPECIALLY FOR OUR NORTHERN COUNTIES. GUIDANCE
HIGHS FOR SUNDAY ARE A FEW DEGREES LOWER FROM PREVIOUS RUNS WHICH
LOOKS APPROPRIATE FOR THE CURRENT FORECAST.

BEYOND SUNDAY...TRANQUIL WEATHER WILL RETURN TO THE REGION FOR
THE EARLY PART OF THE WORK WEEK WITH SEASONABLY PLEASANT DAYS AND
COOL NIGHTS EXPECTED.

ABI 055/064 +4
SJT 056/066 +3
JCT 058/067 94

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TXZ049-053-054-064>066-071>073-076>078-098-099-113-114-127-128-
139-140-154-155-168>170-011415-

WEST CENTRAL TEXAS THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE SAN ANGELO TX
229 PM CST SAT OCT 31 1998

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER WEST CENTRAL
TEXAS LATE THIS AFTERNOON AND TONIGHT...LOCALLY HEAVY RAINFALL IS
ALSO LIKELY TONIGHT...

A STRONG UPPER LEVEL STORM SYSTEM OVER SOUTHERN NEW MEXICO WILL MOVE
ACROSS TEXAS TONIGHT...WHILE A PACIFIC COLD FRONT CURRENTLY OVER
WEST TEXAS WILL ALSO MOVE ACROSS THE REGION FROM WEST TO EAST DURING
THE EVENING AND LATE NIGHT HOURS. A LINE OF THUNDERSTORMS WILL
ACCOMPANY THE PASSAGE OF THIS COLD FRONT. THESE STORMS WILL LIKELY
AFFECT AREAS ALONG AND WEST OF AN ABILENE TO SAN ANGELO TO SONORA
LINE BETWEEN 6 AND 10 PM...AND AFFECT AREAS EAST OF THIS LINE DURING
THE LATE EVENING HOURS THROUGH 1 AM. DUE TO STRONG WINDS ALOFT
AND SUFFICIENT UPPER LEVEL SUPPORT...SOME OF THESE STORMS MAY BECOME
SEVERE WITH DAMAGING WINDS IN EXCESS OF 60 MPH AND HAIL UP TO GOLF
BALL SIZE.

THE THREAT OF RAIN WILL CONTINUE AFTER MIDNIGHT OVER MOST OF
WEST CENTRAL TEXAS AS DEEP MOISTURE REMAINS IN PLACE BEHIND
THE COLD FRONT. ALTHOUGH THE CHANCE FOR SEVERE WEATHER WILL DIMINISH
AFTER MIDNIGHT...HEAVY RAINFALL IS LIKELY WITH MINOR FLOODING OF LOW
WATER CROSSINGS AND POOR DRAINAGE AREAS POSSIBLE.

TRICK-OR-TREATERS AND PEOPLE PLANNING OUTDOOR HALLOWEEN ACTIVITIES
AND SHOULD CLOSELY MONITOR THE WEATHER CONDITIONS THIS EVENING AND
BE PREPARED TO SEEK SHELTER IN A STURDY BUILDING IF A THUNDERSTORM
APPROACHES.

SPOTTER ACTIVATION WILL LIKELY BE NEEDED.

FOR THE SOUTHWEST TEXAS AND SOUTHEAST NEW MEXICO OUTLOOK SEE
PRODUCT LBBSPSMAF. FOR THE SOUTH CENTRAL TEXAS OUTLOOK SEE PRODUCT
SATSPSSAT.

THIS IS THE FINAL ROUTINE ISSUANCE OF THE THUNDERSTORM OUTLOOK UNTIL
MARCH 15 1999. HOWEVER...THIS OUTLOOK WILL BE ISSUED AS NEEDED
THROUGH THE LATE FALL AND WINTER SEASONS WHENEVER THUNDERSTORMS
THREATEN ANY PORTION OF WEST CENTRAL TEXAS.

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