Severe Thunderstorm Warning 76, NWS Lubbock, TX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LUBBOCK TX
240 PM CDT SUN APR 30 2000

NEED TO RUSH DISCUSSION TODAY...SINCE OFFICE WILL MOST LIKELY GO
INTO SEVERE WEATHER MODE THIS AFTERNOON.

12Z ANALYSIS SHOWS A 500MB CLOSED UPPER LEVEL LOW OVER NORTHERN NM
WITH A 50KT JET MAX ROUNDING THE BASE OF THE TROUGH INTO WEST TX.
VERY STEEP LAPSE RATES WERE NOTED OVER WESTERN AND CENTRAL TX...AS
DELTA TS (700MB TEMP-500MB TEMP) RANGED FROM 22 TO 24 DEGREES.  AT
850 MB DEW POINTS GREATER THAN TEN DEGREES EXTENDED FROM BRO
NORTHWEST TO AMARILLO TO OKLAHOMA CITY...OK...SOUTHEAST TO
GALVESTON...TX. THE DEEPER MOISTURE IS ALREADY IN PLACE EAST OF THE
850MB TROUGH.

THE 17Z SURFACE ANALYSIS SHOWS DENSITY CURRENT/BARRIER JET MOVING
SOUTH THROUGH EASTERN NM AND WESTERN TX PNHDL. A SURFACE LOW WAS
LOCATED JUST NORTH OF LUBBOCK. THE SURFACE DRYLINE EXTENDED
SOUTHEAST FROM THE THE TRIPLE POINT WEST OF AMARILLO TO JUST EAST OF
LUBBOCK SOUTHWARD BETWEEN MIDLAND AND SAN ANGELO. AN OUTFLOW
BOUNDARY EXTENDED ALONG THE RED RIVER VALLEY NORTHWEST ACROSS THE
NORTHEASTERN COUNTIES OF THE FORECAST AREA INTO THE CENTRAL TX
PANHANDLE WHERE IT INTERSECTED THE SURFACE DRYLINE.

ETA MODEL SHOWS THE UPPER LEVEL TROUGH MOVING EAST INTO THE N.W. TX
PNHDL BY THIS EVENING.  THE SURFACE LOW IS FORECASTED TO TRACK
SOUTHEAST TODAY AS DRYLINE PUSHES EAST OFF THE CAPROCK ESCARPMENT
THROUGH THE AFTERNOON HOURS. LOOKS AS IF INTERSECTION OF OUTFLOW
BOUNDARY AND DRYLINE WILL BE OVER THE EASTERN COUNTIES. ETA IS
FORECASTING MID 60 DEWPOINTS TO ADVECT TO THE NORTHWEST ALONG AND
NORTH OF THE OUT FLOW BOUNDARY.  SURFACE WINDS WILL BE BACKED ALONG
AND NORTH OF THE OUTFLOW BOUNDARY OVER PORTIONS OF NORTH TX/SOUTHWEST
OK AND THE EASTERN SECTION OF THE FORECAST AREA. THE VERTICAL WIND
SHEAR PROFILE WILL SUPPORT SUPERCELLULAR CONVECTION TO DEVELOP EAST
OF THE DRYLINE AND ALONG AND NORTH OF THE OUTFLOW BOUNDARY THIS
AFTERNOON. ATMOSPHERE IS QUITE UNSTABLE GIVEN STEEP LAPSE
RATES...MID 60S DEWPOINTS...LOW TO MID 80 TEMPERATURES AND -15
DEGREES AT 500MB.  I ESTIMATED CAPES TO BE AT OR ABOVE 3000 J/KG
WHICH WILL SUPPORT INTENSE UPDRAFT.  THE PRIMARY THREAT WITH THESE
SUPERCELL THUNDERSTORMS WILL BE LARGE HAIL...HOWEVER ALONG AND NORTH
OF THE OUTFLOW BOUNDARY WHERE SURFACE WINDS ARE BACKED AND LOWER
TEMPERATURE/DEWPOINT TEMPERATURE DEPRESSIONS WILL EXIST A FEW
TORNADOES MAY BE POSSIBLE. DURING THE LATE EVENING HOURS THE
ISOLATED THUNDERSTORMS WILL PROBABLY MERGE INTO A COMPLEX OF STORMS
AND MOVE EAST OUT OF THE FORECAST AREA.

TONIGHT THE COLD FRONT WILL MOVE SOUTHWARD ACROSS THE REGION.  THERE
MAY BE SOME WEAK ISENTROPIC LIFT OVER EASTERN SECTION OF THE
FORECAST AREA...OVER THE WESTERN HALF OF THE FORECAST AREA THE COLD
AIR ADVECTION WILL BE TOO INTENSE FOR MUCH PRECIPITATION...BUT I
WILL GO WITH A SLIGHT CHANCE IN CASE OF DRIZZLE OR LIGHT SHOWERS.

ON MONDAY THE ETA MODEL SHOWS THE UPPER LOW MOVING RIGHT OVER THE
REGION...SO WITH COLDER AIR ALOFT ALONG ENOUGH RESIDUAL MOISTURE...
THERE MAY BE A CHANCE OF SHOWERS AND THUNDERSTORMS DEVELOPING DURING
THE AFTERNOON HOURS.

EXTENDED OUTLOOK...BOTH THE CANADIAN AND MRF MODELS CONTINUE TO SHOW
THE UPPER LOW OVER THE REGION...SO I WILL CONTINUE THE CHANCES OF
AFTERNOON SHOWERS AND THUNDERSTORMS ON TUESDAY AFTERNOON.  CANADIAN
AND ECMWF SHOW UPPER LOW SLOWLY MOVING TOWARDS SOUTHEAST TX AND A
SOUTHERN STREAM RIDGE BUILDING OVER THE REGION TOWARDS THE END OF
THE WEEK.  EXPECT DRY CONDITIONS AND WARMER TEMPERATURES FROM
WEDNESDAY THROUGH FRIDAY.

I WILL ISSUE A FLASH FLOOD WATCH TONIGHT OVER THE NORTHEAST FOUR
COUNTIES OF THE CWFA. THIS IS DUE TO REPEATED HEAVY RAINFALL LAST
NIGHT AND TROUGH THE MORNING HOURS OVER COTTLE AND CHILDRESS
COUNTIES....WHERE STORM TOTALS HAVE BEEN NEARLY 5 INCHES.  THE
POTENTIAL EXIST FOR WIDE SPREAD HEAVY RAINFALL THIS AFTERNOON AND
THROUGH THE EVENING HOURS. THE WATCH WILL BE IN EFFECT UNTIL THE
NEXT ZONE ISSUANCE AT 430 AM.

FRIONA     45/62/42/70 22-2        BROWNFIELD  47/67/45/74 22-2
TULIA      45/63/43/72 33-3        LUBBOCK     47/66/45/74 22-2
CHILDRESS  50/67/47/70 63-3        ASPERMONT   53/72/50/74 53-3

.LBB...

TORNADO WATCH UNTIL 8PM CDT TXZ 025-026>031-032>037-038>043-044

FLASH FLOOD WATCH UNTIL 430AM CDT TXZ 025-026>031-032

TXZ023>026-029>032-301600-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LUBBOCK TX
1017 AM CDT SUN APR 30 2000

THE SEVERE THUNDERSTORM WATCH IN EFFECT UNTIL 11 AM HAS BEEN
CANCELED FOR THE FOLLOWING COUNTIES...

SWISHER...BRISCOE...HALL...CHILDRESS...HALE...FLOYD...MOTLEY AND
COTTLE

STAY TUNED TO NOAA WEATHER RADIO...TV...OR YOUR LOCAL NEWS SOURCE
FOR THE LATEST WEATHER INFORMATION.

JAMES

TXZ021>044-301900-

AREA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE LUBBOCK TX
1130 AM CDT SUN APR 30 2000

...ANOTHER ROUND OF SEVERE WEATHER EXPECTED THIS AFTERNOON AND
EVENING...

THERE IS A SLIGHT TO MODERATE RISK OF SEVERE THUNDERSTORMS THIS
AFTERNOON AND EVENING ACROSS EASTERN PORTIONS OF THE SOUTH PLAINS...
EXTREME SOUTHERN PANHANDLE AND LOW ROLLING PLAINS. THE MODERATE RISK
AREA IS GENERALLY ALONG AND EAST OF A LINE FROM MATADOR TO SPUR TO
SNYDER. THE SLIGHT RISK AREA IS EAST OF A LINE FROM PLAINVIEW TO POST
TO BIG SPRING. THE LUBBOCK METRO AREA IS NOT INCLUDED IN THE SLIGHT
RISK AREA AT THIS TIME.

A VERY UNSTABLE ATMOSPHERE CONTINUES TO RESIDE ACROSS THE REGION LATE
THIS MORNING. SEVERAL FACTORS WILL COME TOGETHER TO PRODUCE A CHANCE
OF SEVERE WEATHER BY THIS AFTERNOON. A COLD FRONT MOVING ACROSS THE
NORTHERN TEXAS PANHANDLE WILL CONTINUE TO SLOWLY MOVE SOUTH TODAY. IN
ADDITION A VERY PRONOUNCED DRYLINE WILL PUSH EAST. THE COMBINATION OF
THESE TWO FEATURES COUPLED WITH COLD TEMPERATURES ALOFT AND A VERY
UNSTABLE ATMOSPHERE WILL AID IN THE PRODUCTION OF SHOWERS AND
THUNDERSTORMS ACROSS THE RISK AREAS. THESE STORMS WILL HAVE THE
POTENTIAL TO BECOME SEVERE AND PRODUCE LARGE...DAMAGING HAIL...HIGH
WINDS IN EXCESS OF 60 MPH AND TORNADOES. IN ADDITION TO SEVERE
WEATHER...FLOODING RAINS MAY ALSO DEVELOP. RAINFALL AMOUNTS OF 1 TO 3
INCHES WITH LOCALIZED AMOUNTS OF 4 TO 5 INCHES WERE COMMON ACROSS
LOCATIONS EAST OF THE CAP ROCK LAST NIGHT AND EARLIER THIS MORNING.
SHOULD HEAVY RAINS DEVELOP...FLOODING WILL BECOME A PROBLEM ACROSS
THESE AREAS.

THUNDERSTORMS ARE EXPECTED TO DEVELOP BY MID AFTERNOON AND QUICKLY
BECOME SEVERE. A SEVERE THUNDERSTORM OR TORNADO WATCH MAY BE
REQUIRED LATER TODAY.

ACTIVATION OF SPOTTER GROUPS AND EMERGENCY MANAGEMENT WILL LIKELY BE
NEEDED LATER THIS AFTERNOON.

THIS IS A DEVELOPING WEATHER SITUATION. PEOPLE ACROSS THE REGION
SHOULD CAREFULLY MONITOR THE LATEST WEATHER INFORMATION. STAY TUNED
TO NOAA WEATHER RADIO...TV...OR YOUR LOCAL NEWS SOURCE FOR LATER
STATEMENTS AND FORECASTS FROM THE NATIONAL WEATHER SERVICE IN
LUBBOCK.

ST