Hail in Texas, September 20, 2001

TEXAS/OKLAHOMA PANHANDLES FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AMARILLO TX
237 PM CDT THU SEP 20 2001

THE MAIN FORECAST DIFFICULTY WILL BE PRECIPITATION AND TEMPERATURES.
SURFACE ANALYSIS SHOWED A WEAK DRYLINE IN PLACE ACROSS THE
PANHANDLES FROM THE NORTHCENTRAL ZONE EXTENDING SOUTHWEST. A LOW
PRESSURE TROUGH WAS DRAPED ACROSS THE REGION WITH A SHORTWAVE
EMBEDDED IN NORTHWEST FLOW OVER NORTHEASTERN NEW MEXICO. AS THIS
SHORTWAVE PUSHES SOUTHEAST THIS AFTERNOON THUNDERSTORMS WILL
INITIATE ALONG THE DRYLINE. WITH A VERY UNSTABLE AIR MASS ACROSS
THE CENTRAL AND EASTERN ZONES...SEVERE THUNDERSTORMS WILL BE
POSSIBLE TONIGHT ESPECIALLY AS THE LOW-LEVEL JET DEVELOPS TO THE
SOUTHEAST THIS EVENING. A COLD FRONT PUSHING SOUTH ACROSS WESTERN
KANSAS AND EASTERN COLORADO WILL PUSH THROUGH THE FORECAST AREA
TONIGHT BUT MAY HANG UP OVER THE SOUTHERN ZONES FRIDAY. THIS WILL
COOL TEMPERATURES DOWN ABOUT 10 DEGREES COMPARED TO TODAYS
TEMPERATURES. PLENTY OF LOW-LEVEL MOISTURE WILL STILL BE IN PLACE...
HOWEVER ANTICYCLONIC FLOW ALOFT WITH SUBSIDENCE BEHIND AN EXITING
SHORTWAVE COULD LIMIT CONVECTION IN THE EASTERN AND CENTRAL ZONES
FRIDAY AFTERNOON AND EVENING. HOWEVER...ADDITIONAL VORT MAX ENERGY
SHOULD DEVELOP OVER THE MOUNTAINS AND PUSH INTO THE WESTERN HIGH
PLAINS FRIDAY NIGHT. THIS WILL HELP SUSTAIN MOUNTAIN STORMS OVERNIGHT
BRINGING A CHANCE OF PRECIPITATION TO THE WESTERN ZONES AND POSSIBLY
INTO THE CENTRAL ZONES FRIDAY NIGHT. NORTHWEST FLOW CONTINUES
SATURDAY WITH ADDITIONAL SHORTWAVE ACTIVITY POSSIBLE. WITH RETURN
FLOW AND A LEE TROUGH SETTING UP...ADDITIONAL STORMS MAY DEVELOP
ACROSS THE FORECAST AREA.

FOR THE LATER PERIODS...MEDIUM RANGE MODELS CONTINUE THE NORTHWEST
FLOW SUNDAY USHERING DOWN A COLD FRONT ACROSS THE AREA. IF THIS
HAPPENS...COLD AIR ADVECTION WOULD INCREASE. IN ADDITION...THE
MODELS AMPLIFY A RIDGE IN THE SOUTHWESTERN STATES MONDAY. WITH
NORTHERLY WINDS ALOFT RESULTING...MOUNTAIN CONVECTION WOULD HUG THE
MOUNTAINS MONDAY AND TUESDAY...REDUCING THE LIKELIHOOD OF
PRECIPITATION IN THE PANHANDLES. SURFACE HIGH PRESSURE BEHIND THE
FRONT WOULD LOWER TEMPERATURES TEMPERATURES DURING THE EARLY PART OF
THE WEEK WITH A GRADUAL WARM UP POSSIBLE BY MID WEEK.

PRELIM CCF...
AMA 59/83 60/86 58 322
DHT 56/81 57/84 55 123

.AMA...
TX...NONE.
OK...NONE.

CB

OKZ001>003-TXZ001>020-202100-

TEXAS/OKLAHOMA PANHANDLES THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE AMARILLO TX
110 PM CDT THU SEP 20 2001

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS A LARGE PORTION
OF THE TEXAS AND OKLAHOMA PANHANDLES THIS AFTERNOON AND THIS EVENING.
THE AREA AT RISK IS GENERALLY EAST OF A LINE FROM GUYMON...TO DUMAS
...TO GLENRIO.

A WARM...MOIST...AND VERY UNSTABLE AIRMASS IS IN PLACE ACROSS MUCH OF
THE PANHANDLES THIS AFTERNOON. A SURFACE LOW PRESSURE CENTER WAS
LOCATED NEAR GUYMON EARLY THIS AFTERNOON...WITH A DRYLINE EXTENDING
TO ITS SOUTHWEST...TO NEAR GLENRIO.

SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG THE DRYLINE
THIS AFTERNOON AND EVENING...AND WILL THEN MOVE TO THE SOUTHEAST. DUE
TO THE INSTABILITY ALREADY IN PLACE...STORMS WILL HAVE THE POTENTIAL
TO STRENGTHEN QUICKLY. SOME OF THE STRONGER STORMS WILL LIKELY BECOME
SEVERE.

THE MAIN SEVERE WEATHER THREAT FROM THE STORMS WILL BE LARGE HAIL...
DAMAGING WINDS...AND HEAVY RAIN. THE TURNING OF WINDS WITH HEIGHT MAY
BECOME FAVORABLE FOR THE DEVELOPMENT OF ISOLATED TORNADOES.

SPOTTER GROUPS AND EMERGENCY MANAGEMENT OFFICIALS ACROSS ALL BUT THE
NORTHWEST PART OF THE TEXAS PANHANDLE...AND THE WESTERN OKLAHOMA
PANHANDLE...SHOULD REMAIN ALERT FOR POSSIBLE ACTIVATION THIS
AFTERNOON OR THIS EVENING.

COCKRELL