Tornadoes and Hail in Oklahoma, May 20, 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
340 PM CDT SUN MAY 20 2001

TSTMS BEGINNING TO RAPIDLY DEVELOP THIS AFTERNOON ACROSS OKLAHOMA IN
AREAS OF WEAK LOW LEVEL CONVERGENCE/CONFLUENCE. MEANWHILE... UPPER
TROUGH OVER WESTERN KANSAS INTO THE TX PNHDL ALSO MOVING ACROSS THE
AREA THE NEXT SEVERAL HOURS. EXPECT TSTMS TO INCREASE IN COVERAGE
THROUGH THE EVENING. MEANWHILE... STRONG COLD FRONT MOVING THROUGH
WESTERN KANSAS WILL REACH NORTHWEST OKLAHOMA AROUND MIDNIGHT...AND
MOVE THROUGH THE RED RIVER VALLEY BY MORNING. ADDITIONAL TSTMS WILL
BE POSSIBLE ALONG THE FRONT... ALTHOUGH EXTENT OF COVERAGE A LITTLE
UNCERTAIN. PASSAGE OF THE KANSAS WAVE TO THE EAST OF THE AREA AND
STABILIZATION OF AIRMASS BY CURRENT CONVECTION COULD REDUCE THE
EXTENT OF ADDITIONAL DEVELOPMENT. WILL LEAVE IN 20 TO 30 PCT CHANCE
FOR SHWRS/TSTMS BEHIND THE FRONT ON MONDAY AS A SECONDARY UPPER WAVE
BRUSHES THE AREA. STRONG JET MAX DROPPING SOUTHEAST THROUGH THE
NORTHWEST U.S. WILL DIG OUT A DEEP UPPER TROUGH OVER THE MISSISSIPPI
VALLEY BY EARLY TUESDAY. THIS FEATURE WILL MOVE VERY SLOWLY OVER THE
NEXT SEVERAL DAYS... AND AS RESULT WILL BRING SEVERAL SHOTS OF COOL
AIR TO THE REGION. BELOW NORMAL TEMPS EXPECT MOST AREAS THROUGH MUCH
OF THE WEEK.

FCSTID = 32
OKC   56  64  46  72 /  70  20   0   0
HBR   54  65  44  75 /  50  20   0   0
SPS   59  68  46  76 /  50  20   0   0
GAG   48  62  40  73 /j  50  30   0   0
PNC   52  63  44  71 /  70  30   0   0
DUA   62  68  47  75 /  70  30  10   0

.OUN...
OK...NONE.
TX...NONE.

LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
1028 AM CDT SUN MAY 20 2001

TIME (CDT) .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0223 PM    4 W ALTUS                 OK   TORNADO
05/19/01   JACKSON                        LASTED APPROXIMATELY
                                          TWO MINUTES...REPORTED
                                          BY METEOROLOGIST
 
KT

OKZ004>048-050>052-TXZ083>090-202030-

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE NORMAN OK
100 PM CDT SUN MAY 20 2001

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING OVER PARTS OF CENTRAL OKLAHOMA.  THE MODERATE RISK AREA IS
ALONG AND EAST OF INTERSTATE 35...AND SOUTHEAST OF A OKLAHOMA CITY
TO TULSA LINE.  TO THE WEST OF THE MODERATE RISK AREA... THERE IS A
SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE REMAINDER OF CENTRAL
AND PORTIONS OF WESTERN OKLAHOMA AND WESTERN NORTH TEXAS.  THE
SLIGHT RISK AREA IS GENERALLY EAST OF A WICHITA FALLS TO THOMAS
LINE...AND NORTH OF A GAGE TO CEILING LINE.  LARGE HAIL... DAMAGING
WIND AND TORNADOES WILL BE POSSIBLE.

CLOUDS WILL CONTINUE TO THIN ACROSS MOST OF CENTRAL OKLAHOMA
THIS AFTERNOON WHICH WILL ALLOW FOR STRONG HEATING AND
DESTABILIZATION.  THE COMBINATION OF A STRONG SUBTROPICAL JET MOVING
ACROSS NORTH TEXAS...A MID LEVEL TROUGH OVER WESTERN OKLAHOMA AND
SURFACE CONVERGENCE WILL LIKELY RESULT IN THUNDERSTORMS DEVELOPMENT
BY EARLY TO MID AFTERNOON.   THE BEST CHANCE FOR INITIAL DEVELOPMENT
APPEARS TO BE JUST WEST OF THE MODERATE RISK AREA.  SOME OF THESE
STORMS ARE LIKELY TO BECOME SUPERCELLS WITH THE POTENTIAL TO PRODUCE
VERY LARGE HAIL AND DAMAGING WIND GUSTS. LOW LEVEL WIND SHEAR MAY
ALSO BE ENHANCED ALONG AND NORTH OF THE RESIDUAL OUTFLOW BOUNDARY
FROM MORNING CONVECTION... AND ANY SUPERCELLS THAT ARE ABLE TO
INTERACT WITH AREAS OF ENHANCED LOW LEVEL SHEAR WILL BE CAPABLE OF
PRODUCING TORNADOES.

A STRONG COLD FRONT WILL ALSO APPROACH OKLAHOMA FROM THE NORTH THIS
EVENING.  OTHER STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED TO
DEVELOP OVER KANSAS ALONG THE FRONT LATE THIS AFTERNOON AND ORGANIZE
INTO A SQUALL LINE.  THIS SQUALL LINE WILL SWEEP SOUTHEASTWARD
ACROSS MUCH OF OKLAHOMA AND WESTERN NORTH TEXAS WITH THE COLD FRONT
OVERNIGHT WITH THE POTENTIAL FOR DAMAGING WINDS AND LARGE HAIL.

PERSONS ACROSS THE AREA TODAY SHOULD PAY ATTENTION TO THE LATEST
WEATHER INFORMATION AND BE ALERT FOR FURTHER UPDATES ON THE SEVERE
WEATHER SITUATION. EMERGENCY MANAGERS AND STORM SPOTTER GROUPS
SHOULD BE PREPARED FOR SEVERE WEATHER OPERATIONS THIS AFTERNOON AND
TONIGHT.

6