Severe Thunderstorm Warning 355, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
939 PM CDT THU JUL 20 2000

PARAMETERS FOR A NOCTURNAL WIND EVENT APPEAR TO BE COMING TOGETHER
FOR PORTIONS OF THE FORECAST AREA LATER TONITE.  EVENING SFC ANALYS
IS SHOWING A MULTITUDE OF LEFT OVER OUTFLOW BOUNDARIES LEFT OVER
FROM LAST NITE/S AND TODAY/S CONVECTIVE ACTIVITY.  THE MOST
IMPORTANT OF SAID BOUNDARIES APPEARS TO LIE ROUGHLY ALONG THE
GAGE/WATONGA/OKLAHOMA CITY/ADA CORRIDOR WITH A STRONG 850 MB
BAROCLINIC ZONE ALONG AND JUST NORTH OF THE SFC BOUNDARY. STRONG TO
SEVERE CONVECTION IS ALREADY ONGOING STRONG ACROSS MUCH OF CENTRAL
AND WESTERN KS ATTM..ABOUT 3 HOURS EARLIER THAN LAST EVENING. RATHER
IMPRESSIVE 300 MB JET ENTRANCE REGION FOR JULY OVER KS WILL LIKELY
ENHANCE SRLY LLJ..AND EXPECT THIS ACTIVITY WILL BUILD SEWD INTO THE
DEVELOPING LLJ AXIS OVERNIGHT ALONG AND JUST NORTH OF THE
AFOREMENTIONED SFC BOUNDARY LYING NW TO SE ACROSS THE AREA.  MCS
WILL LIKELY BE ACCOMPANIED BY SVR WIND GUSTS AND POSSIBLY SOME HAIL
WITH THE STRONGEST STORMS..ESP OVER NRN OK. THIS IS SUPPORTED BY
EVIDENCE OF A DEVELOPING LOW LEVEL COLD POOL WITH MCS ATTM..AND
CONVECTION SLOWLY BECOMING ORIENTED PERPENDICULAR TO THE MID LEVEL
FLOW.

OTHER QUESTION IS HOW FAR SOUTH TO BRING THE MCS TOMORROW MORNING.
LATEST MCS PROPAGATION VECTOR FORECASTS FROM THE 00Z RUC WUD SUGGEST
THAT THE MCS WILL OBTAIN A GOOD SRLY DEVELOPMENT COMPONENT AFTER
MIDNIGHT..SO CARRYING POPS INTO SRN OK FRIDAY MORNING LOOKS GOOD.
HEAVY RAINFALL EVENT MAY SET UP INVOF RESIDUAL OUTFLOW BOUNDARY AS
STRONG 850 MB WAA/THETA ADVECTION PERSIST THRU THE MORNING.

UPDATED ZONES WERE ISSUED ABOUT AN HOUR AGO TO REFLECT THE ABOVE
THINKING.
 MILLER

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

OKZ004>048-050>052-TXZ083>090-210600-

THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
1137 PM CDT THU JUL 20 2000

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVERNIGHT TONIGHT
ACROSS MUCH OF NORTHERN OKLAHOMA...GENERALLY NORTH OF A LINE FROM
GAGE...TO WATONGA...TO OKLAHOMA CITY...TO SEMINOLE. THERE IS A
SLIGHT RISK OF SEVERE THUNDERSTORMS OVERNIGHT NORTH OF A LINE FROM
CHEYENNE TO ADA.

DISCUSSION...A LARGE COMPLEX OF SEVERE THUNDERSTORMS OVER SOUTHERN
KANSAS WILL MOVE RAPIDLY SOUTHEAST ACROSS MUCH OF NORTHERN OKLAHOMA
OVERNIGHT. THE PRIMARY THREAT FROM THESE THUNDERSTORMS WILL BE
DAMAGING WIND GUSTS FROM 60 TO 90 MPH.  A FEW REPORTS OF HAIL UP TO
THE SIZE OF QUARTERS ARE ALSO EXPECTED.

WIND SHEAR PARAMETERS ARE ALSO SUPPORTIVE OF SUPERCELLS...AND A FEW
SUPERCELLS MAY DEVELOP WITHIN THE LINE OF STORMS OR AHEAD OF IT.
THE POSSIBILITY OF A TORNADO OR TWO CANNOT BE RULED WITH ANY
SUPERCELLS THAT ARE ABLE TO DEVELOP.

EMERGENCY MANAGER AND STORM SPOTTER GROUP ACTIVATION WILL BE REQUIRED
ACROSS THE NORTHERN HALF OF OKLAHOMA OVERNIGHT.

 MILLER

OKZ004>048-050>052-TXZ083>090-210600-

THUNDERSTORM OUTLOOK...UPDATED..
NATIONAL WEATHER SERVICE NORMAN OK
1137 PM CDT THU JUL 20 2000

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVERNIGHT TONIGHT
ACROSS MUCH OF NORTHERN OKLAHOMA...GENERALLY NORTH OF A LINE FROM
GAGE...TO WATONGA...TO OKLAHOMA CITY...TO SEMINOLE. THERE IS A
SLIGHT RISK OF SEVERE THUNDERSTORMS OVERNIGHT NORTH OF A LINE FROM
CHEYENNE TO ADA.

DISCUSSION...A LARGE COMPLEX OF SEVERE THUNDERSTORMS OVER SOUTHERN
KANSAS WILL MOVE RAPIDLY SOUTHEAST ACROSS MUCH OF NORTHERN OKLAHOMA
OVERNIGHT. THE PRIMARY THREAT FROM THESE THUNDERSTORMS WILL BE
DAMAGING WIND GUSTS FROM 60 TO 90 MPH.  A FEW REPORTS OF HAIL UP TO
THE SIZE OF QUARTERS ARE ALSO EXPECTED.

WIND SHEAR PARAMETERS ARE ALSO SUPPORTIVE OF SUPERCELLS...AND A FEW
SUPERCELLS MAY DEVELOP WITHIN THE LINE OF STORMS OR AHEAD OF IT.
THE POSSIBILITY OF A TORNADO OR TWO CANNOT BE RULED OUT WITH ANY
SUPERCELLS THAT ARE ABLE TO DEVELOP.

EMERGENCY MANAGER AND STORM SPOTTER GROUP ACTIVATION WILL BE REQUIRED
ACROSS THE NORTHERN HALF OF OKLAHOMA OVERNIGHT.

 MILLER