Severe Thunderstorm Warning 213, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
345 PM CDT SUN JUL 13 2003

...EASTWARD EXTENT OF CONVECTION TONIGHT AND CHCS EAST MONDAY
AFTN/EVE IN THE EAST ARE MAIN FORECAST CHALLENGES...

THUNDERSTORMS ARE ONCE AGAIN DEVELOPING OVER THE HIGH PLAINS OF
WYOMING AND COLORADO. COVERAGE AND FAVORABILITY MUCH BETTER THAN
LAST EVENING. HAVE KEPT POPS LOW DUE TO 1 DEGREE CAP OVER THE
WESTERN CWFA THIS EVENING. RICH BLOUNDARY LAYER MOISTURE AND STRONG
AFTN HEATING TO THE WEST AND NORTHWEST WILL COMBINED WITH FAVORABLE
DEEP LAYER SHER OF 35-40KTS TO HELP BREAK THIS CAP AS THE CONVECTION
TRIES TO MOVE EAST. A FEW STORMS SHOULD MOVE EAST ACROSS THE NORTH
OVERNIGHT ON NOSE OF 40KT H8 JET.

A PRE-FRONTAL TROF WILL SLIDE TO JUST EAST OF CWFA BY 18Z. WILL
FOLLOW A SLOWER TIMING OF VORT MAX MOVING THROUGH NWRN CWFA WITH
SLIGHT CHC BEGINNING EARLY AFTN AND ENDING LAT EVENING. TIMING OF
THIS FRONT FAVORS AREAS TO OUR EAST WHERE SCT POPS CAN BE JUSTIFIED.

WILL KEEP DRY TUES THROUGH FRIDAY DAYTIME. UPPER RIDGE WILL BUILD
INTO CENTRAL PLAINS AND KEEP ANY LOW CHCS TO OUR NORTH. WEDNESDAY
LOOKS TO BE THE HOTTEST DAY WHERE THERMAL RIDGE WILL FAVOR ERN
CO...NEBRASKA AND KANSAS. TEMPS NEAR 100 LIKELY IN OUR SOUTH.

EXTENDED DISCUSSION...FAVORING THE ECMWF...UPPER RIDGE CENTER SHOULD
REMAIN OVER ERN CO ON DAYS 4 AND 5 AS UPPER LOW CROSSES THE SOUTHERN
PROVINCES OF CANADA. POLAR VORTEX SHOULD PHASE WITH THE UPPER LOW TO
THE SOUTH TO FORM A LONGWAVE TROUGH SOUTHWARD THROUGH THE GREAT
LAKES ON DAY 6. THIS WILL DRIVE THE UPPER HIGH BACK INTO THE FOUR
CORNERS REGION AND PUT THE CNTRAL PLAINS REGION BACK INTO A NW FLOW
REGIME WITH COOLER TEMPERATURES ALOFT. THE CMC AND NOGAPS ARE IN
CLOSE AGREEMNET ON UPPER RIDGE DOMINATING REGION WITH A HOT AND DRY
EXTENDED. FEEL THE 00Z GFS IS FLATTENING AND WEAKENING THE UPPER
RIDGE TOO MUCH AND WILL TRIM BACK COVERAGE OF POPS FRIDAY NIGHT
THROUGH SATURDAY NIGHT TO MAINLY EVENING WEST AND OVERNIGHT NORTH
CENTRAL.

.LBF...NONE.

KAR

NEZ004>010-022>029-035>038-056>059-069>071-094-141000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORTH PLATTE NE
335 PM CDT SUN JUL 13 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND NORTH CENTRAL
NEBRASKA.

.DAY ONE...TODAY

MOISTURE AND AN UPPER LEVEL DISTURBANCE WILL INTERACT WITH A SURFACE
BOUNDARY ACROSS THE WESTERN PANHANDLE THIS AFTERNOON AND LEAD TO
THUNDERSTORM DEVELOPMENT. EAST OF THIS SURFACE BOUNDARY...ACROSS
WESTERN PORTIONS OF THE OUTLOOK AREA...STRONG HEATING...AND A RETURN
OF DEEPER MOISTURE HAS ALLOWED THE ATMOSPHERE TO BECOME MODERATELY
UNSTABLE. WARMING TEMPERATURES ALOFT WILL HELP TO INITIALLY INHIBIT
THUNDERSTORM DEVELOPMENT ACROSS THE WESTERN OUTLOOK AREA. HOWEVER IF
STORMS ARE ABLE TO SEPARATE FROM THE BOUNDARY TO THE WEST AND MOVE
INTO THE DEEPER MOISTURE...ISOLATED STORMS WILL HAVE THE POTENTIAL
TO RAPIDLY BECOME SEVERE. THE AREA OF GREATEST CONCERN WILL BE
ACROSS THE EASTERN PANHANDLE LATE THIS AFTERNOON...THEN MAINLY EAST
OF A LINE EXTENDING FROM HAYES CENTER IN HAYES COUNTY...TO AINSWORTH
IN BROWN COUNTY THROUGH LATE THIS EVENING.  THE MAIN THREATS WILL BE
DAMAGING WINDS AND LARGE HAIL.

THUNDERSTORM DEVELOPMENT WILL CONTINUE TO BE POSSIBLE OVERNIGHT
ACROSS AREAS NORTH IF HIGHWAY 2. THESE LATE NIGHT THUNDERSTORMS ARE
NOT EXPECTED TO REACH SEVERE LEVELS...ALTHOUGH SMALL HAIL AND WIND
GUSTS UP TO 35 MPH WILL BE POSSIBLE.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THE FRONTAL SYSTEM WILL PROGRESS SOUTHEAST INTO NEBRASKA ON MONDAY
WITH A SURFACE TROUGH MOVING THROUGH WESTERN NEBRASKA DURING THE
MORNING. THIS SURFACE TROUGH WILL MAINLY SERVE TO SWEEP MOISTURE
INTO EASTERN PORTIONS OF THE OUTLOOK AREA TOMORROW AFTERNOON...WITH
WESTERLY DOWNSLOPE WINDS BEHIND THE FEATURE HELPING TO DRY OUT THE
ATMOSPHERE. THE MAIN AREA OF CONCERN FOR POSSIBLE SEVERE
THUNDERSTORM DEVELOPMENT WILL BE...MAINLY EAST OF HIGHWAY 11 ACROSS
THE NORTHEAST PORTIONS OF THE OUTLOOK AREA. WARM MID LEVEL
TEMPERATURES WILL AGAIN INHIBIT THUNDERSTORM DEVELOPMENT UNTIL
TOMORROW AFTERNOON. THE MAIN THREATS WILL BE LARGE HAIL AND DAMAGING
WINDS GUSTS.

DRY WEATHER IS EXPECTED TUESDAY THROUGH THURSDAY...THEN ANOTHER
ROUND OF CONVECTION IS POSSIBLE FRIDAY AND SATURDAY AS THE NEXT
FRONTAL SYSTEM MOVES THROUGH THE PLAINS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY THROUGH SATURDAY.

13

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORTH PLATTE NE
0628 PM CDT SUN JUL 13 2003

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

0550 PM    22 NNW RUSHVILLE          SD   50 MPH TSTORM WIND
07/13/03   SHANNON                        EST WINDS BETWEEN 50 AND
                                          65 MPH

MB