Severe Thunderstorm Warning 123, NWS Great Falls, MT

SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
300 PM MDT WED AUG 21 2002

.SHORT TERM...UNSETTLED WEATHER PATTERN TO CONTINUE INTO THIS
WEEKEND. UPPER LOW WILL MEANDER AROUND OVER THE PAC NW THROUGH FRI.
ON SAT AVN OPENS THE CLOSED LOW AND MOVES A VERY NEGATIVELY TILTED
UPPER TROUGH THROUGH THE FORECAST AREA. PRESSURE GRADIENTS WILL
CONTINUE TO BE WEAK THROUGH THE PERIOD SO EXPECT WINDS TO BE FOR THE
MOST PART LESS THAN 10 MPH. FOR TONIGHT MODELS HAVE A SHORTWAVE
MOVING N THROUGH THE AREA. AS MENTIONED IN THE MORNING DISCUSSION...
INGREDIENTS ARE IN PLACE FOR THE POTENTIAL OF ISOLATED SEVERE STORMS
INTO THIS EVENING FROM CENTRAL MT S. FOR THU AIRMASS IS FORECAST TO
BE GENERALLY LESS UNSTABLE OVER THE AREA. SHORTWAVES...IF THERE ARE
ANY...SHOULD ONLY AFFECT THE FAR ERN ZONES. WILL GO DRY WEST AND
MENTION SLIGHT CHANCE TO CHANCE POPS FARTHER E WHERE MODELS FORECAST
BETTER INSTABILITY. ON FRI MODELS INDICATE MORE SHORTWAVE ACTIVITY
AND HAVE AIRMASS MORE UNSTABLE. WILL THEREFORE GO WITH SLIGHT CHANCE
TO CHANCE POPS FOR THE ENTIRE AREA. ON SAT WITH AIRMASS AGAIN
FORECAST TO BE UNSTABLE AND THE POSSIBILITY OF AN UPPER TROUGH MOVING
INTO THE AREA CONTINUED THE FORECAST OF SLIGHT CHANCE TO CHANCE POPS.
WITH NO MAJOR CHANGE IN AIRMASS FORESEEN WILL CHANGE HIGHS AND LOWS
LITTLE FROM THU THROUGH SAT. BLANK

.EXTENDED...MRF AND ECMWF IN A LITTLE BETTER AGREEMENT TODAY THOUGH
THE ECMWF REMAINS PROGRESSIVE WITH THE PATTERN. UPPER TROF REMAINS
ACROSS THE PACIFIC NORTHWEST SUNDAY WITH MOIST AND UNSTABLE
SOUTHWEST FLOW ALOFT OVER THE AREA. TROF AXIS MOVES ACROSS THE AREA
MONDAY FOR CONTINUED UNSETTLED CONDITIONS. UPPER RIDGE BEGINS TO
BUILD OVER THE PACIFIC NORTHWEST TUESDAY WITH NORTHWEST FLOW ALOFT.
WILL MENTION LOW POPS FOR INSTABILITY SHOWERS. RIDGE BUILDS OVER
THE AREA WEDNESDAY FOR DRY AND WARMER CONDITIONS. TEMPERATURES
SHOULD REMAIN AT OR SLIGHTLY ABOVE SEASONAL NORMS.

.CCF NUMBERS
GTF BB 050/078 052/078 052 04512
    ETTTB 080/052 084/052 082/052 083/052 085 33333332221
CTB BE 050/075 048/075 050 04511
    ETTTB 077/050 083/050 082/050 083/050 084 22223322221
HLN BE 047/079 051/079 052 04611
    BTTTB 078/052 086/052 085/052 085/052 086 33223333321
BZN BE 042/079 046/079 046 04323
    BTTTB 078/045 084/045 082/045 082/045 084 33323333321
WEY BE 035/072 039/072 037 04223
    BTTTB 072/035 078/035 076/035 076/035 077 33323333321
DLN BE 042/077 045/077 044 04411
    BTTTB 077/045 084/045 083/045 083/045 084 23223222221
HVR BB 052/083 055/084 055 04212
    ETTTB 085/053 090/053 086/053 086/053 087 23323222221
LWT BB 048/078 052/078 050 04424
    ETTTB 079/050 084/050 083/050 083/050 084 33423333321=

.TFX...FLASH FLOOD WATCH FOR THE CAVE GULCH BURN AREA FROM 3 PM
       UNTIL 9 PM THIS EVENING.

LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
634 PM MDT WED AUG 21 2002

TIME(MDT)  .....EVENT  LOCATION..... ST   ...EVENT/REMARKS...........
           .....COUNTY LOCATION.....

0505 PM    7 W DILLON                MT   0.50 INCH HAIL
08/21/02   BEAVERHEAD                     ONE HALF INCH DIAMETER HAIL
                                          REPORTED BY SPOTTER.

0520 PM    MARYSVILLE                MT   0.50 INCH HAIL
08/21/02   LEWIS  AND  CLARK              ONE HALF INCH DIAMETER HAIL
                                          REPORTED BY SPOTTER.

0530 PM    3 N GEYSER                MT   0.25 INCH HAIL
08/21/02   JUDITH  BASIN                  LOTS OF PEA SIZED HAIL FELL
                                          AND FORMED DRIFTS UP TO 3
                                          INCHES DEEP...REPORTED BY
                                          SPOTTER.

0530 PM    GEYSER                    MT   0.25 INCH HAIL
08/21/02   JUDITH  BASIN                  LOTS OF PEA SIZED HAIL FELL
                                          AND FORMED DRIFTS OF 8 TO
                                          10 INCHES DEEP...REPORTED
                                          BY SPOTTER. 2.8 INCHES OF
                                          RAIN ALSO FELL IN 20
                                          MINUTES.

0535 PM    DILLON                    MT   0.88 INCH HAIL
08/21/02   BEAVERHEAD                     NICKEL SIZED HAIL REPORTED
                                          BY SPOTTER IN SOUTHEASTERN
                                          PORTION OF DILLON.

0545 PM    3 N DILLON                MT   0.50 INCH HAIL
08/21/02   BEAVERHEAD                     ONE HALF INCH DIAMETER HAIL
                                          WITH 0.16 INCHES OF
                                          RAINFALL REPORTED BY
                                          SPOTTER.

0605 PM    GRASSRANGE                MT   0.50 INCH HAIL
08/21/02   FERGUS                         ONE HALF INCH DIAMETER HAIL
                                          REPORTED BY SPOTTER.

0605 PM    SHERIDAN                  MT   0.50 INCH HAIL
08/21/02   MADISON                        ONE HALF INCH DIAMETER HAIL
                                          REPORTED BY SPOTTER.