Severe Thunderstorm Warning 60, NWS Great Falls, MT

SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
245 PM MDT FRI JUN 20 2003

.DISCUSSION...

.TONIGHT THROUGH SUNDAY...CYCLONIC SW FLOW ALOFT WILL BE OVER THE
FORECAST AREA THROUGH LATE SATURDAY THEN TURN MORE WLY ON SUN. FLOW
IS ASSOCIATED WITH AN UPPER LOW OVER B.C. WHICH WINDS ITS WAY SLOWLY
E AND INTO WRN SASK BY LATE SUNDAY. A FEW SHORTWAVES WILL ROTATE
THROUGH THE FLOW DURING THE PERIOD. AT THE SURFACE PRETTY STRONG
DOWNSLOPE WILL BE OVER THE NRN ZONES WHILE LIGHTER DOWNSLOPE OR WEAK
UPSLOPE WILL BE OVER THE SRN ZONES. THIS PATTERN WILL CONTINUE
THROUGH THE PERIOD. MAIN BAND OF STRONGER TSTMS WILL BE NR OR E OF
FORECAST AREA BY 00Z SAT SO WILL DROP MENTION OF STRONGER STORMS
AFTER 6PM THIS EVE. WITH FAIRLY STRONG DOWNSLOPE OVER THE NRN ZONES
PRECIPITATION CHANCES WILL BE LOW LATE TONIGHT THROUGH SUN.
TIME/HEIGHT CROSS SECTIONS SHOW SINKING MOTION BUT THERE WILL BE
SOME WEAK INSTABILITY. WAS GOING TO GO DRY OVER THE PLAINS SAT THRU
SUN BUT WILL BEEF UP POPS FOR THE NRN ZONES FOR SUN TO LINE UP
BETTER WITH GGW. OVER THE SRN ZONES LOW LEVEL CONVERGENCE ALONG WITH
INSTABILITY COULD LEAD TO ISOLATED TSTMS SAT INTO SAT EVENING. OVER
THE ROCKY MOUNTAIN FRONT WINDS SHOULD STAY BELOW HIGH WIND CRITERIA
BUT THEY MAY GET CLOSE AT TIMES. THREAT LOOKS TINY ENOUGH NOT TO
ISSUE A WATCH. ALSO SNOW LEVELS MAY LOWER ENOUGH OVER THE ROCKY
MOUNTAIN FRONT FOR A LITTLE LIGHT SNOWFALL ABOVE 6500 FEET AT NIGHT.

MONDAY AND TUESDAY...UNSETTLED WEATHER TO CONTINUE THROUGH THE EARLY
PART OF NEXT WEEK. UPPER LEVEL LOW PRESSURE TO CROSS MONTANA LATE
MONDAY AND TUESDAY. AN AREA OF SURFACE LOW PRESSURE DEVELOPS IN
SOUTHWEST MONTANA ON MONDAY, AND WITH UPSLOPE CONDITIONS ACROSS THE
AREA, EXPECT THE BEST CHANCE FOR SHOWERS AND ISOLATED THUNDERSTORMS.
TEMPERATURES WILL REMAIN BELOW SEASONAL NORMS DURING THIS TIME. JCA

WEDNESDAY THROUGH FRIDAY...THE AIRMASS THEN CONTINUES TO DRY
WEDNESDAY THROUGH FRIDAY. TEMPS REMAIN BELOW NORMALS MONDAY THROUGH
WEDNESDAY...MOVING BACK NEAR NORMAL THURSDAY AND FRIDAY. ZELZER

.CCF NUMBERS
GTF BB 046/066 044/064 040 044-1
    EEBBB 066/042 065/044 070/046 071/049 076 12344333333
CTB NE 044/060 041/059 040 041-1
    EEBBB 062/042 064/042 069/045 069/047 071 22333332233
HLN BB 047/066 045/065 042 04311
    EEBBB 067/045 067/047 071/049 073/050 079 12344333322
BZN BB 044/065 039/064 039 04522
    EEBBB 064/042 067/043 071/045 070/046 077 -2444334422
WEY BB 038/058 031/058 035 04622
    BEBBB 060/038 059/036 060/037 063/040 065 12444333111
DLN BB 043/064 039/064 039 04322
    EWBBB 064/042 067/044 069/042 072/045 076 -2455333111
HVR BE 049/070 045/067 044 046-1
    BEBBB 067/046 069/047 076/049 075/051 080 22344333322
LWT BB 046/065 042/061 039 046--
    BEBBB 067/043 065/044 066/045 069/047 073 -2344334422

.TFX...SEVERE THUNDERSTORM WATCH CENTRAL AND NORTH CENTRAL THROUGH 8
       PM THIS FRI EVENING (ZONES 11/47/13/50/51
       HILL/BLAINE/CHOUTEAU/FERGUS/JUDITH BASIN)

MTZ008>015-044>055-210010-
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREAT FALLS MT
1200 PM MDT FRI JUN 20 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND SOUTHWEST MONTANA

.DAY ONE...TODAY

NO WATCHES, WARNINGS, OR ADVISORIES CURRENTLY IN EFFECT

A SEVERE THUNDERSTORM WATCH IS IN EFFECT UNTIL 8 PM MDT FOR MUCH OF
THE AREA. THUNDERSTORMS WILL BE CAPABLE OF PRODUCING WINDS TO 70 MPH
AND HAIL UP TO ONE INCH IN DIAMETER.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.