490 
FXUS65 KBYZ 231955
AFDBIL

SOUTH CENTRAL AND SOUTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
155 PM MDT FRI JUN 23 2000

.SAT AND SUN...

BOTH THE AVN AND ETA APPEAR TO BE UNDERESTIMATING THE STRENGTH OF THE
SHORT WAVE OFF THE PACIFIC NORTHWEST ACCORDING TO SATELLITE DERIVED
WINDS COMPARED TO MODEL DEPICTION. EVIDENTLY SOME DATA DID NOT MAKE IT
INTO THE MODELS. HENCE...CONFIDENCE IN THE SCENARIO PRESENTED IS NOT
OVERLY HIGH.

PERSISTENT WEST TO NORTHWEST FLOW CONTINUES OVER THE COUNTY WARNING
AREA THIS SET. BEHAVIOR OF THE JET STREAKS RATHER IMPORTANT THIS TIME.
FOR TONIGHT...INSTABILITY LOOKS THE BEST FROM AROUND ROSEBUD COUNTY
AND EASTERN SHERIDAN COUNTY ON EAST. INVERTED TROUGH HAS DEEPENED A BIT.
CAPES ARE QUITE HIGH OVER THE AREA. SEVERE STORMS THIS EVENING ARE
POSSIBLE FROM AROUND ROSEBUD COUNTY EAST WITH GARDEN VARIETY TYPE
ELSEWHERE.

TOMORROW COULD BE ANOTHER INTERESTING DAY OVER THE EASTERN ZONES. AVN
SHOWS A JET STREAK PASSING THROUGH NORTHEAST MONTANA.  ETA SHOWS THIS
SAME FEATURE...BUT NOT AS STRONG. IN BOTH CASES...THE EASTERN ZONES
WILL BE RIGHT REARED...GIVING ANOTHER CHANCE FOR THUNDERSTORMS THERE.
SPC PLACES EXTREME SOUTHEAST MONTANA IN A SLIGHT RISK OF SEVERE STORMS
TOMORROW. THAT IS A POSSIBILITY...BUT WITH UNCERTAINTIES ON THE JET
INTERACTION...AM NOT GOING TO MENTION SEVERE STORMS AT THIS TIME FOR
SATURDAY.

WILL KEEP A MENTION OF THUNDERSTORMS DURING THE REMAINING PERIODS OVER
THE ENTIRE COUNTY WARNING AREA. GRANTED...STABILITY DOES INCREASE...AND
THINGS DRY UP SOME...BUT WITH WEST TO NORTHWEST FLOW OVER THE COUNTY
WARNING AREA STILL THERE...ALONG WITH A STRONGER SHORT WAVE PASSING
OVER THE AREA SUNDAY...ISOLATED THUNDERSTORMS...AT LEAST...REMAIN
A GOOD POSSIBILITY.

COOLER AIR DOES LOOK LIKE IT WORKS ITS WAY INTO THE AREA FOR SUNDAY.
THUS TEMPERATURES SHOULD BE COOLER THEN. CHB

.MON...TUE...AND WED...

ALL THREE MODELS SUGGEST WEST TO NORTHWEST FLOW CONTINUING OVER THE
COUNTY WARNING AREA THROUGH WEDNESDAY. UPPER LEVEL RIDGE APPROACHES
THE AREA WEDNESDAY WARMING THE TEMPERATURES UP A BIT. WHILE RIPPLES
UNDOUBTEDLY WILL BE PASSING THROUGH THIS FLOW...AM NOT LOOKING FOR
PRECIPITATION TO EXCEED CLIMATOLOGY. THUS... A MAINLY DRY
FORECAST SHOULD WORK FOR ALL THREE PERIODS. CHB

BIL BBBBB 055/081 051/072 051/080 052/079 053/084 523222 52
LVM BBBBB 048/076 045/073 046/077 049/077 051/082 522222 52
HDN BBBBB 053/083 049/074 049/082 050/081 051/086 523222 52
MLS TBBBB 057/082 053/076 052/082 053/079 053/082 524432 52
4BQ TBBBB 056/081 052/074 050/081 051/078 051/081 524322 52
BHK TBBBB 053/080 050/072 048/079 049/076 049/080 524432 52
SHR BBBBB 051/083 049/072 046/078 048/076 049/081 524222 52