AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
208 PM MDT SAT MAY 29 1999
A FLOOD WARNING REMAINS IN EFFECT FOR THE YELLOWSTONE RIVER AT
LIVINGSTON AND VICINITY.
GIST OF MODELS IS TO THINK WET. SATELLITE PICTURES INDICATE A FEW
DISTURBANCES MOVING THROUGH A MOIST SOUTHERLY FLOW. WITH DIGGING TROUGH
GOING ON WEST...THIS MOIST SOUTHERLY FLOW SHOULD CONTINUE FOR A WHILE.
CAPES OUT EAST AS OF 18Z AROUND 550 J/KG. NOT SO MUCH IN BILLINGS AREA.
AIRCRAFT SOUNDING ON A DESCENT TO BILLINGS AT 1840Z INDICATED AN
INVERSION FROM 813 MB TO 700 MB. THIS IS THE FRONTAL INVERSION AS WINDS
BENEATH THIS ARE NORTHEAST...WHILE ABOVE IT...WINDS ARE SOUTHWEST. WITH
CLOUD COVER OVER AREA...MAY NOT BREAK THIS INVERSION. RAINS THEN FROM
AROUND THE BILLINGS AREA SHOULD MAINLY BE STRATIFORM WITH ISOLATED
THUNDERSTORMS. OUT EAST...ESPECIALLY WHERE HEATING HAS TAKEN
PLACE...THUNDERSTORMS SHOULD TAKE OFF. CAPES SHOULD INCREASE TO ABOUT
1500 J/KG. STRONG SHEAR IS STILL PRESENT NEAR THE FRONTAL BOUNDARY
THERE. HAVE NOT CHANGED MIND ABOUT SEVERE STORMS THIS AFTERNOON AND
EVENING OVER ABOUT THE EAST HALF. LOCALLY HEAVY RAINS ALSO A GOOD BET
EAST DUE TO THE THUNDERSTORMS AND OVER MOUNTAINOUS AREAS DUE TO
OROGRAPHIC LIFT.
TEMPERATURES A BIT TRICKY DUE TO CLOUD COVER AND EXTENT OF RAIN. AS FOR
MENTIONING OF SNOW...FREEZING LEVELS DO NOT GET THAT LOW UNTIL SUNDAY
NIGHT...AND THEN ABOUT 6500 TO 7000 FEET. WHILE SNOW SHOULD BE
MENTIONED ABOVE THAT LEVEL...AM QUESTIONING WHAT KIND OF ACCUMULATION
THERE WOULD BE.
A GRADUAL SAGGING OF THE FRONTAL BOUNDARY SHOULD LESSEN THE
PRECIPITATION CHANCES ON MONDAY...BUT NOT ELIMINATE THEM. CHB
NORTHERN PORTION OF CURRENT TROUGHING PROGGED BY EXTENDED MODELS TO
SLIDE SOUTHWARD TO SW US BY TUESDAY BRINGING DRYER WESTERLY FLOW TO
AREA. THIS IS QUICKLY REPLACED BY ANOTHER AREA OF ENERGY DROPPING
SOUTHWARD INTO PACIFIC NORTHWEST BY WEDNESDAY FOR ANOTHER PERIOD OF
UNSETTLED WEATHER. TEMPS LOOK TO BE ABOUT NORMAL THEN TRENDING COOLER.
RASCH
BIL WE 047/060 042/065 048 529963
LVM .. 042/056 039/060 ... 529963
HDN .. 046/061 041/066 ... 529963
MLS .. 051/065 046/066 ... 528763
4BQ .. 049/063 044/064 ... 528763
BHK .. 048/061 042/063 ... 528763
SHR WE 046/061 040/062 043 528763
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