Tornado Warning 1, NWS Glasgow, MT

NORTHEAST MONTANA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
250 PM MDT SUN JUN 20 1999

18Z SURFACE ANALYSIS INDICATED A COLD FRONT EAST OF A GGW-JDN-BIL LINE
WITH A WEAK SURFACE LOW IN SOUTHEAST MONTANA. DEWPOINTS REMAIN IN
THE MID 60S AHEAD OF THE FRONT IN LOW LEVEL UPSLOPE FLOW. AS A MID
LEVEL SHORTWAVE MOVES THROUGH SOUTH CENTRAL MONTANA THIS AFTERNOON
EXPECT CONVECTION TO DEVELOP ALONG AND AHEAD OF THE SURFACE COLD
FRONT WHERE SURFACE BASED LIS RANGE FROM -6 TO -8 WITH CAPES AOA
2000 J/KG. MAIN CONCERN OUT EAST TODAY WILL BE HAIL AND HEAVY RAIN.
PRECIPITABLE WATER VALUES ARE AGAIN AROUND AN INCH. WILL CONTINUE TO
KEEP THE SOUTHEAST ZONES IN A MENTION OF SEVERE THUNDERSTORMS FOR
TONIGHT.

A STRONG UPPER LEVEL JET OFF THE WEST COAST WILL DIG ALONG THE
BACKSIDE OF THE PACIFIC COAST TROUGH. MODELS ARE A LITTLE FAST WITH
THIS FEATURE MOVING EAST TOMORROW. DIGGING JET WILL ALLOW THE TROUGH
TO RETAIN A SLIGHTLY NEGATIVE TILT...ALLOWING THE THERMAL AND UPPER
LEVEL RIDGE TO BUILD OVER EASTERN MONTANA MONDAY. THE RESULT WILL BE WARM
TEMPERATURES ACORSS THE EAST TOMORROW. LEE CYCLOGENSIS WILL OCCUR IN
REPONSE TO AN UPPER LEVEL JET STREAK MOVING OVER THE AREA. EASTERN
MONTANA IS FORECAST TO BE IN THE RIGHT REAR QUADRANT BY 00Z. AREAS
ON THE EAST SIDE OF THE TROUGH WILL SEE A RETURN OF MOIST
SOUTHEASTERLY LOW LEVEL FLOW. BETTER UPPER LEVEL DYNAMICS AND
INCREASING LAPSE RATES WILL AGAIN LEAD TO ANOTHER ROUND OF AFTERNOON
CONVECTION...SO WILL MENTION THE CHANCE FOR SEVERE IN THE EASTERN
AND SOUTHERN ZONES. COOLER WITH SCATTERED SHOWERS TUESDAY AS THE
TROUGH AND SURFACE COLD FRONT MOVE THROUGH THE AREA.

GGW 2233 056/088/056/074
GDV 3243 064/090/061/076

CCF
GGW TB 056/088 056/074 053 99223