Severe Thunderstorm Warning 71, NWS Glasgow, MT

NORTHEAST MONTANA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
205 PM MDT WED JUL 5 2000

...SEVERE WEATHER THREAT FOR THE AREA TONIGHT AND THURSDAY...

UNSEASONABLY DEEP UPR TROF ALONG WEST COAST TO PERSIST THROUGH AT
LEAST THE NEXT SEVERAL DAYS. S/WS EJECTING OUT OF TROF ACRS MT WILL
PROVIDE TRIGGERS FOR CONVECTION.

FOR TODAY...FLOW AHEAD OF CLOSED UPR LOW IN NRN CA BACKING ACRS
INTER-MOUNTAIN WEST. ATTM DIFFICULT TO PICK OUT ANY INDIVIDUAL FTR
TO TRIGGER CONV ON SAT PIXS...BUT SPEED MAX PROGGED TO MOVE THRU
CNTRL MT BY LATE EVENING INTO TONIGHT. LEE CYCLOGENESIS OVER SE MT
TO DEVELOPING MOIST LOW LEVEL ELY FLOW OVER MOST OF CWA...ALONG WITH
SFC HEATING DESTABILIZING AIR MASS. GOES SOUNDER AT 18Z INDICATING
CAPES CLIMBING OVER 1000 J/KG ATTM. EXPECT CAPE TO CLIMB OVER 2000
J/KG OVER SRN CWA BY LATE AFTERNOON.

CONVECTION SHOULD DEVELOP OVER MTNS LATE THIS AFTERNOON AND SHOULD
RAPIDLY INTENSIFY OVR THE PLAINS. STG CONV FEEDBACK SIGNATURE ON
MESOETA/ETA INDICATING MCS DEVELOPMENT THIS EVENING...MOVING SLOWLY
ACRSS CWA INTO THE OVERNIGHT. THIS LOOKS REASONBLE WITH THETA-E
RIDGE AND DEVELOPING ELY LOW LEVEL JET CONVERGING OVER SRN CWA THIS
EVENING. TIMING OF SHORTWAVE INDICATES TODAYS CONVECTION WILL
PROBABLY BE LATER THAN YESTERDAYS OVER NEMONT. WITH SATURATED
CONDITIONS ACROSS ERN AND NRN CWA WILL CONSIDER FLASH FLOOD WATCH
FOR TONIGHT. CRNT SPS HIGHLIGHTS CONVECTIVE POTENTIAL FOR TONIGHT.

THURSDAY LOOKS TO BE ANOTHER VERY ACTIVE THUNDERSTORM DAY. SWLY FLOW
INDUCED SFC LOW IN SE MONT ALONG WITH SFC CONVERGENCE...STG ELY
FLOW...MOIST LOW LEVEL ATMOSPHERE...AND AN UPR LVL TRIGGER ALL SPELL
TROUBLE.  ETA INDICATED CAPES APCH 4400 J/KG OVR EXTRM NEMONT AND
LIS OF -13 WITH A NICELY SHEARED WIND PROFILE. QUESTION AT THIS
POINT IS TIMING. S/W AND SFC LOW MAY MOVE E OF CWA EARLY
ENOUGH...MID AFTERNOON...FOR THE SEVERE CONVECTION TO MOVE INTO ND
FAIRLY RAPIDLY. DESPITE THIS...ETA AGAIN INDICATING POTENTIAL TSTM
COMPLEX TO FORM OVER SWRN CWA BY EVNG TO TRACK SRN ZONES INTO ND BY
06Z.

AVN/ETA INDICATING QUIETER CONDS ON FRIDAY WITH DRIER WITH A MINOR
RIDGE ALOFT AND DRIER WESTRLY FLOW IN THE LOW LEVELS. PETRESCU

EXTENDED...MODELS IN GUD AGREEMENT INTO DAY THREE AND FOUR WITH
UPPER TROF OVER PAC COAST KEEPING NEMONT IN MOIST UNSTABLE SW FLOW.
SOUTHWEST FLOW CONTINUES WITH CHANGE IN THE PATTERN BY THE END OF
THE EXTENDED. WILL KEEP TEMPS ON THE WARM SIDE AND THE CONTINUING
CHANCE FOR THUNDERSTORMS. TEMPS MAY BE A TAD COOLER ON MONDAY. KPB

GGW TBTTT 059/085 056/085 058/090 058/086 055/085 916761/75366
GDV TBTTT 061/088 058/085 059/089 059/087 057/087 916771/75366