Tornado Warning 20, NWS Glasgow, MT

NORTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
225 PM MDT TUE JUL 24 2001

WATER VAPOR SHOWING ONE SHORTWAVE EXITING E MT THIS AFTERNOON...WHILE A
MORE VIGOROUS SYSTEM WAS DIGGING ACROSS BRITISH COLUMBIA. THIS SYSTEM
WILL BE THE NEXT AND PROBABLY THE BIGGEST WEATHER MAKER ACROSS NE MT
THROUGH THIS FORECAST CYCLE.

SATELLITE AND SFC OBSERVATIONS WERE SHOWING A COLD FRONT GETTING ITS
ACT TOGETHER OVER S ALBERTA WITH LOW PRESSURE DRIFTING E ACROSS S
ALBERTA. THE ETA AND AVN SEEM TO HAVE A GOOD HANDLE ON THE CURRENT
SITUATION AS IT DRAGS THIS SYSTEM E TONIGHT...BRINGING AN AREA OF
THUNDERSTORMS TO THE WESTERN ZONES THIS EVENING...THEN TO THE EASTERN
ZONES DURING THE OVERNIGHT. TIMING FOR THUNDERSTORMS FOR EASTERN ZONES
DIFFICULT HOWEVER...AS THERE CURRENTLY ARE STORMS FIRING DUE TO THE
EXITING DISTURBANCE.

THE FRONT STALLS OVER THE EASTERN ZONES WEDNESDAY...ALLOWING
FOR A CHANCE OF THUNDERSTORMS. SPC HIGHLIGHTS A SLIGHT CHANCE OF SEVERE
STORMS ACROSS A GOOD PORTION OF THIS AREA. WILL HOLD OFF ON MENTIONING
SEVERE POTENTIAL.

ON THURSDAY...THE UPPER FLOW BEGINS TO VEER AS A WEAK DISTURBANCE
DROPS INTO THE TROF OVER W MT. LIKE WED...BEST CHANCE OF STORMS WILL BE
OVER THE E ZONES.  JAMBA

EXTENDED...MODELS AGREE ON GENERAL PATTERN FOR DAYS 3 THROUGH 7.
WILL GO WITH AVN/MRF SINCE AVN MOST CLOSELY RESEMBLES ETA IN SHORT
TERM. MAIN CHG TO FORECAST WILL BE TO INTRODUCE TSTORMS INTO FCST
FOR SATURDAY. FRI SHOULD STAY DRY WITH WEAK RIDGING BETWEEN EXITING
SYSTEM AND PAC NW TROF. PACNW TROF SWINGS IN JUST AT THE WRONG TIME
(SAT PM) WITH A LOT OF INSTABILITY SO TS A GOOD BET WITH POSSIBLE
SVR WX EPISODE SAT EVE/NGT. PATTERN FOR SUN-TUE LOOKS TO BE ONE OF
RIDGE BLDG OFF WEST COAST WITH LONG WAVE TROF MOVING INLAND. WILL
KEEP UNSETTLED WX FOR SUN-TUE.        WRIGHT

KGGW 057/083 055/084 057/087 057/089 056/084 055/083 054/082
      BBBTTTT  765222/9526<333
KGDV 057/081 056/083 057/086 056/088 057/082 055/083 054/079
      BBBTTTT  764323/9526333