Severe Thunderstorm Warning 7, NWS Billings, MT

SOUTH CENTRAL AND SOUTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
157 PM MDT MON MAY 28 2001

.TUE AND WED...
NEITHER THE ETA NOR THE AVN MODEL EXACTLY MATCH UP WITH THE 18Z WATER
VAPOR IMAGERY. THE RELATIVE HUMIDITY FIELDS ARE SOMEWHAT BEHIND WHAT
THE IMAGERY REVEALS ALTHOUGH ETA SEEMS TO DO SOMEWHAT BETTER WITH
PLACEMENT OF THE UPPER AIR FEATURES. ETA HAS A SLIGHT EDGE WITH THE
SURFACE FEATURES OVER CANADA AT 18Z...BUT AVN DOES BETTER OVER AREAS
OF THE CONUS SOUTH OF MONTANA.

THE ESSENCE OF BOTH MODELS...HOWEVER...IS SIMILAR. THE UPPER RIDGE
MOVES EAST FOLLOWED BY A STRONG SURGE ALOFT CREATING NEAR ZONAL FLOW
OVER THE COUNTY WARNING AREA BY TUESDAY LATE AFTERNOON. VORT LOBES
MAKE THEIR WAY INTO THE COUNTY WARNING AREA TONIGHT INTO TUESDAY
BRINGING THE MUCH NEEDED RAIN TO THE AREA. ON THE SURFACE...A FRONTAL
SYSTEM PASSES THROUGH THE COUNTY WARNING AREA...EXITING THE EASTERN
ZONES LATE TUESDAY AFTERNOON. HIGH TEMPERATURES BEHIND THE SYSTEM WILL
BE SOMEWHAT COOLER THAN READINGS HAVE BEEN RECENTLY.

INDICATIONS ARE THAT SOME SUBSIDENCE MAY SHUT OFF THE PRECIPITATION
VERY SOON AFTER FRONTAL PASSAGE. AM NOT SO SURE THAT WAY. AMONG OTHER
THINGS...THE SYSTEMS HAVE BEEN SLOW MOVING AND THIS ONE DOES NOT LOOK
LIKE THE EXCEPTION. A VORT MAX IS AROUND THE EASTERN ZONES ON WEDNESDAY
AT 18Z ACCORDING TO BOTH MODELS...MORE SO WITH ETA THAN AVN. MOREOVER...
ETA HINTS AT POSSIBLE PRECIPITATION OVER THE BIG HORNS ON WEDNESDAY.
FOR NOW WILL GRADUALLY SLOW DOWN THE PRECIPITATION OVER THE EAST TO
WHERE THERE WILL BE JUST ISOLATED LINGERING MORNING SHOWERS OVER THE
EXTREME EAST THAT DAY.

GUIDANCE TEMPERATURES FOR TUESDAY...ESPECIALLY FOR FAN AND MAV IN SOME
INSTANCES...SEEM RATHER COLD. THINGS GET BETTER WEDNESDAY...BUT STILL
A BIT COOL...ESPECIALLY THE MAV SOLUTION. CHB

.THU...FRI...SAT...SUN...MON...

NORTHWEST FLOW ALOFT WILL CONTINUE ACROSS THE AREA THURSDAY...BRINGING
ISOLATED SHOWERS TO THE EAST AND COOL WEATHER AREA-WIDE.  UPPER LEVEL
RIDGE WILL BEGIN BUILDING IN THE WEST LATE THURSDAY AND MOVE SLOWLY
EAST THROUGH SATURDAY. RIDGE WILL BRING WARMING TEMPERATURES AND DRY
WEATHER TO THE WEST THURSDAY NIGHT AND FRIDAY AND TO THE EAST FRIDAY
AND FRIDAY NIGHT. SOUTHWEST FLOW WILL DEVELOP OVER THE AREA BY
SATURDAY...BRINGING A CHANCE OF SHOWERS TO THE AREA SATURDAY THROUGH
MONDAY. TEMPERATURES WILL BE IN A COOLING TREND SATURDAY AND SUNDAY.
MIDDENDORF

    TUE     WED     THU     FRI     SAT     SUN     MON
-----------------------------------------------------------
BIL 050/071 045/075 050/075 052/087 057/078 047/070 049/072
    62/W    00/B    20/U    02/B    23/T    33/T    32/B
LVM 048/067 040/072 043/075 045/085 050/075 042/067 043/070
    62/W    00/B    20/U    02/B    23/T    33/T    32/B
HDN 048/073 043/077 046/078 048/090 053/082 043/073 044/075
    63/W    20/B    20/U    02/B    23/T    33/T    32/B
MLS 055/074 045/075 047/072 052/090 055/089 050/075 049/075
    66/T    30/B    22/B    20/U    03/T    33/T    33/T
4BQ 054/073 044/074 044/070 050/088 053/087 048/074 047/073
    66/T    30/B    22/B    20/U    03/T    33/T    33/T
BHK 054/073 042/073 043/068 048/086 050/085 046/073 045/072
    66/T    42/W    22/B    20/U    03/T    33/T    33/T
SHR 051/070 044/073 043/075 045/087 050/083 042/072 043/070
    64/T    30/B    22/B    20/U    03/T    33/T    33/T