Flash Flood Warning 2, NWS Billings, MT

SOUTH CENTRAL AND SOUTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
228 PM MDT MON AUG 5 2002

.SHORT TERM...VALID FOR TUE...WED...THU...

LARGE TROUGH OFF THE PAC NW COAST WILL PROVIDE A MOIST SOUTHWEST FLOW
ALOFT ACROSS THE FORECAST AREA. SOME SHORT WAVES WILL BE EMBEDDED WITHIN
THIS FLOW AND THIS WILL CONTINUE THROUGH WED. AS IS THE CASE WITH THIS
PATTERN...TIMING OF WAVES IS DIFFICULT. BEST CHANCES FOR CONVECTION WILL
BE DURING THE LATE AFTERNOON HOURS INTO THE EARLY EVENING AND CONTINUING
INTO THE NIGHT TIME HOURS ACROSS THE FAR EAST. TROUGH WILL REMAIN TO
THE WEST OF THE AREA THROUGH THE PERIOD WITH THE STRONGEST JET ENERGY
STAYING TO OUR NORTHWEST.

TONIGHT...THUNDERSTORMS IN THE WEST MAY BE SEVERE THIS EVENING. SPC
PLACES THE WESTERN HALF OF OUR AREA IN SLIGHT RISK FOR LATER THIS
AFTERNOON AND EVENING WITH OUR EXTREME NORTHWEST COUNTIES IN MODERATE
RISK. BEST CAPES THIS EVENING WILL BE OVER THE CENTRAL ZONES WHERE
VALUES WILL BE AROUND 1600J/KG. HOWEVER...700MB TEMPS ARE AROUND 14C
WITH BUFKIT SOUNDINGS SHOWING A CAP THROUGH MUCH OF THE EVENING.
PERSISTENT CLOUD COVER ACROSS MOST OF THE AREA MAY PLAY A ROLE IN
INHIBITING SEVERE STORMS. BEST CHANCES FOR SEVERE STORMS WILL BE IN THE
WESTERN AND CENTRAL ZONES. WILL MAKE THE DECISION ON MENTIONING OF
SEVERE WORDING IN THIS EVENINGS FORECAST LATER THIS AFTERNOON.

TUE & WED...SOUTHWEST FLOW CONTINUES WITH EMBEDDED SHORT WAVES. TUESDAY
SHOULD BE DRY WITH JUST A SLIGHT CHANCE OF A THUNDERSTORM OVER THE SW
MOUNTAINS BY EVENING. WILL NOT PLACE POPS IN THE FORECAST UNTIL TUES
NIGHT. ANOTHER WAVE WILL MOVE OVER THE AREA TUES NIGHT AND WED BRINGING
A BETTER CHANCE FOR THUNDERSTORMS. THE BEST CHANCES FOR STRONGER
STORMS WILL BE ACROSS THE SOUTHEAST WHERE INSTABILITIES WILL BE THE
GREATEST.

HAVE LOWERED TEMPS SLIGHTLY FOR TUESDAY BUT THEY WILL STILL BE VERY
WARM. READINGS WILL BE A FEW DEGREES COOLER FOR WED AS THERE WILL BE
MORE CLOUD COVER.  HOOLEY

THU...UPPER TROUGH PROGGED TO SWING INTO THE AREA THURSDAY BEHIND COLD
FRONTAL PASSAGE WEDNESDAY NIGHT. SCATTERED CONVECTION LOOKS IN LINE
THURSDAY AND THURSDAY NIGHT. WILL PAINT THE HIGHER SCATTERED POPS OVER
THE WEST...AND SHIFT IT OVER TO THE EAST THROUGH THE NIGHT. FRONTAL
PASSAGE ON WEDNESDAY NIGHT WILL SET UP UPSLOPE FLOW FOR THURSDAY. THIS
COMBINED WITH ADDED CLOUDS WILL KEEP TEMPERATURES DOWN. HUMPHREY

.LONG TERM...VALID FOR FRI...SAT...SUN...MON...
SOME CONSISTENCY IN THE EXTENDED MODEL SOLUTION IN THE FIRST HALF OF
THE PACKAGE...WITH DIFFERENCES DAYS 6 AND 7. UPPER TROUGH WILL SLIDE
THROUGH THE EASTERN HALF OF MONTANA FRIDAY. THE MODELS HAVE MOVED THIS
FEATURE QUICKER NOW AS THE UPPER LOW DOES NOT TOTALLY CLOSE OFF UNTIL
FRIDAY AFTERNOON OVER NORTHEAST WYOMING. THE CHANCE OF PRECIPITATION
NOW LOOKS A LITTLE LESS FOR FRIDAY THAN YESTERDAY...BUT WILL LEAVE
CHANCE POPS IN FRIDAY UNTIL THE SPEED OF THE TROUGH MOVEMENT BECOMES
MORE CLEAR. MESO RIDGE TO MOVE IN SATURDAY. THE FLOW FLATTENS SUNDAY
AND MONDAY WITH NEXT UPSTREAM WAVE DRIVING INTO SOUTHWEST CANADA. THE
ECMWF IS SLOWER WITH THIS SYSTEM AND IS THE ODD MODEL OUT HERE AS THE
UKMET AND EXT-AVN SWING IT INTO THE STATE SUNDAY. THE EXT-AVN BRINGS A
STRONG COLD FRONT ACROSS THE FORECAST AREA MONDAY EVENING. THE UPPER
TROUGH AXIS IS PROGGED TO EXIT THE STATE MONDAY AFTERNOON. WILL PUT
THE CHANCE OF CONVECTION MONDAY NIGHT AND TUESDAY. WARMING AHEAD OF THE
BOUNDARY SATURDAY AND SUNDAY IN DOWNSLOPE FLOW WITH STRONG COOLING
BEHIND IT. HUMPHREY

    TUE     WED     THU     FRI     SAT     SUN     MON
-----------------------------------------------------------
BIL 059/089 055/084 059/077 051/082 051/086 055/089 055/075
    30/B    23/T    44/T    43/T    00/U    00/U    33/T
LVM 052/083 050/082 050/074 047/080 047/084 051/087 051/073
    30/B    23/T    44/T    43/T    00/U    00/U    33/T
HDN 057/090 053/086 057/078 049/084 049/088 053/091 053/077
    30/B    23/T    44/T    43/T    00/U    00/U    33/T
MLS 065/090 058/088 064/079 052/084 052/088 056/091 056/077
    30/B    23/T    33/T    43/T    00/U    00/U    33/T
4BQ 064/091 057/089 063/080 053/083 053/087 057/090 057/076
    30/G    23/T    33/T    43/T    00/U    00/U    33/T
BHK 063/088 056/086 061/078 051/082 051/086 055/089 055/075
    30/B    23/T    33/T    43/T    00/U    00/U    33/T
SHR 058/089 054/086 056/076 047/080 047/084 051/087 051/073
    30/B    23/T    33/T    43/T    00/U    00/U    33/T

.BYZ...
MT...NONE.
WY...NONE.