Damaging Wind in Montana, July 20, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
310 PM MDT FRI JUL 20 2012

.SHORT TERM...VALID FOR SAT AND SUN...

UPPER LEVEL RIDGE AXIS OVER THE WESTERN DAKOTAS IS BEING BROKEN
DOWN BY ENERGY MOVING THROUGH THE PACIFIC NORTHWEST THIS AFTERNOON.
SUBTROPICAL MONSOONAL MOISTURE FETCH IS OVER MOST OF THE FORECAST
AREA AT 1 PM WITH LIGHT SHOWER ACTIVITY NOTED ON RADAR EAST OF A
PRYOR TO HYSHAM LINE. AS THE AFTERNOON PROGRESSES WILL SEE DRIER
AIR WORK INTO WESTERN ZONES ALOFT SHIFTING CLOUDS AND BETTER
PRECIPITATION CHANCES EASTWARD. LEFT IN LOW POPS FOR WESTERN ZONES
THIS EVENING AS LATE AFTERNOON HEATING SHOULD BE ENOUGH TO
GENERATE A FEW THUNDERSTORMS. BEST CHANCES FOR PRECIPITATION
TONIGHT WILL BE EAST OF A MILES CITY TO BROADUS LINE WITH MOST
MODELS PUTTING DOWN A BROAD TENTH OF AN INCH OF RAIN THIS EVENING.
CHANCES FOR SEVERE THUNDERSTORMS LOOK VERY MARGINAL AT THIS POINT
GIVEN CURRENT TEMPERATURES AND CLOUD COVER SO LEFT MENTION OUT OF
THE FORECAST FOR NOW...BUT WILL CONTINUE TO MONITOR THE SITUATION
THROUGH THIS EVENING. VERY WEAK COLD FRONT/DRY AIR INTRUSION WILL
PUSH INTO PARK COUNTY LATE THIS EVENING AND SLOWLY WORK EASTWARD
THROUGH EARLY SATURDAY BEFORE STALLING OUT AROUND ROSEBUD COUNTY.
HARD TO SEE ANY SUBSTANTIVE IMPACTS FROM THIS FEATURE OTHER THAN A
WIND SHIFT AND SLIGHTLY DRIER LOW LEVEL AIRMASS.

FLOW ALOFT ON SATURDAY BECOMES FAIRLY ZONAL WHICH SHOULD BRING
PLENTY OF SUN AND DOWNSLOPE WARMING TO THE AREA. BUMPED TEMPERATURES
UP A BIT GIVEN THE THESE FACTORS ALONG WITH DRIER AIRMASS.
MONSOONAL MOISTURE DOES BUMP BACK NORTH INTO SOUTHERN ZONES BY
LATE IN THE DAY FOR JUST A SLIGHT CHANCE OF THUNDERSTORMS ACROSS
THE SOUTHERN TIER OF ZONES.

SYSTEM MOVING TOWARD THE WEST COAST WILL BACK UPPER FLOW TO THE
SOUTHWEST ALLOWING WARMER AIR AND MORE MONSOONAL MOISTURE TO MOVE
INTO THE AREA. TEMPERATURES WILL BE NEAR 100 DEGREES ACROSS MUCH
OF THE FORECAST AREA SUNDAY AFTERNOON. HOWEVER BETTER MOISTURE
PROFILES SUGGEST MORE WIDESPREAD CONVECTION...ESPECIALLY BY
SUNDAY EVENING. CHAMBERS

.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...

SOUTHWEST UPPER FLOW CONTINUES MONDAY BETWEEN HIGH PRESSURE
ACROSS THE PLAINS AND AN APPROACHING UPPER LOW IN THE PACIFIC
NORTHWEST. DISTURBANCES IN THE FLOW ALONG WITH AN APPROACHING COLD
FRONT WILL BE ENOUGH FOR A MENTION OF ISOLATED STORMS MONDAY INTO
MONDAY NIGHT. WOULD EXPECT THE BEST CHANCE OF STORMS TO BE OVER
THE MOUNTAINS AND ACROSS THE EAST...WHERE THE CAP WILL BE WEAKER
WITH 700 MB TEMPS GENERALLY 14C OR LESS. PACIFIC NORTHWEST UPPER
LOW IS EXPECTED TO TRACK OFF TO OUR NORTH TUESDAY THROUGH
WEDNESDAY WITH THE COLD FRONTAL PASSAGE LATE MONDAY INTO TUESDAY.
MONDAY SHOULD BE THE WARMEST DAY OF NEXT WEEK IN A PREFRONTAL
ENVIRONMENT. INCREASED SOUTHEAST WINDS OVER EASTERN MONTANA ARE
EXPECTED AHEAD OF THE FRONT WITH GUSTY NORTHWEST WINDS BEHIND IT
MONDAY NIGHT INTO TUESDAY LEADING TO THE POTENTIAL FOR DANGEROUS
FIRE WEATHER. TUESDAY WILL BE SLIGHTLY COOLER...BUT WILL STILL BE
QUITE WARM WITH HIGHS IN THE UPPER 80S TO MID 90S.

ANOTHER WEAK COLD FRONT OR SURFACE TROUGH LOOKS TO MOVE THROUGH
THE REGION WEDNESDAY...BRINGING A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS TO EASTERN PORTIONS OF THE CWA. UPPER LEVEL RIDGING
BUILDS BACK INTO THE AREA THURSDAY INTO FRIDAY. TEMPS WILL WARM
BACK UP INTO THE MID TO UPPER 90S...WHILE A FEW LOCATIONS MAY
REACH 100. SHORTWAVE ENERGY ROUNDING THE RIDGE MAY ENHANCE THE
POTENTIAL FOR SHOWERS AND THUNDERSTORMS LATE THURSDAY AND FRIDAY
OVER THE WESTERN MOUNTAINS...AND POSSIBLY FAR EASTERN ZONES...BUT
SUBSIDENCE/CAPPING SHOULD KEEP CONVECTION TO A MINIMUM ELSEWHERE.
STC

&&

.AVIATION...

WIDELY SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS THE ENTIRE
AREA THROUGH THIS EVENING. THESE WILL MAINLY BE HIGH BASED AND
THUS VFR WILL PREVAIL...THOUGH LOCAL MVFR IS A POSSIBILITY NEAR
EITHER KMLS OR KBHK. IN ADDITION...ERRATIC WIND GUSTS CAN BE
EXPECTED NEAR ANY STORMS THAT DEVELOP. THUNDERSTORMS WILL
DISSIPATE ACROSS THE WEST LATE THIS EVENING...BUT MAY LINGER INTO
LATE TONIGHT EAST OF A KMLS TO BROADUS LINE. MORE WIDELY SCATTERED
THUNDERSTORMS MAY IMPACT ALL FOUR TERMINALS SATURDAY AFTERNOON.
STC

&&

.PRELIMINARY POINT TEMP/POPS...

    SAT     SUN     MON     TUE     WED     THU     FRI
-----------------------------------------------------------
BIL 067/096 066/097 067/099 064/092 061/092 061/095 063/095
    22/T    22/T    22/T    20/U    10/U    00/U    11/U
LVM 055/093 055/092 056/096 054/091 054/091 052/093 054/092
    22/T    22/T    32/T    20/U    01/U    11/U    21/U
HDN 063/098 063/100 065/101 065/096 061/095 062/098 064/098
    22/T    22/T    22/T    21/U    11/U    00/U    11/U
MLS 071/101 070/100 072/104 069/095 064/094 064/098 066/098
    32/T    11/U    22/T    21/B    11/U    10/U    11/U
4BQ 065/098 064/098 067/100 068/094 061/094 063/098 065/097
    32/T    22/T    22/T    31/B    11/U    10/U    11/U
BHK 065/098 065/098 067/097 067/093 064/090 061/094 063/093
    32/T    22/T    22/T    32/T    22/T    11/U    11/U
SHR 061/096 060/096 061/098 062/093 058/093 057/096 059/095
    32/T    22/T    31/B    21/B    11/U    11/U    11/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.

&&

WEATHER.GOV/BILLINGS