Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 300252
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
852 PM MDT MON SEP 29 2014

.UPDATE...
LATEST MODEL INDICATORS SHOW LOTS OF FAVORABLE DYNAMIC PROCESSES
AFFECTING OUR FAR EAST/SOUTHEAST BY 600 AM TOMORROW MORNING AS
CLOSED UPPER LOW TRACKS ACROSS RAPID CITY VICINITY AND UP THROUGH
THE DAKOTAS. SO THE INHERITED CATEGORICAL POPS AND QPF LATE
TONIGHT AND TUESDAY FOR THIS AREA VERY LEGIT. THE REST OF OUR
FORECAST AREA WILL SEE MUCH LESS IN THE TERMS OF IMPACT. BT

FOR THIS EVENING...ADJUSTED POPS FOR THE EVENING IN EAST AS DOES
NOT LOOK LIKE MAIN AREAS OF PRECIP WILL REACH SE CORNER OF STATE
UNTIL AROUND/AFTER MIDNIGHT. HRRR A LITTLE MORE BULLISH ON QPF
OVER CUSTER AND POWDER RIVER SO PULLED HIGHER POPS WEST TO THESE
COUNTIES JUST A BIT FOR LATE TONIGHT. REST OF FORECAST LOOKS GOOD.
BT

&&

.SHORT TERM...VALID FOR TUE AND WED...

UPPER LOW CONTINUES TO WEAKEN AS IT LIFTS SLOWLY NEAR YELLOWSTONE
PARK. FOG/STRATUS FROM EARLIER TODAY IS ERODING AWAY SLOWLY WITH
DAYTIME MIXING AND AS WE NO LONGER HAVE STRONG UPSLOPE SFC WINDS.
VISIBLE SATELLITE IMAGERY SHOWS RAPID DEVELOPMENT OF CU OVER OUR
MOUNTAINS AND THIS SHOULD TRANSLATE TO ISOLATED-SCATTERED SHOWERS
ACROSS OUR WEST THROUGH AROUND SUNSET AS WE APPROACH CONVECTIVE
TEMPS IN THE LOW 60S UNDER COOL POOL ALOFT. THIS WILL NOT AMOUNT
TO MUCH...BUT WE MAY SEE A LIGHT SHOWER NEAR BILLINGS BY LATE
AFTERNOON. A FEW LIGHTNING STRIKES ALSO POSSIBLE OVER THE
BEARTOOTH ABSAROKAS.

BIGGER CONCERN EVOLVES AROUND STRONG ENERGY COMING OUT OF THE
SOUTHERN ROCKIES TONIGHT. SATELLITE IMAGERY SHOWS RAPIDLY COOLING
TOPS IN COLORADO AS 100KT H3 JET EMERGES FROM SOUTHERN ROCKIES
TROF. SFC LOW INTENSIFYING IN EASTERN COLORADO WILL TRACK UP THE
HIGH PLAINS TONIGHT. NEARLY STACKED LOWS WILL LIFT THROUGH WESTERN
SOUTH DAKOTA LATE TONIGHT INTO TUESDAY...A GOOD POSITION TO BRING
OUR FAR EAST A PERIOD OF MODERATE TO HEAVY RAINFALL. ALL MODELS
HAVE COME IN LINE HERE IN SHOWING STRONG QG FORCING AND MID LEVEL
FRONTOGENESIS IMPACTING OUR EAST. WILL MAKE LITTLE CHANGE TO
FORECAST...WITH CATEGORICAL POPS AND OVER AN INCH AND A HALF OF
PCPN FOR FALLON/CARTER COUNTIES BY TOMORROW EVENING. SHOULD ALSO
SEE A FEW EMBEDDED TSTMS NEAR THE DAKOTAS BORDER PER ELEVATED
INSTABILITY. THERE WILL BE A SHARP CUT OFF TO THE PCPN ON THE
WESTERN SIDE...WHEREAS MILES CITY SHOULD GET SOME RAIN TOMORROW
AMOUNTS WILL BE MUCH LESS. BILLINGS WILL BE UNAFFECTED. SYSTEM
WILL DEPART TO OUR NORTHEAST TUESDAY NIGHT. SHOULD ALSO POINT OUT
THE INCREASE IN W-NW WINDS TOMORROW AS SFC LOW TRACKS JUST TO OUR
WEST...A CHANGE FROM THE EAST WINDS WE HAVE SEEN OF LATE.

OTHERWISE...NEXT PACIFIC SHORTWAVE WILL BRING MORE SHOWERS TO OUR
WEST BY TUESDAY AFTERNOON WITH A CHANCE OF SHOWERS LINGERING INTO
WEDNESDAY AS ANOTHER WEAKER WAVE COMES THROUGH. LOW LEVELS WILL BE
STRONGLY DOWNSLOPED AND THIS WILL LIMIT PCPN AMOUNTS. 700MB TEMPS
FALL BELOW 0C TUESDAY NIGHT SO EXPECT SOME SNOW OVER THE HIGHER
PEAKS...A LOWER SNOW LEVEL THAN WE SAW WITH THE MOST RECENT
SYSTEM. FLAT RIDGING/SUBSIDENCE SHOULD BRING US A DRY AND
SEASONABLY COOL NIGHT WEDNESDAY NIGHT. GUSTY W-NW WINDS WILL
PERSIST THROUGH WEDNESDAY.

TEMPS WILL TAKE ANOTHER STEP UP TOMORROW WITH HIGHS WELL INTO THE
60S...OR JUST ABOUT NORMAL FOR THE END OF SEPTEMBER. COLD FRONT
WILL BRING COOLER TEMPS FOR WEDNESDAY...MAINLY UPPER 50S TO LOWER
60...WITH THE DOWNSLOPE WINDS KEEPING OUR TEMPS FROM FALLING TOO
FAR.

JKL

.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...

QUIET WEATHER EXPECTED THROUGH THE EXTENDED FORECAST PERIOD.
OVERALL EXPECT TO SEE A SLOW WARMING TREND AS DRY NORTHWESTERLY
FLOW PERSISTS OVER THE FORECAST AREA. ONLY WRINKLE WILL BE
THURSDAY / THURSDAY NIGHT AS A WEAK SHORTWAVE TROUGH PASSAGE WILL
PUSH IN A BACKDOOR COLD FRONT. THE 12Z EC CAME IN A BIT STRONGER /
FARTHER SOUTH WITH THIS SHORTWAVE...AND OUT OF RESPECT TO THIS
POSSIBILITY...COOLED FORECAST HIGH TEMPERATURES SLIGHTLY AND
INTRODUCED A SLT CHC POPS THURSDAY AFTERNOON / EVENING. FOR FRIDAY
AND BEYOND RISING HEIGHTS IN THE NORTHWEST FLOW WILL BUILD INTO
THE AREA AS RIDGING BECOMES STRONGER TO OUR WEST. THIS WILL RESULT
IN DRY CONDITIONS AND A WARMING TEMPERATURE TREND. HIGH
TEMPERATURES IN THE 70S ARE LIKELY BY THE WEEKEND.

LOOKING OUT EVEN FARTHER...THROUGH THE FIRST WEEK OF
OCTOBER...MODELS SEEM TO BE IN FAIR AGREEMENT ABOUT MAINTAINING
NORMAL TO ABOVE NORMAL TEMPERATURES WITH A BELOW NORMAL CHANCE OF
PRECIPITATION. LATEST CFS RUNS HAVE ALSO CAUGHT ONTO THIS WARMER
AND DRIER TREND THROUGH THE FIRST HALF OF OCTOBER...SO THERE IS
SOME CONFIDENCE IN HOLDING OFF ANY COLDER OR WETTER SPELL FOR A
WEEK OR TWO LONGER. THE ONLY CAVEAT TO THIS OUTLOOK IS WHETHER ANY
TYPHOONS DEVELOP IN THE EAST PACIFIC AND KICK THE LONG-WAVE
PATTERN OVER THE PACIFIC WHILE GOING EXTRA-TROPICAL. CHURCH

&&

.AVIATION...

IFR TO LIFR CONDITIONS ARE EXPECTED IN SOUTHEASTERN MT TONIGHT AS
LOW CLOUDS AND PATCHY FOG EXPAND. FOG MAY DEVELOP WESTWARD NEARLY
TO KBIL FOR A TIME BEFORE WESTERLY WINDS KICK IN THERE BY 09 UTC.
RAIN AND ISOLATED THUNDERSTORMS WILL ARRIVE IN SOUTHEASTERN MT BY
09 UTC AND THEN CONTINUE INTO TUESDAY ALONG WITH IFR OR EVEN LIFR
CONDITIONS IN THE KBHK...K4BQ...AND POSSIBLY KMLS AREAS. SCHULTZ

&&

.PRELIMINARY POINT TEMP/POPS...

    TUE     WED     THU     FRI     SAT     SUN     MON
-----------------------------------------------------------
BIL 049/067 044/060 042/057 036/068 049/074 050/071 047/069
    12/W    22/W    12/W    00/U    00/U    11/U    10/U
LVM 045/066 037/057 035/060 035/067 043/071 042/069 041/068
    23/W    32/W    12/W    00/U    00/U    11/U    10/U
HDN 045/069 043/061 039/059 035/069 046/074 047/073 044/070
    12/W    22/W    12/W    10/U    00/U    11/U    10/U
MLS 048/065 047/060 041/057 032/064 046/073 048/070 044/068
    37/W    32/W    11/B    00/U    00/U    11/U    10/B
4BQ 048/062 044/060 039/059 032/064 045/071 047/070 044/068
    88/T    22/W    12/W    20/U    00/U    11/U    10/U
BHK 048/059 045/059 038/056 029/057 040/068 045/065 041/063
    9+/T    52/W    11/N    10/U    00/U    11/U    10/B
SHR 047/065 042/057 034/060 032/067 042/071 045/070 040/068
    22/W    22/W    12/W    20/U    00/U    11/U    10/U

&&

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

&&

$$
WEATHER.GOV/BILLINGS


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