Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 282127
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
327 PM MDT FRI AUG 28 2015

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

HOT WEATHER IS EXPECTED SATURDAY ALONG WITH CRITICAL FIRE WEATHER
CONDITIONS OVER PORTIONS OF THE AREA...BEFORE A LOW-END CHANCE OF
SHOWERS AND STORMS AND SOMEWHAT COOLER TEMPERATURES ARRIVE SUNDAY.

TONIGHT...SMOKE FROM PACIFIC NORTHWEST WILDFIRES WILL CONTINUE TO
AFFECT THE AREA...AND WILL BE ESPECIALLY THICK IN SOUTHEASTERN MT
WHERE SURFACE VISIBILITIES ARE ALREADY UNDER 3SM IN SOME LOCATIONS
THIS AFTERNOON. FLOW ALOFT WILL BACK BY LATE TONIGHT THOUGH AS THE
500-MB RIDGE AXIS THAT/S OVERHEAD THIS AFTERNOON SHIFTS EAST...AND
THAT MAY HELP REDUCE THE SMOKE SOME AFTER MIDNIGHT. OTHERWISE...IT
WILL BE A QUIET NIGHT WITH LOWS MAINLY FROM 55 TO 65 F.

SATURDAY...HIGHS WILL REACH WELL INTO THE 90S F AND SHOULD HIT 100
F IN PLACES LIKE MILES CITY WITH SOUTHWEST FLOW ALOFT AND 700-MB
TEMPERATURES OF +14 TO +16 C. WE DID KEEP FORECAST HIGHS SLIGHTLY
UNDER MOST OF THE 12 UTC GUIDANCE GIVEN SOME UNCERTAINTY IN SMOKE
COVERAGE ALOFT...BUT IF IT DOES DECREASE SIGNIFICANTLY THEN HIGHS
COULD BE A FEW DEGREES F WARMER. DAILY RECORD HIGHS FOR AUGUST
28TH COULD BE IN JEOPARDY IN BILLINGS /THE CURRENT ONE IS 97 F/
AND MILES CITY /WHERE THE CURRENT RECORD IS 101 F/. WINDS WILL BE
GUSTY SATURDAY AFTERNOON AND EVENING IN SOUTH CENTRAL MT WITH SOME
GUSTS OF 25 TO 35 MPH...YIELDING CRITICAL FIRE WEATHER CONDITIONS.
WE HAVE UPGRADED THE FIRE WEATHER WATCH TO A RED FLAG WARNING. THE
ONLY UNCERTAINTY WE HAD WAS WITH THE EASTERN PIECE OF THE HEADLINE
IN MUSSELSHELL AND YELLOWSTONE COUNTIES...WHERE WINDS COULD END UP
BEING SOMEWHAT MARGINAL FOR A WARNING. HOWEVER...MODEL SOUNDINGS
IN THOSE AREAS HAD MEAN WINDS OF 20 KT IN THE WELL-MIXED BOUNDARY
LAYER DURING THE AFTERNOON WHICH WAS ENOUGH TO TIP THE SCALES TO
A WARNING IN THOSE COUNTIES AS WELL. FURTHER EAST IN SOUTHEASTERN
MT...WIND SPEEDS WILL BE LOWER IN CLOSER PROXIMITY TO A SURFACE
PRESSURE TROUGH...SO WE HELD OFF ON ANY FIRE WEATHER HEADLINES
THERE EVEN THOUGH HUMIDITIES WILL BE LOW. HOWEVER...THE 12 UTC NAM
HAD A BIT STRONGER WIND FIELDS AROUND BAKER THAN THE 12 UTC
GFS...AND IF IT ENDS UP BEING CORRECT...WE COULD STILL NEED A RED
FLAG WARNING IN FAR SOUTHEASTERN MT WITH A LATER FORECAST.

SATURDAY NIGHT...A WEAK COLD FRONT WILL CROSS THE AREA...BUT THE
12 UTC MODEL GUIDANCE SUGGESTS IT WON/T HAVE MUCH IMPACT BECAUSE
IT WILL LARGELY WASH OUT AS IT MOVES EASTWARD. WE NONETHELESS ARE
CARRYING LOW-END POPS FOR SHOWERS AND WEAK THUNDERSTORMS ACROSS
PARTS OF SOUTH CENTRAL MT AND NORTH CENTRAL WY...MAINLY AFTER 06
UTC.

SUNDAY...TEMPERATURES WILL BE COOLER /FROM THE MID 80S TO LOWER
90S F/ WITH LOWER HEIGHTS ALOFT. SOUTHWEST 500-MB FLOW AND MODEL
QPF OUTPUT SUPPORTS A LOW CHANCE OF SHOWERS AND THUNDERSTORMS AS
WELL. WE DO NEED TO NOTE THAT THE 12 UTC GFS SIMULATES A RATHER
STRONG SHORTWAVE TROUGH AND PACIFIC COLD FRONTAL PASSAGE SUNDAY
EVENING...WHICH IS A NEW TREND. IF THAT ENDS UP BEING RIGHT...WE
MAY HAVE SOME ENHANCED PRE-FRONTAL WARMING AND A WIND SHIFT THAT
COULD BRING MORE FIRE WEATHER CONCERNS BY SUNDAY EVENING. SCHULTZ

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

NOT A LOT HAS CHANGED IN THE EXTENDED FORECAST AND MODELS
CONTINUE IN PRETTY GOOD AGREEMENT THROUGH THE PERIOD. A MEAN UPPER
TROUGH REMAINS IN POSITION THROUGH WEDNESDAY. THIS WILL KEEP THE
FORECAST AREA IN DOWNSLOPE FLOW...PROVIDING ABOVE NORMAL
TEMPERATURES. THE UPPER TROUGH DOES MAKE A VERY SLOW EASTWARD
PROGRESSION AND THIS WILL LOWER HEIGHTS BY THE END OF THE
WEEK...EVENTUALLY BRINGING IN COOLER TEMPERATURES. THE CHANCE OF
PRECIPITATION WILL BE CONFINED THE HIGHER TERRAIN AS MONSOON FLOW
LOOKS TO BE DIRECTED INTO THE CENTRAL PLAINS WITH THE SOUTHERN
ROCKIES ACTUALLY GETTING INTO A DRIER 500MB FLOW OFF OF SOUTHERN
CALIFORNIA. THE BEST CHANCE OF SHOWERS LOOKS TO BE LATE IN THE
WEEK AS THE UPPER TROUGH AXIS ADVANCES INTO WESTERN IDAHO...BUT
EVEN THEN...MID LEVEL FLOW DOES LOOK DRY AND DYNAMICS WERE
DIRECTED NORTH. LOOKS LIKE A DRY AND WARM EXTENDED FORECAST. TWH

&&

.AVIATION...

A THICK LAYER OF SMOKE WILL BE OVER THE AREA THIS AFTERNOON AND
EVENING...AND THIS MAY CAUSE OCCASIONAL MVFR CONDITIONS. THE FLOW
ALOFT WILL CHANGE TO MORE SOUTHWEST AND SHOULD ALLOW SMOKEY
CONDITIONS TO IMPROVE LATE THIS EVENING. MOUNTAINS WILL BE
OBSCURED. OTHERWISE...VFR FLYING WEATHER IS EXPECTED. TWH

&&

.PRELIMINARY POINT TEMP/POPS...

    SAT     SUN     MON     TUE     WED     THU     FRI
-----------------------------------------------------------
BIL 063/096 067/086 054/082 055/086 059/085 054/077 048/075
    00/B    22/T    21/U    11/B    11/B    11/B    22/T
LVM 057/090 058/082 045/079 047/082 050/082 046/075 042/076
    11/N    22/T    21/B    11/B    11/B    12/T    22/T
HDN 060/099 064/089 053/085 055/089 057/088 053/080 048/079
    00/B    22/T    21/U    11/B    11/B    11/B    22/T
MLS 063/100 066/091 057/085 057/090 060/090 057/082 051/081
    00/U    02/T    21/U    11/U    11/U    11/U    22/T
4BQ 060/099 062/093 057/085 057/089 060/091 056/083 053/079
    00/U    02/T    21/U    11/U    11/U    11/U    22/T
BHK 059/097 062/094 056/085 056/088 058/091 056/083 053/079
    00/U    02/T    21/U    11/U    11/U    11/U    22/T
SHR 055/095 059/090 050/084 050/087 052/088 051/081 046/077
    00/U    12/T    21/U    11/B    11/B    11/B    22/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...RED FLAG WARNING IN EFFECT FROM NOON TO 9 PM MDT SATURDAY FOR
      ZONES 28-29-34-35-39>42-56-63>68.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS


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