Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 242255
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
355 PM MST SAT JAN 24 2015

.SHORT TERM...VALID FOR SUN AND MON...

AFTERNOON INSTABILITY AND SHORTWAVE OVER EASTERN MONTANA HAS
TRIGGERED FAST MOVING SHOWER ACTIVITY WHICH IS PRODUCING BRIEF
STRONG WIND GUSTS. A COMBINATION OF PRESSURE GRADIENTS AND
MOMENTUM TRANSFER IS CONTRIBUTING TO BREEZY CONDITIONS ACROSS THE
REGION BUT EXPECT WINDS TO SETTLE A BIT IN THE EVENING AS
GRADIENTS SLACKEN AND WEAK INVERSIONS SLOW DOWN THE MOMENTUM
TRANSFER. WILL SEE A DRYING TREND THIS EVENING WITH THE LOSS OF
INSTABILITY AND DRIER AIR MOVING INTO THE REGION.

UPSTREAM RIDGE THAT HAS BEEN DRIVING THE NORTHWEST FLOW ALOFT THIS
AFTERNOON STARTS TO SHIFT EAST TONIGHT WHILE IT GETS FLATTEN BY
ANOTHER SURGE OF JET ENERGY MOVING ACROSS SOUTHERN BC AND ALBERTA.
THIS ALLOWS THE NEXT LEESIDE TROUGH TO BEGIN DEVELOPING OVERNIGHT
AND CAUSES GAP FLOW WINDS TO BEGIN INCREASING AGAIN. THESE WINDS
WILL BECOME STRONGER DURING THE MORNING HOURS PRESSURES WHILE THE
UPPER RIDGE KEEPS STRONG SURFACE HIGH PRESSURE OVER THE SNAKE
RIVER PLAIN. THE WINDS WILL SPREAD INTO THE PLAINS BUT GUSTS
SHOULD NOT BE QUITE AS HIGH AS SATURDAY WINDS WITH A BIT LESS
MOMENTUM ALOFT. THE MIXING SHOULD PROMOTE UNSEASONABLY WARM
TEMPERATURES INTO THE 50S EXCEPT IN SOUTHEAST MONTANA. SHOULD BE
DRIER WITHOUT SHOWER ACTIVITY EXCEPT OVER THE MOUNTAINS WHERE
OROGRAPHIC SHOWER ACTIVITY WILL DEVELOP.

SUNDAY NIGHT RIDGE AXIS CONTINUES ITS EASTWARD MOVEMENT AND EXPECT
DIURNAL COOLING OVER IDAHO AND WYOMING WILL SUPPORT AN INCREASE IN
WINDS FOR GAP FLOW AREAS ESPECIALLY AS THE MODELS SHOW AN AREA OF
SURFACE LOW PRESSURE DEVELOPING OVER SOUTHERN ALBERTA. MODELS NOT
HINTING AT AS DISTINCT A LEESIDE TROUGH BUT SUSPECT GRADIENTS WILL
SUFFICIENTLY TIGHTEN UP TO KEEP GAP FLOW WINDS AT ADVISORY LEVELS.
EXPECT A MILD NIGHT WITH TEMPERATURES NEARLY 20 DEGREES ABOVE
NORMAL.

MONDAY RIDGE AXIS MOVES INTO SOUTHWEST MONTANA AND FLATTENS WHICH
BRINGS WARMER AIR ALOFT INTO THE REGION AND KEEPS A DOWNSLOPE WIND
GOING. THIS COMBINATION WILL PUSH TEMPERATURES EVEN HIGHER AND
BILLINGS WILL BREAK A WEAK RECORD WHICH IS ONLY 54 DEGREES FOR THE
26TH AND A NUMBER OF AREAS COULD HIT THE 60S. TEMPERATURES STAY
MILD MONDAY NIGHT WITH CONTINUED DRY CONDITIONS WITH SOME AREAS
SEEING A DECREASE IN WINDS AS THE LEESIDE TROUGH SHIFTS INTO
SOUTH CENTRAL MONTANA. BORSUM

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

A STRONG RIDGE OF HIGH PRESSURE WILL CONTINUE TO HOLD FIRM ACROSS
THE NORTHERN ROCKIES ON TUESDAY RESULTING IN DRY CONDITIONS AND
ONE MORE DAY OF ABOVE NORMAL TEMPERATURES WHEN SOME LOWER
ELEVATIONS COULD HIT 60 DEGREES. MODELS CONTINUE TO SHOW A
DISTURBANCE MOVING ACROSS THE AREA TUESDAY INTO TUESDAY NIGHT
FLATTENING THE RIDGE WEDNESDAY INTO THURSDAY. THIS WILL BRING A
SLIGHT CHANCE FOR RAIN AND SNOW SHOWERS TUESDAY/TUESDAY NIGHT BUT
THE MAIN PORTION OF THE ENERGY WILL STAY TO OUR SOUTH ACROSS
WYOMING AND COLORADO. A SURFACE LOW WILL MOVE ACROSS NORTHERN
MONTANA TUESDAY NIGHT INTO WEDNESDAY MORNING BRINGING A COLD FRONT
ACROSS THE AREA WITH NORTHWEST WINDS BY WEDNESDAY AFTERNOON. NOT
MUCH PRECIP IS EXPECTED WITH THE FRONT SO MAINLY DRY CONDITIONS
WILL CONTINUE EXCEPT CHANCES FOR MOUNTAIN SNOW SHOWERS. MODELS
CONTINUE TO SHOW AN ARCTIC FRONT BACKING INTO THE FORECAST AREA
LATE FRIDAY INTO NEXT WEEKEND. HOWEVER...THE MAIN THRUST OF THE
ARCTIC AIR CONTINUES TO LOOK TO BE ACROSS NORTH DAKOTA...AND AT
THIS TIME...IT LOOKS TO BE A BRIEF SHOT BEFORE RIDGING TRIES TO
BUILD IN BY NEXT MONDAY. HOOLEY


&&

.AVIATION...

SKIES WILL BECOME CLEAR TO PARTLY CLOUDY TONIGHT WITH VFR
CONDITIONS PREVAILING. THE EXCEPTION WILL BE OVER THE MOUNTAINS
AND ADJACENT FOOTHILLS WHERE SOME MOUNTAIN OBSCURATIONS WILL BE
POSSIBLE DUE TO SNOW SHOWER ACTIVITY. VERY STRONG WINDS WILL
RETURN LATE THIS EVENING AND CONTINUE THROUGH THE DAY SUNDAY FROM
BIG TIMBER TO KLVM AND ALONG THE EASTERN FOOTHILLS OF THE
BEARTOOTH/ABSAROKA MOUNTAINS WITH SPEEDS OF 30-40KTS AND GUSTS
AROUND 55KTS. HOOLEY

&&

.PRELIMINARY POINT TEMP/POPS...

    SUN     MON     TUE     WED     THU     FRI     SAT
-----------------------------------------------------------
BIL 035/052 039/056 036/058 038/051 027/043 026/038 018/030
    11/N    00/N    00/U    12/W    11/B    12/O    32/S
LVM 035/055 038/059 035/058 036/051 026/047 024/041 018/035
    11/N    00/N    00/U    13/W    11/B    12/R    32/S
HDN 028/049 029/052 028/054 033/048 023/042 022/038 015/029
    01/E    00/B    00/U    12/W    11/B    12/O    32/S
MLS 028/046 033/050 030/052 033/044 025/041 024/036 014/024
    01/E    00/B    00/U    12/W    11/B    13/S    21/E
4BQ 028/049 034/054 030/055 032/048 024/042 023/038 015/027
    21/E    00/B    00/U    02/W    11/B    12/O    21/E
BHK 025/043 032/049 029/052 032/042 024/038 022/034 010/020
    10/E    00/B    00/U    02/W    11/B    13/S    21/E
SHR 028/050 031/057 028/056 029/047 020/040 018/037 013/027
    21/B    00/U    00/U    02/W    21/B    02/S    32/S

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WIND ADVISORY IN EFFECT UNTIL MIDNIGHT MST SUNDAY NIGHT FOR
      ZONES 41-65-66.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS



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