Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 260404
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
904 PM MST SUN JAN 25 2015

.UPDATE...
FORECAST CHALLENGE THIS EVENING IS IN WHAT TO DO WITH THE
EXISTING ADVISORY FOR THE BEARTOOTH/ABSAROKA FOOTHILLS. WINDS HAVE
BEEN BELOW ADVISORY CRITERIA ALL EVENING...BUT HAVE EDGED UP THE
LAST COUPLE OF HOURS. SURFACE PRESSURE DIFFERENCE BETWEEN IDAHO
FALL AND LEWISTOWN WAS DECREASING A BIT. SURFACE PRESSURE
TENDENCIES WERE FOR RISES OVER MONTANA WITH A SMALL SURGE IN FALLS
OVER BRITISH COLUMBIA. 00Z GFS PROJECTED SURFACE PRESSURE FALLS
INTO NORTHERN IDAHO OVERNIGHT AND THESE FALLS WERE NOT PROJECTED
TO BET THAT DRAMATIC. 700MB WINDS ALSO DECREASE FROM 50KTS TO
40KTS AND BACK SLIGHTLY THROUGH THE NIGHT. THERE IS A DECENT
STABLE LAYER NEAR MOUNTAIN TOP LEVEL THAT SHOULD DRIVE SOME GAP
FLOW...BUT DO NOT SEE TREMENDOUSLY COLD TEMPERATURES IN THE PARK.
THESE THINGS POINT TO WINDS NOT RAMPING BACK UP INTO ADVISORY
CRITERIA THE REST OF THE NIGHT. STILL WILL BE WINDY THE REST OF
THE NIGHT...JUST NOT EXPECTING WINDS TO KICK BACK UP INTO ADVISORY
CRITERIA. WILL THEREFORE DROP THE ADVISORY. THE REST OF THE
FORECAST LOOKS IN GOOD SHAPE. TWH

&&

.SHORT TERM...VALID FOR MON AND TUE...

DRY AND WARM WEATHER EXPECTED THE NEXT FEW DAYS WITH SOME AREAS
CLIMBING INTO THE 60S. RECORD LIKELY TO BE BROKEN MONDAY AT
BILLINGS WHERE OLD RECORD IS 54. UPPER LEVEL RIDGE MOVING TOWARDS
THE AREA FROM THE GREAT BASIN IS BRINGING WARM AIR ALOFT WITH IT
WHICH IS HELPING BOOST THE TEMPERATURES. ENOUGH FLOW THROUGH THE
TOP OF THE RIDGE ACROSS CENTRAL MONTANA TO GENERATE LEESIDE TROUGH
BUT WEAKER THAN PREVIOUS DAYS. GAP FLOW AREAS WILL CONTINUE TO
HAVE A PERIOD OF STRONG WINDS THIS EVENING AS DIURNAL COOLING OVER
THE SNAKE RIVER PLAINS TIGHTENS PRESSURE GRADIENTS BUT EXPECT WINDS
TO BE DECREASING FOR THESE AREAS MONDAY. TUESDAY WILL BE EQUALLY
AS WARM AS MONDAY FOR MOST AREAS.

TWO PARTICULAR ASPECTS OF THE FORECAST TO MENTION. WHILE WINDS ARE
CURRENTLY BELOW ADVISORY CRITERIA AM NOT DROPPING THE HIGHLIGHT AT
THIS TIME FOR A COUPLE OF REASONS. A BIT BETTER MOMENTUM ALOFT IS
HEADING INTO THE REGION LATE THIS AFTERNOON AND THIS WILL HELP
ACCELERATE WINDS A BIT. ALSO THINK THAT AS THE SUN BEGINS TO SET
ANY WEAK UPVALLEY COMPONENT TO THE WINDS IN LIVINGSTON THAT IS
OFFSETTING CURRENT SPEEDS WILL GO AWAY AND DOWNVALLEY FLOWS WILL
PICK UP. ALSO EXPECT PRESSURE GRADIENTS TO INCREASE IN A BRIEF
WINDOW AS SNAKE RIVER PLAIN SHOULD COOL OFF QUICKER THAN THE
YELLOWSTONE VALLEY. SECOND ITEM IS HAVE RAISED BILLINGS
TEMPERATURE TO 60 FOR MONDAY. NORMALLY UNDER THIS PATTERN THIS
TIME OF YEAR FLOWS OUT OF THE BIG HORN BASIN WOULD HAVE A STRONG
COOLING EFFECT ON MAXIMUM TEMPERATURES WHILE PLACES ABOVE THE
VALLEY BOTTOMS WARM BETTER. WHILE GREYBULL IS ONLY 33F TODAY CODY
IS 59F SO SUSPECT THE COLD AIR DRAINAGE DOWN THE CLARKS FORK IS
ERODING FASTER THAN NORMAL BECAUSE BILLINGS HAS OVERACHIEVED ON
FORECAST TEMP THE PAST TWO DAYS. BORSUM

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

A DISTURBANCE THAT WILL MOVE ACROSS THE FORECAST AREA TUESDAY
NIGHT INTO WEDNESDAY MORNING WILL FLATTEN THE STRONG UPPER RIDGE
WEDNESDAY INTO THURSDAY. THIS WILL BRING A SLIGHT CHANCE FOR RAIN
AND SNOW SHOWERS WEDNESDAY MAINLY OVER AND ADJACENT TO THE
MOUNTAIN LOCATIONS. HOWEVER...THE MAIN ENERGY WILL STAY TO OUR
SOUTH ACROSS WYOMING AND COLORADO. MODELS THEN BEGIN TO BUILD THE
RIDGE AGAIN OVER THE PACIFIC NORTHWEST GIVING OUR AREA A DRY
NORTHWEST FLOW ALOFT. THE PAST SEVERAL MODEL RUNS ARE NOW CHANGING
THE OUTLOOK FOR NEXT WEEKEND IN PLACING A RIDGE WITH DOWNSLOPE
FLOW ACROSS THE AREA SATURDAY RESULTING IN MILD TEMPERATURES. A
STRONG PACIFIC FRONT MOVES ACROSS THE FORECAST AREA SUNDAY
BRINGING A SLIGHT SHOWER CHANCE BUT STRONG WEST TO NORTHWEST WINDS
WILL BRING A STRONG DOWNSLOPE FLOW TO THE AREA. TEMPERATURES WILL
CONTINUE TO BE ABOVE NORMAL WITH READINGS IN THE 40S AND 50S
WEDNESDAY...WITH 40S THROUGH THE REMAINDER OF THE PERIOD. HOOLEY

&&

.AVIATION...

SOME MID AND HIGH LEVEL CLOUDS WILL MOVE ACROSS THE FORECAST AREA
TONIGHT WITH VFR CONDITIONS PREVAILING. STRONG WINDS WILL CONTINUE
FOR THE BIG TIMBER...KLVM...AND BEARTOOTH/ABSAROKA FOOTHILLS
AREAS. HOOLEY/TWH

&&

.PRELIMINARY POINT TEMP/POPS...

    MON     TUE     WED     THU     FRI     SAT     SUN
-----------------------------------------------------------
BIL 041/062 039/058 039/052 030/046 026/043 026/042 029/046
    00/N    00/U    02/W    11/U    01/B    11/B    11/B
LVM 040/063 039/058 037/050 028/047 025/046 023/044 027/048
    00/N    00/U    12/W    10/B    11/B    11/B    11/N
HDN 032/052 030/052 032/049 024/045 021/042 020/039 021/043
    00/B    00/U    02/W    11/U    01/B    11/B    11/B
MLS 034/051 031/051 034/045 025/043 025/040 020/036 022/041
    00/B    00/U    01/B    11/U    01/B    11/B    11/B
4BQ 035/056 032/056 033/049 025/045 024/042 021/040 022/044
    00/B    00/U    01/B    10/U    01/B    11/B    11/B
BHK 034/051 031/053 033/043 025/040 024/039 017/032 019/038
    00/B    00/U    01/B    11/B    01/B    11/B    11/B
SHR 033/057 031/056 029/047 022/043 018/041 018/040 020/046
    00/U    00/U    02/W    10/U    11/B    11/B    00/B

&&

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

&&

$$
WEATHER.GOV/BILLINGS


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