Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 050241
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
741 PM MST WED MAR 4 2015

.UPDATE...
DRY NW FLOW OVER THE REGION TONIGHT. ANTICYCLONIC FLOW ALOFT HAS
RESULTED IN KLONDIKE CHINOOKING...AND WIND GUSTS HAVE EXCEEDED 30
MPH AT BIG TIMBER AND HARLOWTON SINCE LATE AFTERNOON. HAVE RAISED
WINDS AT THESE LOCATIONS...AND GUSTS SHOULD BE HIGHEST OVERNIGHT
AS PRESSURE GRADIENT CONTINUES TO TIGHTEN AS SHORTWAVE DROPS OUT
OF SASKATCHEWAN. THIS ENERGY WILL PRODUCE ONLY SOME HIGH CLOUD
OVER OUR CWA...SO ONLY REAL FORECAST ISSUES TONIGHT ARE TEMPS AND
WINDS. AS FOR TEMPS...ALREADY PUSHING ZERO AT SHERIDAN AND BAKER
SO HAVE DROPPED TEMPS A FEW DEGREES AT THESE LOCATIONS AS WELL AS
SOME OTHER SE MT VALLEYS. WARM ADVECTION AND INCREASED WINDS WILL
KEEP TEMPS MILDER ALONG OUR FOOTHILLS. STILL NEAR 30 DEGREES AT
BIG TIMBER AND HARLOWTON SO HAVE TWEAKED TEMPS UP SOME OUT WEST.

AT THIS TIME AGREE WITH THE DAY SHIFT THAT WIND HIGHLIGHTS ARE NOT
NEEDED GIVEN SUCH NORTHERLY FLOW ALOFT...WHICH IS NOT FAVORED FOR
PURE GAP FLOW. HAVE RAISED WINDS AT 3HT THROUGH TOMORROW THOUGH
WITH GUSTS OF 40+ MPH ANTICIPATED.

JKL

&&

.SHORT TERM...VALID FOR THU AND FRI...

OVERALL WEATHER PATTERN ON THE QUIET SIDE AS WE SLOWLY WARM UP
AND TRANSITION TO ANTI-CYCLONIC FLOW ALOFT. WE WILL HAVE SOME
CLOUDS FROM TIME TO TIME...ESPECIALLY OVER THE EASTERN BORDER
COUNTIES AND NEAR THE MOUNTAINS WITH SOME WEAK SHALLOW ENERGY
ALOFT PASSING BY...BUT NOTHING NEAR POTENT ENOUGH TO PRODUCE
PRECIPITATION AS LOWER LEVELS DRY OUT.

THE MAIN FORECAST ISSUE IS WIND AT THE USUAL GAP LOCATIONS
/LIVINGSTON AND NYE/ AS SURFACE TROUGHING DEVELOPS WITH THE
BUILDING HEIGHTS ALOFT. I HAVE BUMPED UP WINDS TO JUST UNDER
ADVISORY LEVEL IN THESE LOCATIONS STARTING NEAR 12Z THURSDAY
THROUGH THE DAY WHICH LOCAL GUIDANCE HINTS AT BEING THE MAIN
TIME FRAME FOR HIGHER WIND SPEEDS. WE WILL NEED TO WATCH TRENDS
AS WE COULD POSSIBLY NEED A WIND ADVISORY IN THESE LOCATIONS
LATE TONIGHT THROUGH FRIDAY...BUT PROGGS HAVE ME ON THE FENCE AND
WOULD RATHER FUTURE SHIFTS SEE SOME ADDITIONAL MODEL RUNS RATHER
THAN HANDCUFF THEM WITH WEAK HIGHLIGHTS. BT

.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...

NO MAJOR CHANGES TO THE GOING FORECAST. MODELS IN GOOD AGREEMENT
FOR WEEKEND WITH A WEAK TROUGH BREAKING DOWN THE RIDGE ALOFT AND
ALLOWING SOME COLDER AIR TO BACK DOOR INTO THE EASTERN ZONES
BY SATURDAY. GFS PAINTS SOME LOW VALUES OF QPF ACROSS THE CENTRAL
ZONES SATURDAY AFTERNOON WHICH DROPS SOUTH ONTO THE NORTH FACING
HIGHER TERRAIN BY EVENING. ECMWF KEEPS US DRY BUT DOES HAVE A
SIMILAR WEAK QC FORCING. HAVE OPTED TO HAVE SOME LOW POPS OVER
JUST THE HIGHER TERRAIN FOR NOW...ANYTHING AT LOWER ELEVATIONS
PROBABLY WOULD NOT MEASURE. CONFIDENCE IS GOOD THAT A SOMEWHAT
DIRTY RIDGE WILL PREVAIL THROUGH AT LEAST MONDAY. AT THAT POINT
THE EXTENDED MODELS DIVERGE. THE GFS GETS VERY UNSETTLED WITH
STRONG TROUGH DROPPING INTO THE NORTHERN ROCKIES ON TUESDAY...BUT
THE ECMWF KEEPS DIRTY RIDGE IN PLACE OVER OUR REGION. NO MODEL
CONSISTENCY AFTER MIDWEEK EITHER. THIS STRONG DIVERGENCE IN THE
MODEL SOLUTIONS MAKES ME THINK /BASED ON EXPERIENCE/ MODELS MAY
EVENTUALLY RESOLVE THINGS INTO AN ACTIVE ZONAL FLOW. AT ANY
RATE...WARMER TEMPERATURES MAY GIVE WAY TO UNSETTLED WEATHER...BUT
CONFIDENCE IS QUITE LOW IN HOW THINGS PAN OUT AFTER DAY 6. BT

&&

.AVIATION...

VFR CONDITIONS WILL PREVAIL INTO THURSDAY WITH AN INCREASE IN HIGH
LEVEL CLOUDINESS. WINDS WILL INCREASE IN THE FOOTHILLS OF SOUTH
CENTRAL MT...WITH GUSTS TO 45 KT LIKELY AT KLVM LATE TONIGHT AND
THURSDAY. FRIEDERS

&&

.PRELIMINARY POINT TEMP/POPS...

    THU     FRI     SAT     SUN     MON     TUE     WED
-----------------------------------------------------------
BIL 019/046 029/053 029/053 030/056 035/062 036/060 031/047
    00/N    00/N    01/B    10/U    00/U    00/U    22/W
LVM 021/047 029/052 032/053 031/055 035/059 037/058 036/049
    00/N    00/N    11/B    10/U    00/N    00/N    22/W
HDN 010/047 025/054 027/054 028/057 031/063 032/063 029/050
    00/B    00/E    01/B    10/U    00/U    00/U    02/W
MLS 008/046 027/053 027/051 028/055 032/060 033/058 029/046
    00/B    00/E    11/B    10/U    00/U    00/U    00/B
4BQ 003/043 021/048 023/049 026/053 029/060 030/060 028/048
    00/B    00/B    01/B    10/B    00/U    00/U    00/B
BHK 901/043 022/050 025/048 025/052 030/057 029/056 027/045
    00/B    00/E    21/B    10/U    00/U    00/N    00/B
SHR 901/043 022/049 024/049 025/052 028/060 030/059 028/048
    00/B    00/B    01/B    10/U    00/U    00/U    01/B

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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