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000
FXUS65 KBYZ 081602
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
902 AM MST SAT MAR 8 2014

.UPDATE...
A VARIETY OF FLOOD WARNINGS AND ADVISORIES REMAIN IN EFFECT...
DUE TO RECENT LOW ELEVATION SNOW MELT AND ICE JAMS. COOLER TEMPS
THE LAST COUPLE DAYS HAVE SLOWED THE SNOW MELT...AND THERE IS MUCH
LESS SNOW WATER AVAILABLE...SO SOME WATER LEVELS HAVE DECREASED.
ICE JAM CONCERNS WILL EXIST INTO NEXT WEEK HOWEVER.

TODAYS WEATHER WILL OTHERWISE BE QUIET AND WARM AS UPPER RIDGE
BUILDS OVER THE AREA. TEMPS WILL TOP OUT INTO THE LOW/MID 50S MANY
PLACES. WINDS WILL INCREASE IN OUR WEST DUE TO TIGHTENING
DOWNSLOPE GRADIENTS...AND GUSTS ALREADY IN THE 40S AT LIVINGSTON.
ADVISORY SPEEDS AT THE GAP AREAS ARE A CERTAINTY BY TONIGHT AND
BELIEVE GUSTS WILL REACH 70 MPH AT TIME OF PEAK STABILITY LATE
TONIGHT AND SUNDAY MORNING. HAVE MADE A FEW WIND ADJUSTMENTS HERE.

JKL

&&

.SHORT TERM...VALID FOR TDY AND SUN...

LITTLE CHANGES MADE TO THE SHORT TERM FORECAST WITH THIS ISSUANCE
AS A DRY AND MILD WEEKEND IS EXPECTED. HIGH PRESSURE RIDGING WILL
BUILD ACROSS THE FORECAST AREA TODAY INTO SUNDAY BRINGING PARTLY
TO MOSTLY SUNNY SKIES ALONG WITH WELL ABOVE NORMAL TEMPERATURES AS
READINGS WILL BE IN THE UPPER 40S TO LOWER 50S TODAY. WINDS WILL
BECOME GUSTY THIS AFTERNOON AS LEE-SIDE TROUGHING BEGINS TO
DEVELOP. A SURFACE LOW WILL DEVELOP AND MOVE ACROSS SOUTHERN
CANADA WHILE SURFACE HIGH PRESSURE WILL BE SITUATED OVER EASTERN
IDAHO. THIS WILL ALLOW PRESSURE FALLS TO OCCUR ACROSS THE EASTERN
SLOPES OF THE ROCKY MOUNTAIN FRONT RANGE. THIS WILL RESULT IN
TIGHT PRESSURE GRADIENTS ACROSS THE UPPER YELLOWSTONE VALLEY WITH
THE GRADIENT ORIENTATION FAVORABLE FOR ADVISORY WINDS FOR THE
LIVINGSTON AND NYE AREAS. AS A RESULT...HAVE ISSUED A WIND
ADVISORY FOR THOSE AREAS FOR THIS AFTERNOON THROUGH SUNDAY NIGHT
WITH THE STRONGEST WINDS ARE EXPECTED TONIGHT THROUGH THE DAY
SUNDAY. WILL HOLD OFF ON AN ADVISORY FOR THE BIG TIMBER AREA BUT
WILL NEED TO MONITOR TRENDS THERE AS THE GRADIENT ORIENTATION IS
BORDERLINE AT THIS TIME.

SUNDAY WILL SEE THE RIDGE BEGIN TO BREAK DOWN AS A TROUGH AND
UPPER LEVEL DISTURBANCE MOVE ONTO THE PACIFIC NORTHWEST COAST.
THIS WILL SWEEP A COLD FRONT ACROSS THE FORECAST LATE SUNDAY NIGHT
OR MONDAY MORNING. EXPECT SOME GOOD COMPRESSIONAL WARMING AHEAD OF
THIS FRONT WITH AFTERNOON TEMPERATURES CLIMBING WELL INTO THE 50S
AND LOWER 60S. MODELS HAVE SLOWED DOWN THE ONSET OF SHOWER
ACTIVITY SO HAVE REMOVED PRECIP CHANCES FROM THE CENTRAL AREAS
SUNDAY AFTERNOON AND EVENING BUT KEPT PRECIP CHANCES ACROSS THE
FAR WESTERN VALLEYS AND MOUNTAINS.

FLOODING CONCERNS WILL CONTINUE INTO EARLY NEXT WEEK MAINLY FROM
ICE JAMS ACROSS THE AREA. SNOW COVER ACROSS THE LOWER ELEVATIONS
HAS BEEN DECREASING QUITE A BIT SO THIS WILL HELP SOME OF THE
FLOODING THAT HAS BEEN OCCURRING. IN ADDITION...THE WARM
TEMPERATURES THIS WEEKEND WILL HELP TO SOMEWHAT THAW THE FROZEN
GROUND WHICH SHOULD ALLOW SOME OF THE REMAINING SNOWMELT TO SOAK
INTO THE GROUND. WILL CONTINUE WITH ALL CURRENT HYDRO PRODUCTS AND
EVALUATE THROUGHOUT THE DAY. HOOLEY

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

MAIN CONCERN FOR THE EXTENDED PERIOD WILL BE THE PACIFIC SYSTEM
THAT WILL AFFECT THE AREA MON THROUGH TUE. ENSEMBLE SITUATIONAL
AWARENESS TABLE SHOWED ANOMALOUSLY HIGH MEAN INTEGRATED WATER
VAPOR TRANSPORT OVER THE AREA ON MON THAT MOVES S THROUGH THE DAY.
THE MEAN SREF QPF FOR KLVM WAS /.55/ INCHES THROUGH MON NIGHT.
THE GFS AND ECMWF BOTH SHOWED DECENT AMOUNTS OF QPF THROUGH MON
NIGHT BUT DISAGREED ON THE PLACEMENT OF THE HIGHEST AMOUNTS.
SHOULD A DECENT AMOUNT OF MOISTURE FALL ONTO THE HIGH ELEVATION
SNOWPACK...THERE WILL LIKELY BE ADDITIONAL FLOODING
PROBLEMS...THUS THIS SYSTEM WILL NEED TO BE CLOSELY WATCHED.

MODELS DID AGREE ON MOVING A SHORTWAVE ACROSS THE AREA THROUGH TUE
AND THE GFS HAD STRONG FRONTOGENESIS WITH THE SYSTEM...ESPECIALLY
OVER THE SW. THE FRONTOGENESIS MOVES S OF THE AREA DURING MON
NIGHT. THE AIRMASS WILL NOT GET VERY COLD WITH THIS SYSTEM AND
WILL PRODUCE MAINLY RAIN ON MON. THE RAIN WILL CHANGE TO SNOW MON
NIGHT AS 850 MB TEMPERATURES FALL A LITTLE BELOW ZERO DEGREES C.
EXPECT MAINLY SNOW FOR THE MOUNTAINS WITH A MIX POSSIBLE FOR THE
NE BIG HORNS. HAVE INCREASED POPS FOR THE SYSTEM THROUGH MON NIGHT AND
WENT WITH A BLEND OF THE GFS AND ECMWF FOR THE QPF. THE SYSTEM
WILL WIND DOWN ON TUE AS THE WAVE MOVES S OF THE AREA. HIGHS WILL
BE IN THE 40S AND 50S AHEAD OF THE FRONT ON MON AND IN THE 40S ON
TUE.

UPPER RIDGING WILL BRING WARM AND DRY WEATHER TO THE AREA FOR WED.
A SHORTWAVE WILL CROSS THE AREA IN NW FLOW ON THU BUT THE MODELS
WERE DRY. WINDS MAY PICK UP FOR THE GAP FLOW AREAS LATE WED
THROUGH EARLY THU. MOISTURE WILL INCREASE OVER THE AREA FRI
THROUGH SAT AS NW FLOW CONTINUES WITH WAVES MOVING THROUGH THE
FLOW. HAD MOUNTAIN POPS FOR FRI...THEN CLIMATOLOGICAL POPS FOR
SAT. HIGH TEMPERATURES WILL BE IN THE 50S FOR WED THROUGH THE END
OF THE PERIOD. ARTHUR
&&

.AVIATION...

VFR CONDITIONS WILL PREVAIL OVER THE AREA TODAY AND TONIGHT. SW
SURFACE WINDS WILL INCREASE OVER KLVM TO 30 TO 40 KT WITH GUSTS TO
50 KT THIS AFTERNOON AND CONTINUE THROUGH TONIGHT. CHURCH

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY SUN     MON     TUE     WED     THU     FRI
-------------------------------------------------------
BIL 052 035/059 038/044 027/042 028/050 033/052 032/050
    0/N 00/N    28/R    72/O    10/U    00/U    11/B
LVM 053 038/057 038/044 024/040 023/047 029/049 029/048
    0/N 02/W    39/R    75/O    10/N    00/N    11/B
HDN 050 028/056 035/047 026/044 026/054 032/056 035/051
    0/U 00/N    28/O    62/O    10/U    00/U    11/B
MLS 050 030/058 036/050 027/045 028/053 035/052 032/050
    0/U 00/B    14/R    42/O    10/U    00/U    11/B
4BQ 049 029/062 035/055 028/043 025/052 032/056 035/051
    0/U 00/B    14/R    72/O    10/U    00/U    11/B
BHK 048 029/058 033/050 025/043 027/051 033/049 031/047
    0/U 00/N    03/O    32/O    10/U    00/U    11/B
SHR 055 027/061 035/059 026/041 022/050 027/053 028/049
    0/U 00/U    16/R    84/O    10/U    00/U    11/B

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WIND ADVISORY IN EFFECT FROM 3 PM MST THIS AFTERNOON TO 6 AM
      MDT MONDAY FOR ZONES 65-66.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS