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000
FXUS65 KBYZ 090349
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
849 PM MST SAT MAR 8 2014

.UPDATE...

MINOR UPDATE TO THE GOING FORECAST THIS EVENING. STRONGER WINDS
ALOFT BEGINNING TO PINCH SOUTH INTO THE AREA ARE DRIVING PRESSURE
FALLS EAST OF THE DIVIDE. THIS IS ALREADY GENERATING VERY STRONG
WIND IN THE GAP FAVORED AREAS FROM LIVINGSTON TO NYE. WINDS
GUSTING TO 68 MPH IN LIVINGSTON AND 55 MPH IN NYE ALREADY WITH
GRADIENT EXPECTED TO TIGHTEN FURTHER OVER THE NEXT 6 HOURS. CAN`T
RULE OUT A FEW GUSTS AT LIVINGSTON IN THE 75 MPH RANGE THROUGH THE
NIGHT TONIGHT...BUT GUIDANCE SUGGESTING THAT STRONGEST WINDS WILL
PEAK CLOSE TO CURRENT VALUES SO HELD OFF ON A HIGH WIND WARNING IN
LIVINGSTON FOR NOW. OTHER THAN TWEAKING CLOUD COVER THE FORECAST
LOOKS TO BE IN GOOD SHAPE.

FLOODING...RECEIVED SEVERAL REPORTS OF ICE JAM RELATED FLOODING
THIS EVENING PROMPTING ADDITIONAL FLOOD ADVISORIES TO BE ISSUED
FOR THE TONGUE...POWDER RIVER AND YELLOWSTONE RIVERS IN SOUTHEAST
MONTANA. A SERIES OF LARGER ICE JAMS ON THE YELLOWSTONE DID DAMAGE
IN TREASURE COUNTY TO EQUIPMENT AND BUILDINGS THIS AFTERNOON.
LATEST INFORMATION HAS THIS ICE NOW INTO ROSEBUD COUNTY FROM
FORSYTH TO ROSEBUD. EXPECT THIS ICE TO MOVE INTO CUSTER COUNTY
OVERNIGHT. AN ICE JAM ON THE BRANDENBERG BRIDGE IN ROSEBUD COUNTY
HAS BACKED UP WATER OVER THE TONGUE RIVER ROAD THERE. MORE ICE ON
THE POWDER RIVER EXTENDS FROM SOUTH OF BROADUS INTO CUSTER COUNTY
CAUSING LOW LAND FLOODING THERE. THE MOST SERIOUS THREAT FROM THIS
ICE IS LIKELY TO BE IN MILES CITY WHERE THE TONGUE IS ICE COVERED
AND ICE IS CONVERGING FROM THE WEST ON THE YELLOWSTONE AND SOUTH
ON THE TONGUE. EXPECT TO SEE FLOODING IN THE MILES CITY AREA
TOMORROW FROM THIS ICE CONVERGENCE AND FLOOD WARNING REMAINS IN
EFFECT THERE. LOW LAND FLOODING WILL BE POSSIBLE THROUGH TOMORROW
AS WELL ON THE OTHER WATERWAYS MENTIONED. WATER RISES WILL BE
RAPID AT TIMES...AS MUCH AS A FOOT A MINUTE TYPE RISES WERE
REPORTED IN TREASURE COUNTY ON THE YELLOWSTONE THIS AFTERNOON.
FLOODING AT NIGHT CAN BE EXTRA DANGEROUS SO THOSE LIVING ALONG
RIVERS AND STREAMS IN SOUTHEAST MONTANA SHOULD STAY ALERT TONIGHT.
WATER IS REPORTEDLY DOWN SIGNIFICANTLY ON PRYOR CREEK IN
YELLOWSTONE COUNTY BUT WILL WAIT UNTIL TOMORROW TO ENSURE FLOODING
POTENTIAL HAS PASSED BEFORE DROPPING THAT ADVISORY. CHAMBERS

&&

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

VARIETY OF FLOODING CONTINUES ACROSS THE AREA THIS AFTERNOON...
AND SEVERAL FLOOD WARNINGS AND ADVISORIES ARE IN EFFECT. RAPID LOW
ELEVATION SNOW MELT AND ICE JAMS ARE THE DRIVING FORCES BEHIND THE
FLOODING. PLEASE BE SAFE IF YOU LIVE IN A LOW LYING AREA OR NEAR A
RIVER PRONE TO EXPERIENCE ICE JAMS OVER THE NEXT FEW DAYS.

GAP WIND EVENT COMING TONIGHT FOR LIVINGSTON AND NYE...AND WE ARE
ALREADY SEEING GUSTS NEAR 50 MPH AT LIVINGSTON. ONCE WE MOVE PAST
PEAK HEATING AND STABILITY BEGINS TO INCREASE...TIGHTENING SFC
GRADIENT WILL RESULT IN ADVISORY GUSTS...IE TO 60 MPH OR GREATER.
GFS/RAP SHOWING 55-60 KT MTN TOP WINDS LATE TONIGHT...WHICH ALONG
WITH THE STABILITY AND FAVORABLE GRADIENT WILL SUPPORT GUSTS TO 70
MPH. AM CONCERNED GUSTS MAY BE A BIT STRONGER THAN THIS WITH THE
MOST FAVORED TIME PERIOD FROM LATE TONIGHT INTO EARLY SUNDAY
MORNING. WILL MAKE NO CHANGES TO THE ADVISORY ALREADY IN EFFECT.
BIG TIMBER AND HARLOWTON WILL SEE SOME HIGHER GUSTS DURING THE DAY
ON SUNDAY WITH PASSAGE OF WEAK SHORTWAVE. BIG TIMBER SEEMS MOST
FAVORED HERE DUE TO THE SFC GRADIENT AND FLOW ALOFT...AND COULD
SEE GUSTS TO 50-55 MPH. PRESSURE FALLS TO OUR SW BY 18Z WILL WORK
AGAINST THE WIND...ALONG WITH MIXING...SO WILL HOLD OFF ON ANY
HIGHLIGHTS OUTSIDE OF THE GAP AREAS. RED LODGE AND SHERIDAN MAY
ALSO SEE A BRIEF PERIOD OF ENHANCED PREFRONTAL WIND GUSTS
TOMORROW...UP TO 40 MPH...AND HAVE ADJUSTED WIND GRIDS
ACCORDINGLY. GUSTY WINDS WILL CONTINUE AT LVM AND NYE THRU
TOMORROW NIGHT BUT WITH LESS STABILITY AND MID LEVEL FLOW THE
GUSTS SHOULD NOT BE AS HIGH AS TONIGHT AND EARLY SUNDAY.

MILD DAY TODAY WITH TEMPS MOSTLY IN THE 50S. DOWNSLOPE WARMING
WILL CONTINUE TOMORROW AND FEEL 60S ARE A GOOD BET FOR THE FIRST
TIME THIS YEAR...ESPECIALLY CONSIDERING HELP TO MIXING FROM THE
WEAK MID LEVEL SHORTWAVE. CLOUD COVER MAY BE AN ISSUE BUT THE
AIRMASS CERTAINLY WILL SUPPORT 60F+ HIGH TEMPS...SO HAVE ADJUSTED
TEMPS UP A FEW MORE DEGREES. TOMORROW SHOULD BE THE WARMEST DAY IN
BILLINGS SINCE NOVEMBER 19TH.

PCPN CHANCES BEGIN TO INCREASE SUNDAY NIGHT AS PAC TROF APPROACHES
AND MID LEVEL FRONTOGENESIS BEGINS TO INCREASE. MODELS IN GOOD
AGREEMENT HERE. HAVE RAISED POPS 06-12Z MONDAY...WITH HEAVIEST
PCPN EXPECTED MONDAY INTO TUESDAY. SEE EXTENDED DISCUSSION FOR
MORE.

JKL

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

A WET SPRING STORM SYSTEM IS ON TRACK FOR MONDAY THROUGH TUESDAY
MORNING. WITH THIS FORECAST PACKAGE HAVE ISSUED A WINTER STORM
WATCH FOR A PORTION OF THE WESTERN CWA.

MODEL CONSISTENCY REMAINS EXCELLENT WITH THE TIMING AND PLACEMENT
OF THE APPROACHING PACIFIC WAVE. WATER VAPOR IMAGERY INDICATES A
LARGE TAP OF SUBTROPICAL MOISTURE WITH THIS WEATHER SYSTEM...AND
THUS QPF AMOUNTS WILL BE PLENTIFUL ACROSS THE REGION. THE MAJOR
DIFFERENCE WITH THIS STORM FROM THE OTHER WE HAVE SEEN RECENTLY IS
THE LACK OF SIGNIFICANT COLD AIR. SOME MODELS COOL AIR IS
AVAILABLE AND PUSHES INTO THE AREA MONDAY NIGHT...HOWEVER...FOR
MANY LOWER ELEVATION LOCATIONS...PRECIPITATION IS LIKELY TO START
AS RAIN. GIVEN THAT THE MODEL FORECAST 850 MB TEMPERATURES ARE
AROUND +1 TO +2 C BY MONDAY AFTERNOON...THINK THAT A TRANSITION TO
SNOW WILL BE LIKELY FOR LOCATIONS IN THE HEAVIER AREAS OF
PRECIPITATION DUE TO DYNAMICAL COOLING WHICH THE MODELS HANDLE
POORLY. ALSO LOCATIONS ACROSS THE WESTERN PORTION OF THE CWA WILL
SEE A QUICKER TRANSITION TO SNOW DUE THE HIGHER ELEVATION. THE
AMOUNT OF SNOW ANY LOCATION ACROSS THE PLAINS SEES WILL BE VERY
DEPENDENT ON HOW QUICKLY THE TRANSITIONS TO SNOW OCCURS.

OVERALL QPF AMOUNTS ARE QUITE HIGH WITH THIS SYSTEM...WITH MANY
LOCATIONS SEEING HALF INCH TO AN INCH OF LIQUID EQUIVALENT. THUS
THE SNOW WILL ALSO BE A HEAVIER WETTER SNOW THAT WE HAVEN`T SEEN
SINCE THE FALL. ALSO FLOODING CONCERNS ARE INCREASED FOR LOCATIONS
THAT HAVE SEEN FLOODING RECENTLY AS THIS STORM.

GIVEN ALL THIS...HIGHEST SNOW AMOUNTS WILL BE FROM HARLOWTON TO
BILLINGS TO SHERIDAN AND WEST. THE UPSLOPE COMPONENT ALONG WITH
THE MOISTURE TAP AND INSTABILITY IS SOMETHING WE HAVE NOT SEEN IN
THE LAST COUPLE OF STORMS...AND INDICATES THAT THE RED LODGE
FOOTHILLS AND BEARTOOTH FOOTHILLS WILL SEE SOME SIGNIFICANT
ACCUMULATIONS MONDAY NIGHT. THE FLOW REMAINS DOWNSLOPE FOR THEM
DURING THE DAY MONDAY...SO THEY MAY NOT SEE MUCH DURING THE
DAY...BUT ONCE THE 700MB FLOW TURNS TO THE NORTHEAST...THEY WILL
SEE A SIGNIFICANT AMOUNT OF SNOWFALL MONDAY NIGHT.

BEYOND TUESDAY THE WEATHER PATTERN DRIES OUT AND TEMPERATURES WARM
BACK TO SLIGHTLY ABOVE SEASONAL AVERAGES.

CHURCH
&&

.AVIATION...

VFR CONDITIONS WILL PREVAIL OVER THE AREA TONIGHT. SW SURFACE
WINDS WILL INCREASE OVER KLVM TO 30 TO 40 KT WITH GUSTS TO 50 KT
TONIGHT. CHURCH

&&

.PRELIMINARY POINT TEMP/POPS...

    SUN     MON     TUE     WED     THU     FRI     SAT
-----------------------------------------------------------
BIL 040/061 040/045 027/043 028/050 032/052 032/051 034/054
    00/N    39/O    92/O    10/U    00/U    11/B    22/W
LVM 040/057 038/044 024/040 023/048 028/049 029/048 032/050
    02/W    59/O    93/O    10/N    00/N    11/B    22/W
HDN 032/062 035/046 026/044 026/055 030/056 035/053 035/056
    00/B    29/O    92/O    10/U    00/U    11/B    22/W
MLS 033/062 036/049 027/045 028/054 034/053 032/053 034/054
    00/N    16/O    72/O    10/U    00/U    11/B    22/W
4BQ 033/064 035/052 028/042 025/053 032/055 035/052 036/053
    00/N    15/O    92/O    00/U    00/U    11/B    22/W
BHK 031/062 034/049 025/042 027/052 031/051 031/049 032/050
    00/N    05/O    72/O    10/U    00/U    11/B    22/W
SHR 029/063 035/055 026/040 022/052 026/055 028/052 030/053
    00/B    14/O    83/O    10/U    00/U    11/B    22/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WATCH IN EFFECT FROM MONDAY MORNING THROUGH
      TUESDAY MORNING FOR ZONES 40-41-56-64>68.
     WIND ADVISORY IN EFFECT UNTIL 6 AM MDT MONDAY FOR ZONES
      65-66.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS