FXUS65 KBYZ 252210
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
310 PM MST FRI DEC 25 2009
.SHORT TERM...VALID FOR SAT AND SUN...
SNOW OVER THE BEARTOOTH MOUNTAINS AND FOOTHILLS HAS MOSTLY
DISSIPATED THIS AFTERNOON AS THE PRECIP MOVING IN FROM THE STORM
ACROSS THE MIDWEST HAS HAD AN EFFECT ON DISSIPATING THE PRECIP.
SNOW CONTINUES TO PUSH WEST ACROSS THE AREA WITH SNOW AS FAR WEST
AS BIG HORN AND ROSEBUD COUNTIES. CALLS TO THE EASTERN COUNTIES
INDICATE THE FARTHER EAST THE WORSE THE VISIBILITIES AND WORSE
THE SNOW. EKALAKA CAME IN WITH ABOUT 4 INCHES SO FAR WITH LESS AS
YOU GO EAST. SO CURRENT HIGHLIGHTS LOOK PRETTY GOOD AT THIS TIME.
EVENING SHIFT WILL HAVE TO KEEP AN EYE AND MAKE SURE SNOW DOES
NOT GET FARTHER WEST THAN WHAT THE MODELS SHOW. GFS SEEMS TO HAVE
A PRETTY GOOD HANDLE ON CURRENT PRECIP AND WILL FOLLOW THIS MODEL
AND KEEP THE PRECIP EAST OF BILLINGS. SNOW WILL CONTINUE TO PUSH
INTO THE WESTERN AREAS THROUGH THE NIGHT AND START TO TAPER OFF
THROUGH THE DAY SATURDAY AS THE SYSTEM OVER THE MIDWEST SHIFTS
EAST. THE STRONG WINDS ACROSS THE WEST WILL ALSO CONTINUE INTO
SATURDAY AND DECREASE THROUGH THE DAY AS WELL AS THE SYSTEM
SHIFTS EAST. UPPER LEVEL RIDGE WILL START TO BUILD IN FOR
SATURDAY AND SUNDAY AND WILL BRING DRIER AND WARMER CONDITIONS
SPREADING FROM WEST TO EAST INTO SUNDAY. WESTERLY WINDS WILL PICK
UP A LITTLE BIT ACROSS THE WESTERN ZONES AS THE RIDGE BUILDS IN
BUT DO NOT THINK ANY HIGHLIGHTS WILL BE NEEDED AT THIS TIME.
SOLUM
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
EXTENDED FORECAST PERIOD STARTS OFF MONDAY MORNING UNDER THE
INFLUENCE OF AN UPPER LEVEL RIDGE WITH A HIGH PRESSURE SYSTEM
CIRCULATING OVER NORTH CENTRAL ALBERTA. AGREE WITH PREVIOUS SHIFTS
THINKING THAT MINIMUM TEMPERATURES WILL BE LOWER THAN ORIGINALLY
THOUGHT...ESPECIALLY IN FAR EASTERN ZONES...DUE TO THE FRESH SNOW
FROM THE CHRISTMAS DAY STORM.
DOUBLE BARREL PACIFIC TROUGH IS PROJECTED TO HIT THE WEST COAST BY
TUESDAY MORNING. ENSEMBLES ARE IN GENERAL AGREEMENT ON THE
POSITION AND INTENSITY OF THIS TROUGH...WITH A NORTHERN BRANCH OFF
THE PACIFIC NW COAST AND A SOUTHERN BRANCH OFF THE SOUTHERN COAST
OF CALIFORNIA. REAL CONCERN IS HOW LITTLE MOISTURE WILL BE
AVAILABLE TO GENERATE ANY SIGNIFICANT PRECIPITATION. LOWERED POP
FORECASTS FOR TUESDAY AND WEDNESDAY TO REFLECT THIS LACK OF
MOISTURE.
AS THE CHANGING OF THE CALENDAR YEAR APPROACHES...DECIDED TO LOWER
TEMPERATURES FOR THURSDAY AND FRIDAY IN LINE WITH THE EUROPEAN
MODEL. THE ECMWF IS TRENDING MUCH COLDER AT LOWER LEVELS...WITH
850 MB TEMPERATURES OF NEGATIVE 22 WITH PRIMARILY NORTHERLY WINDS
...WELL INTO SOUTHEASTERN MONTANA BY THURSDAY EVENING. GOING TO
GIVE IT ANOTHER COUPLE OF RUNS BEFORE COMPLETELY BUY INTO ECMWF
SOLUTION BEFORE DRAMATICALLY LOWERING TEMPERATURES THAT FAR OUT IN
THE PERIOD. THIS COMBINED WITH CONTINUED SNOW COVER OUT
EAST...HOWEVER...IS BUILDING CONFIDENCE. KEPT CHANCE POP VALUES
IN THERE...AS THERE COULD DEFINITELY BE SOME SNOW POTENTIAL BASED
ON THE AVAILABILITY OF MID LEVEL MOISTURE. VERY INTERESTED IN
SEEING HOW THIS SYSTEM PANS OUT IN FUTURE RUNS. CURRENT GUIDANCE
SUGGESTS THE POTENTIAL FOR SOME ISENTROPIC LIFT SOUTH OF THE
BILLINGS CWA. SINGER
&&
.AVIATION...
VFR CONDITIONS WEST TO VLIFR CONDITIONS EAST DETERIORATING
THROUGHOUT THE EVENING. SNOW FROM THE RETROGRADING LOW OVER THE
MISSOURI RIVER BASIN IS ALREADY IMPACTING KBHK AND KMLS WITH VLIFR
AND LIFR CONDITIONS. BLOWING SNOW WILL BE THE MAIN VISIBILITY
RESTRICTOR. MOST OF THE SNOW AND THE WORST CONDITIONS WILL STAY
EAST OF KBIL...THOUGH THIS EVENING THERE IS A THREAT OF IFR
CONDITIONS AT KBIL WITH LIGHT SNOW. KSHR WILL ALSO REACH LIFR
CONDITIONS TONIGHT DUE TO LIGHT SNOW. KLVM WILL BE VFR TONIGHT.
LEACH/SINGER.
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 003/023 005/029 010/026 013/027 014/025 008/028 011/028
43/S 00/U 01/B 12/S 21/B 11/B 22/S
LVM 006/027 009/029 014/024 015/027 018/027 015/027 018/029
10/B 00/U 01/B 12/S 21/B 12/S 22/S
HDN 001/021 901/029 000/027 005/026 009/026 002/029 004/026
54/S 00/U 00/B 11/B 11/B 11/B 12/S
MLS 903/015 905/022 000/024 004/023 007/018 001/021 004/017
+8/S 00/B 01/U 11/B 11/B 21/B 12/S
4BQ 001/020 902/023 003/025 004/024 007/022 003/024 005/018
++/S 30/B 01/B 12/S 12/S 21/B 22/S
BHK 903/014 907/019 003/022 004/020 006/018 903/016 000/014
++/S 30/B 01/U 12/S 11/B 21/B 12/S
SHR 005/022 007/030 004/028 003/028 006/028 005/029 005/026
+8/S 00/U 01/B 12/S 12/S 22/S 22/S
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY IN EFFECT UNTIL 5 PM MST SATURDAY FOR
ZONES 31-38-58.
WINTER STORM WARNING IN EFFECT UNTIL 5 PM MST SATURDAY FOR
ZONES 32-33-36-37.
WY...WINTER WEATHER ADVISORY IN EFFECT UNTIL 5 PM MST SATURDAY FOR
ZONES 98-99.
&&
$$
WEATHER.GOV/BILLINGS
