FXUS65 KBYZ 242200
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
300 PM MST THU DEC 24 2009
.SHORT TERM...VALID FOR FRI AND SAT...
UPPER LEVEL MOISTURE MOVING ACROSS WESTERN AND CENTRAL MONTANA
TODAY AND WILL CONTINUE TONIGHT. DID ADD SOME LOW MOUNTAIN POPS
IN FOR TONIGHT IN SATURDAY AS THEY MAY SEE SOME LIGHT SNOW FROM
THIS. LOWER ELEVATIONS WILL BE DRY FROM THIS. WINDS STARTING TO
PICK UP A LITTLE BIT ACROSS THE FAR EAST SO WILL ISSUE A WIND
CHILL ADVISORY UNTIL 12Z FOR THE FAR EAST COUNTIES. LARGE UPPER
LEVEL LOW PRESSURE SYSTEM OVER THE MIDWEST WILL STRENGTHEN
TONIGHT INTO SATURDAY AND WRAP PRECIP BACK INTO EASTERN MONTANA.
THE MODELS CONTINUE TO TRACK FARTHER WEST OVER THE PAST FEW RUNS
WITH THE PRECIP. THEY ALSO KEEP PRECIP INTO SATURDAY WITH THIS
SYSTEM. DO THINK 3 TO 5 INCHES IS A GOOD POSSIBILITY OUT THERE SO
WILL GO AHEAD AND ISSUE A WINTER WEATHER ADVISORY FOR SNOW FOR
THE FOUR EASTERN COUNTIES. DO NOT HAVE CONFIDENCE THAT THE
HEAVIER SNOW WILL GET INTO MILES CITY BUT TO THINK THE EASTERN
PART OF CUSTER COUNTY WILL SEE THE HEAVIER SNOW SO WILL PUT THEM
IN THE ADVISORY. GUSTY WINDS WILL ALSO DEVELOP FRIDAY MORNING AND
CONTINUE INTO SATURDAY SO BLOWING SNOW WILL ALSO BE AN ISSUE.
WILL NEED TO KEEP AN EYE ON THIS OVER THE NEXT 12 TO 24 HOURS TO
SEE IF THERE MAY BE MORE SNOW MOVING INTO THESE AREAS AS WELL AS
STRONGER WINDS. FELT CONFIDENT ABOUT THE ADVISORY BUT NOT
CONFIDENT ENOUGH FOR A WARNING AT THIS TIME. THERE WILL BE A FINE
LINE OF SNOWFALL FROM THIS SO THE SNOW AMOUNTS ARE VERY TRICKY
WITH THIS STORM.
FOR TEMPERATURES...COLD TEMPERATURES WILL CONTINUE TONIGHT AND
LOWERED TEMPS IN A FEW PLACES...ESPECIALLY OUT EAST. WARMER TEMPS
WILL DEVELOP ACROSS THE WEST AND CENTRAL ZONES FRIDAY AND
SATURDAY AS SOUTHWEST WINDS DEVELOP AND PROVIDE SOME WARMING. THE
EAST WILL STAY FAIRLY COLD FRIDAY AND SATURDAY WITH THE PRECIP
MOVING IN. SOLUM
.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
PERIOD BEGINS SUNDAY MORNING WITH THE MAJOR STORM SYSTEM STILL
LINGERING SOUTHERN WISCONSIN. MODELS IN FAIRLY GOOD AGREEMENT WITH
THE LOCATION OF THIS SYSTEM AND AN UPPER LEVEL HIGH PRESSURE
SYSTEM OVER SOUTHWESTERN CANADA. PREVIOUS SHIFT MENTIONED THE
POSSIBILITY OF A TROWAL FEATURE LATER THIS WEEKEND. WHILE THERE IS
A HINT OF A TROWAL FORMING...DECIDED NOT TO INCREASE POPS TO
REFLECT THIS. 295K ISENTROPIC SURFACE DOES NOT SHOW MUCH IN THE
WAY OF MOISTURE TRANSPORT OR LIFT...SO THE NECESSARY MID LEVEL
FORCING MAY NOT BE AVAILABLE TO ENHANCE PRECIPITATION AT THE SURFACE.
AREA WILL BE UNDER THE IMPRESSION OF AN UPPER LEVEL RIDGE
BEGINNING EARLY NEXT WEEK. A FEW DISTURBANCES WILL MAKE THEIR WAY
INTO MONTANA...BUT AT THIS TIME NO MAJOR WEATHER SHOULD BE
ASSOCIATED WITH ANY OF THESE.
THE WIND PATTERN AT 250 MB HAS MOST OF THE STRONGEST FLOW WELL TO
THE NORTHEAST AND SOUTH OF THE NORTHWEST UNITED STATES THROUGH MID
WEEK...WITH MONTANA IN THE BETWEEN TWO UPPER LEVEL LOW PRESSURE
SYSTEMS...ONE TO THE NORTHWEST AND ONE WELL TO THE SOUTH.
HOWEVER A MUCH STRONGER NORTHERLY COMPONENT OF THE JET WILL WORK
ITS WAY INTO WESTERN MONTANA BY NEW YEARS EVE. MODELS ARE
PROJECTING A JET STREAK MAXIMA OF NEAR 110 KNOTS WITH SOUTHWESTERN
MONTANA BEING UNDER THE LEFT EXIT REGION OF THIS JET. THIS COULD
POTENTIALLY BRING SOME FORCING AND VERTICAL MOTION TO THE
AREA...THEREFORE ENHANCING POPS FOR SOME OF THE HIGHER TERRAIN
COME NEW YEARS DAY. WENT AHEAD AND INCREASED POPS FOR LATE NEW
YEARS EVE AND NEW YEARS DAY OVER THE WESTERN ZONES. SINGER
&&
.AVIATION...
CLOUDS HAVE MOVED THROUGH KMLS THIS AFTERNOON AND CLEAR SKIES ARE
PREVAILING. SLIGHT CHANCE FOR SOME SNOW FLURRIES IN THE EASTERN
ZONES TONIGHT...AFFECTING KSHR AND KMLS. PLEASE USE CAUTION IN AND
AROUND THE BIG HORN MOUNTAINS. OTHERWISE...EXPECTING MOSTLY VFR
CONDITIONS FOR THE REST OF THE EVENING AT KBIL AND KLVM. SINGER
&&
.PRELIMINARY POINT TEMP/POPS...
FRI SAT SUN MON TUE WED THU
-----------------------------------------------------------
BIL 000/020 003/028 009/029 013/028 014/030 015/027 012/028
00/B 00/B 01/U 11/B 12/S 22/S 11/B
LVM 002/023 006/030 014/029 015/030 016/030 019/030 019/029
00/B 00/U 01/B 11/B 12/S 22/S 11/B
HDN 903/017 001/024 005/029 008/029 006/029 010/029 005/029
32/S 32/S 01/U 11/B 11/B 22/S 11/B
MLS 910/010 903/017 901/022 004/024 005/024 008/022 005/021
33/S 53/S 01/U 11/B 11/B 11/B 21/B
4BQ 905/013 001/023 002/023 004/028 005/028 008/029 006/023
37/S 86/S 31/B 11/B 12/S 22/S 21/B
BHK 915/007 903/016 000/019 005/023 005/021 007/024 001/019
48/S 96/S 31/B 11/B 12/S 11/B 21/B
SHR 906/017 005/026 006/030 003/030 004/032 007/028 006/029
33/S 43/S 02/S 12/S 22/S 22/S 22/S
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY IN EFFECT FROM 5 AM FRIDAY TO 5 PM
MST SATURDAY FOR ZONES 32-33-36-37.
WIND CHILL ADVISORY IN EFFECT UNTIL 5 AM MST FRIDAY FOR ZONES
33-37.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
