FXUS65 KBYZ 260320
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
820 PM MST FRI DEC 25 2009
.SHORT TERM...VALID FOR SAT AND SUN...
NO ADJUSTMENTS TO HIGHLIGHTS THIS EVENING. FORECAST PLAYING OUT
FAIRLY WELL AT THIS TIME. HAVE RAISED SOME OVERNIGHT LOWS IN EAST
AS CLOUD COVER AND 850MB WARM AIR ADVECTION SHOULD PREVENT TEMPS
FROM DROPPING OFF MUCH TONIGHT. WARM AIR IN LIVINGSTON AREA WITH
TEMP PUSHING 40 DEGREES THIS HOUR. WILL RAISE TEMPS IN THIS AREA
AS WELL.
SNOW CONTINUES ACROSS THE EASTERN PORTIONS OF OUR FORECAST AREA.
THE MAIN IMPACT THUS FAR HAS BEEN BLOWING SNOW DUE TO STRONG
NORTHWEST WINDS 20 TO 30 MPH. VISIBILITY HAS BEEN REDUCED IN MOST
AREAS TO UNDER A QUARTER MILE AT TIMES IN THE FAR EAST. CARTER
COUNTY OFFICIALS REPORT ABOUT 4 TO 5 INCHES OF SNOWFALL AND STRONG
WINDS HAVE RESULTED IN UP TO 3 FT DRIFTS...AND HAVE CLOSED HIGHWAY
7 FROM BAKER TO EKALAKA. FALLON COUNTY OFFICIALS REPORT UP TO 4 FT
DRIFTS FROM ABOUT 5 INCHES OF ESTIMATED SNOWFALL. LIGHTER BANDS OF
SNOW PUSHED AS FAR WEST AS THE YELLOWSTONE COUNTY LINE AND SHIFTED
SOUTH AS EXPECTED INTO BIG HORN COUNTY. A FEW INCHES IN MILES CITY
AREA WITH VERY POOR TRAVEL CONDITIONS.
CROSS SECTIONS SHOW MOIST ISENTROPIC LIFT CONTINUES THROUGH TONIGHT
ACROSS THE EAST BEFORE IT BEGINS TO NOTICEABLY DECREASE LATE SATURDAY
MORNING. CARTER AND FALLON COUNTIES WILL CONTINUE TO TAKE THE
BRUNT OF THE STORM WHERE OUR FORECAST AREA IS CONCERNED. TRAVEL IN
FALLON AND CARTER COUNTIES WILL BE VERY DIFFICULT OR IMPOSSIBLE.
LOCAL TRAVEL CONDITIONS ACROSS CUSTER AND POWDER RIVER COUNTIES
WILL NOT BE MUCH BETTER. HOWEVER...APPEARS WINDS WILL GRADUALLY
DECREASE SOMEWHAT OVERNIGHT. I EXPECT MUCH IMPROVED CONDITIONS BY
TOMORROW AFTERNOON...BUT ROADS WILL REMAIN SNOWPACKED AND DRIFTED
OVER.
WILL UPDATE PRODUCTS WITH LATEST OBSERVED INFORMATION AND
EXPECTATIONS. BT
.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...
SNOW FROM THE RETROGRADING LOW OVER THE MISSOURI RIVER BASIN WILL
CONTINUE TO IMPACT KBHK AND KMLS WITH LIFR TO IFR CONDITIONS.
BLOWING SNOW WILL BE THE MAIN VISIBILITY RESTRICTOR.
SNOW...BLOWING SNOW AND LOW CEILINGS WILL CONTINUE TO PRODUCE IFR
TO MVFR CONDITIONS IN THE KSHR REGION. EXPECT VFR CONDITIONS AT
KBIL AND KLVM TONIGHT AS THE LIGHT SNOW AND LOW CEILINGS REMAIN
CONFINED TO EASTERN ZONES. CAMPBELL/TESAR.
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 009/023 005/029 010/026 013/027 014/025 008/028 011/028
33/S 00/U 01/B 12/S 21/B 11/B 22/S
LVM 017/033 009/029 014/024 015/027 018/027 015/027 018/029
10/B 00/U 01/B 12/S 21/B 12/S 22/S
HDN 003/021 901/029 000/027 005/026 009/026 002/029 004/026
54/S 00/U 00/B 11/B 11/B 11/B 12/S
MLS 002/015 905/022 000/024 004/023 007/018 001/021 004/017
+8/S 00/B 01/U 11/B 11/B 21/B 12/S
4BQ 003/020 902/023 003/025 004/024 007/022 003/024 005/018
++/S 30/B 01/B 12/S 12/S 21/B 22/S
BHK 003/014 907/019 003/022 004/020 006/018 903/016 000/014
++/S 30/B 01/U 12/S 11/B 21/B 12/S
SHR 008/022 007/030 004/028 003/028 006/028 005/029 005/026
+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
