FXUS65 KBYZ 050352 AAA
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
852 PM MST SAT FEB 4 2012
.SHORT TERM...VALID FOR SUN AND MON...
BLOCKING PATTERN OVER THE AREA WITH A MID LEVEL HIGH OVER
SOUTHERN CANADA AND A LOW OVER UTAH. OUR AREA WAS IN BETWEEN THE
TWO SYSTEMS AND DOMINATED BY DRIER AIR WITHIN SOME SUBSIDENCE.
SURFACE PRESSURE GRADIENT WAS LIGHT AND THIS HAS ALLOWED
TEMPERATURES TOO FALL QUICKLY THIS EVENING. DEWPOINT TEMPERATURES
IN THE TEENS SHOULD ALLOW READINGS TO FALL MORE TONIGHT. A LEE
TROUGH IS PROGGED TO FORM OVERNIGHT AND THIS WILL CAUSE SOME
INCREASING WINDS OVER CENTRAL AND WESTERN ZONES...WHICH SHOULD
KEEP TEMPERATURES FROM FALLING OFF THE TABLE. DID UPDATE TO DROP
FORECAST LOWS A FEW DEGREES MOST PLACES TONIGHT. TWH
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
MODELS ARE IN RELATIVELY GOOD AGREEMENT THROUGH THURSDAY...THEN
BECOME MORE OUT OF PHASE FRIDAY INTO SATURDAY. AS A RESULT...MADE
MOST OF THE MORE SIGNIFICANT TWEAKS DURING THE TUESDAY TO
THURSDAY TIMEFRAME.
THE EXTENDED PERIOD BEGINS TUESDAY WITH SHORTWAVE ENERGY AND
UPSLOPE FLOW SQUEEZING OUT SOME LIGHT SNOW/SNOW SHOWER ACTIVITY.
SNOW WILL END BY LATE TUESDAY AS MID LEVEL FLOW BECOMES MORE
WESTERLY...INCREASING THE DOWNSLOPE COMPONENT...AND SHORTWAVE
ENERGY WEAKENS/EXITS THE AREA.
WEAK UPPER LEVEL RIDGING MOVES INTO THE REGION EARLY WEDNESDAY
BEFORE A STRONG SHORTWAVE SUPPORTING A SURFACE COLD FRONT DROPS
SOUTHWARD. THE GFS BRINGS THE SHORTWAVE/COLD FRONT COMBINATION
THROUGH THE AREA ABOUT NINE HOURS FASTER THAN DOES THE ECMWF. THE
COLDEST AIR BEHIND THE FRONT LOOKS TO IMPACT EASTERN
MONTANA...BUT SHORTWAVE ENERGY EMBEDDED IN NORTHWEST FLOW
ALOFT...FRONTOGENESIS...AND UPSLOPE FLOW ALL APPEAR TO WORK
TOGETHER TO INCREASE THE POTENTIAL FOR SNOW ACROSS THE WESTERN
TWO-THIRDS OF THE CWA LATE WEDNESDAY NIGHT INTO MID DAY THURSDAY.
TWEAKED WINDS A BIT DURING THIS TIMEFRAME TO SHOW INCREASED
UPSLOPE FLOW AND UPPED POPS A BIT TO ACCOUNT FOR THE POTENTIAL
FOR ENHANCED LIFT THROUGH THE DENDRITIC GROWTH ZONE.
FRIDAY INTO SATURDAY THE GFS IS TRENDING TOWARDS BRINGING A
HIGHLY AMPLIFIED RIDGE INTO THE AREA...WHILE THE ECMWF IS
TRENDING AWAY FROM THE RIDGE SOLUTION...AND NOW FORECASTS A
FAIRLY VIGOROUS SHORTWAVE MOVING ACROSS THE REGION WITH PACIFIC
MOISTURE FRIDAY NIGHT INTO SATURDAY. DUE TO THE MODEL
UNCERTAINTY...MADE NO SIGNIFICANT CHANGES TO THE FRIDAY/SATURDAY
FORECAST. STC
&&
.AVIATION...
VFR CONDITIONS UNDER MAINLY CLEAR SKIES WILL AGAIN PREVAIL ACROSS
THE REGION. PATCHY RIVER VALLEY FOG WILL BE POSSIBLE LATE TONIGHT
AND EARLY SUNDAY MORNING FROM KMLS EAST. AAG
&&
.PRELIMINARY POINT TEMP/POPS...
SUN MON TUE WED THU FRI SAT
-----------------------------------------------------------
BIL 024/051 023/032 014/031 019/041 021/039 026/043 026/049
00/U 02/J 32/J 01/B 22/S 11/B 11/U
LVM 016/049 017/033 016/036 018/041 021/039 026/045 030/046
00/U 01/B 31/B 11/B 23/S 21/B 22/J
HDN 018/053 021/032 015/033 016/041 018/037 022/041 019/047
00/U 02/J 32/J 01/B 12/S 11/B 11/B
MLS 018/049 022/033 013/031 016/038 017/033 020/037 018/044
00/U 02/J 21/B 00/B 11/B 11/B 21/B
4BQ 017/049 022/034 015/031 016/038 017/034 021/038 018/045
00/U 02/J 32/J 01/U 12/S 11/B 22/J
BHK 017/048 020/031 012/027 012/035 013/031 014/035 014/040
00/U 01/B 11/B 01/U 11/U 11/B 21/B
SHR 015/047 018/033 014/034 016/040 018/038 023/042 021/046
00/U 02/J 42/J 11/U 22/S 11/B 21/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
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