FXUS65 KBYZ 241646
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
946 AM MST THU DEC 24 2009
.SHORT TERM...VALID FOR TDY AND FRI...
SEVERAL THINGS GOING ON THIS MORNING. WEAK SHORTWAVE MOVING
ACROSS THE EASTERN ZONES PRODUCING A LOW STRATUS DECK. THIS MAY
EVEN PRODUCE SOME FLURRIES THROUGH THE DAY. DID LOWER POPS IN
THESE AREAS TO 10 POPS AND JUST MENTIONED FLURRIES GIVEN THERE IS
NOT MUCH MOISTURE AND NOT TOO GREAT OF DYNAMICS. WILL GO AHEAD
AND CANCEL THE WIND CHILL ADVISORY THIS MORNING AS WINDS HAVE
DIMINISHED OUT THERE. UPPER LEVEL MOISTURE MOVING IN ACROSS THE
WEST BUT NOT PRODUCING ANY CLOUDS. SO HAVE LOWERED CLOUD COVER
ACROSS THE WESTERN AND CENTRAL ZONES. TEMPERATURES WILL BE VERY
TRICKY TODAY. NAM GUIDANCE STAYING COOLER THAN WHAT THE GFS
GUIDANCE IS SHOWING. PREVIOUS FORECAST LEANED TOWARDS THE NAM
GUIDANCE AND WILL CONTINUE WITH THAT. THE WINDS WILL MAKE THE
TEMPS TRICKY AS GUSTS MAY MAKE TEMPS JUMP UP AND THEN THEY MAY
DROP OFF AS THE WINDS DROP OFF. SO WILL KEEP AN EYE ON THAT.
SOLUM
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
LATEST MODELS INDICATED THE POSSIBILITY OF A TROWAL LINGERING BEHIND
THE DEPARTING STRONG LOW PRESSURE SYSTEM MOVING THROUGH THE UPPER
MIDWEST SAT THROUGH SAT NIGHT. THE LAST FEW RUNS OF THE GFS HAVE
BEEN TRENDING TOWARD THIS SOLUTION AND THE LATEST WRF/ECMWF
SUPPORTED IT AS WELL. DID NOT SEE STRONG LIFT WITH THIS FEATURE AT
THIS TIME...BUT BASED ON LATEST TRENDS...HAVE INTRODUCED LOW POPS
INTO THE FAR EASTERN ZONES SAT THROUGH SAT NIGHT. WILL NEED TO KEEP
AN EYE ON FUTURE MODEL SOLUTIONS TO SEE IF FURTHER ADJUSTMENTS TO
THESE PERIODS WILL BE NEEDED. AN UPPER RIDGE WAS FORECAST TO MOVE
INTO THE AREA FOR SUN AND SUN NIGHT. MOISTURE WAS RATHER SPARSE
UNDER THE RIDGE SO HAVE KEPT POPS LOW AND CONFINED TO THE SOUTHERN
MOUNTAINS.
UPPER RIDGE WILL THEN SHIFT E THROUGH TUE NIGHT AS THE NEXT
PACIFIC SYSTEM WORKS IT/S WAY INLAND. MODELS WERE ADVERTISING AN
ELONGATED SPLITTING TROUGH WITH THE NORTHERN BRANCH MOVING THROUGH
THE FORECAST AREA. MODELS DIFFERED IN DETAILS OF THE FLOW AND
ASSOCIATED MOISTURE SO KEPT POP ADJUSTMENTS MINIMAL.
WED LOOKED UNSETTLED WITH CYCLONIC NW FLOW ALOFT SO WENT NEAR
CLIMATOLOGY POPS OVER MUCH OF THE AREA. WED NIGHT POPS WERE ALSO
NEAR CLIMO AND LOOKED FINE AT THIS POINT AS MODELS WERE NOT IN GOOD
AGREEMENT WITH THE PATTERN.
ONLY TEMPERATURE CHANGES WERE FOR SAT...AS MODELS WERE NOT IN GOOD
AGREEMENT WITH TEMPERATURE PROFILES FOR MUCH OF THE EXTENDED
PERIOD. HAVE LOWERED TEMPS ON SAT BASED ON PROJECTED SOUNDINGS AND
POSSIBLE CLOUDS AND PRECIPITATION WITH THE TROWAL. ARTHUR
&&
.AVIATION...
CEILINGS AT KMLS HAVE LOWERED A LITTLE BIT THIS MORNING WITH A
THIN LINE OF CLOUDS FORMING DIRECTLY OVERHEAD. WOULD NOT BE
SURPRISED IF SOME FLURRIES OR LIGHT SNOW STARTED NEAR KMLS AND
KSHR AS WELL AS PORTIONS OF SOUTHEASTERN MONTANA. KEEP IN MIND
THAT ANY LIGHT SNOW MAY OBSCURE MOUNTAINS...ESPECIALLY NEAR THE
BIG HORNS. OTHERWISE EXPECTING VFR CONDITIONS OVER KBIL AND KLVM
FOR THE REST OF THE DAY. SINGER
&&
.PRELIMINARY POINT TEMP/POPS...
TDY FRI SAT SUN MON TUE WED
-------------------------------------------------------
BIL 015 000/020 003/028 009/033 013/028 014/030 015/028
0/U 20/B 01/B 01/U 11/B 11/B 22/S
LVM 017 002/023 006/030 014/035 015/030 016/030 019/031
0/U 00/B 01/U 01/B 11/B 12/S 22/S
HDN 012 902/017 001/024 005/032 008/029 006/029 010/030
1/M 32/S 20/B 01/U 11/B 11/B 22/S
MLS 007 905/010 903/017 901/026 004/024 005/024 008/023
1/M 33/S 32/S 11/U 11/B 11/B 11/B
4BQ 010 901/013 001/023 002/030 004/028 005/028 008/030
1/M 34/S 42/S 11/B 11/B 11/B 12/S
BHK 003 905/007 903/016 000/025 005/023 005/021 007/025
1/M 46/S 62/S 11/B 11/B 11/B 11/B
SHR 013 905/017 005/026 006/032 003/030 004/032 007/029
1/M 32/S 21/B 12/S 12/S 22/S 22/S
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
