FXUS65 KBYZ 030126
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
626 PM MST WED DEC 2 2009
.SHORT TERM...VALID FOR THU AND FRI...
UPDATE...INCREASED POPS ACROSS MOST OF THE CWA DUE TO
WEBCAMS...RADAR...AND SPOTTER REPORTS OF LIGHT TO MODERATE SNOW
ACROSS MOST OF THE CWA...ESPECIALLY INT THE FOOTHILLS AND EASTERN
ZONES. IR SATELLITE SHOWS ANOTHER SURGE ENTERING NERN MONTANA NOW.
LEACH/CHAMBERS.
LIGHT SNOW/FLURRIES HAVE SPREAD WESTWARD THIS AFTERNOON IN
RESPONSE TO VEERING FLOW WITH ENERGY FROM THE NORTH. LIGHT SNOW
NOW REPORTED AT BILLINGS...AND WEB CAMS SHOW SNOW AT RED LODGE
MOUNTAIN AND IN THE BIG HORNS. LIGHT SNOW ALSO STILL BEING
OBSERVED AT BAKER AND MILES CITY. HAVE RAISED POPS A BIT TONIGHT
TO ACCOUNT FOR ALL OF THIS...BUT THE FAR WEST SHOULD REMAIN DRY.
BIG HORNS ARE FAVORED BY THE CYCLONIC NORTHERLY FLOW BUT
INSTABILITY AND MOISTURE ARE FAIRLY SHALLOW...AND MTN TOP TEMPS
ARE COLDER THAN WHAT IS FAVORED FOR DENDRITES...SO ONLY EXPECT 1-2
INCHES UP NEAR BURGESS JCT TONIGHT. WATER VAPOR IMAGERY SHOWS A
SWD PUSH PERSISTING THROUGH SOUTHERN SASKATCHEWAN...AND THIS
SHOULD ALLOW FOR SOME LIGHT SNOW TO LINGER IN OUR EAST THROUGH
TONIGHT AND PERHAPS MUCH OF THURSDAY. CONDITIONS WILL DRY OUT
FINALLY THURSDAY NIGHT AND FRIDAY AS RIDGING BEGINS TO NOSE IN
FROM THE WEST. FORCING FROM NEXT SHORTWAVE FROM THE NORTH PACIFIC
WILL AFFECT OUR WESTERN PARTS BY FRIDAY NIGHT.
DOWNSLOPE GRADIENTS TIGHTEN THURSDAY NIGHT WITH LEE SIDE TROFFING.
SHOULD SEE ENHANCED WINDS AT LIVINGSTON AND NYE INTO FRIDAY AS A
RESULT. MID LEVEL WINDS DO BACK MORE WESTERLY INTO FRIDAY...
FAVORING THE GAP AREAS...SO THIS WILL NEED TO BE WATCHED...
ESPECIALLY WITH SUCH COLD AIR SETTLING OVER YELLOWSTONE PARK.
TEMPS WILL REMAIN BELOW NORMAL TONIGHT THROUGH THURSDAY NIGHT.
LOWS TONIGHT A BIT TRICKY DUE TO CLOUD COVER AND POTENTIAL MIXING
FROM WIND IN OUR EAST...AND DESPITE THE COLD AIR MASS IN PLACE
THIS MAY KEEP TEMPS FROM FALLING TOO FAR. OUR FAR WEST HAS THE
BEST POTENTIAL FOR RADIATIONAL COOLING AND HAVE DROPPED EXPECTED
LOWS SOME...IN LINE WITH THIS MORNINGS LOWS. SOME HIGH ELEVATION
SITES WERE COLDER THAN -20F THIS MORNING...AND EVEN LIVINGSTON
DROPPED TO ONE BELOW. THURSDAY HIGHS SHOULD BE SIMILAR TO TODAY.
ONSET OF DOWNSLOPING SHOULD MODERATE TEMPS SOME IN OUR WEST
THURSDAY NIGHT...BUT HAVE DROPPED TEMPS IN OUR EAST AS SKIES
SHOULD CLEAR THERE BY THEN. HIGHS FRIDAY SHOULD WARM INTO THE 30S
AS A SW-W WIND DEVELOPS AND 850MB TEMPS WARM TO JUST SLIGHTLY
BELOW ZERO.
JKL
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
RELATIVELY MINOR CHANGES TO THE EXTENDED PERIOD...AS PATTERN
REMAINS INTACT. TROF AXIS APPEARS TO STALL OVER THE CWA ON
SATURDAY...USHERINGIN A REINFORCING COLD PUSH.
DID LOWER TEMPS SLIGHTLY ACROSS THE REGION...THROUGH THE
PERIOD...AS GUIDANCE CONTINUES TO COME IN COLDER...BUT STILL
EXPECT HIGHS TO BE EARLY IN THE DAY ON SATURDAY...WITH COOLING
THROUGH THE DAY. STRONG ARCTIC PUSH WILL RESULT IN HIGHS IN THE
TEENS SUNDAY AND MONDAY. TEMPERATURES START TO TREND SLIGHTLY
UPWARD...TUESDAY AND WEDNESDAY WITH SOME CLEARING...BUT REMAINS A
BIT QUESTIONABLE AT THIS POINT.
RAISED POPS ACROSS THE WESTERN ZONES SATURDAY...WITH POTENTIAL
UPSLOPE. DYNAMICS DO LOOK A BIT BETTER WITH THE GFS...THOUGH
STILL NOT GREAT AT THIS POINT. COLD TEMPS WILL MAKE SNOW GROWTH
MORE DIFFICULT...SO DID HAVE MUCH IN THE WAY OF QPF OR SNOW
ACCUMULATIONS. HAVE KEPT POPS IN ACROSS THE REGION THROUGH MONDAY
NIGHT...AND TAPERING OFF AND SLIDING SOUTH THROUGH THE REMAINDER
OF THE PERIOD. HIGH PRESSURE BECOMES MORE ENTRENCHED... WITH
DECREASING UPSLOPE FLOW. STRONGER NORTHWEST FLOW ALOFT WILL ALSO
CAUSE INCREASING DOWNSLOPE FLOW POTENTIAL. ALSO THERE IS STILL A
BIT OF A QUESTION MARK ON THE OVERALL FLOW AT THIS POINT...WITH
GFS FAVORING MORE NORTHERLY FLOW AND EC FAVORING MORE ZONAL TYPE
FLOW FOR THE END OF THE FORECAST PERIOD. DID KEEP POPS IN THE
HIGH TERRAIN THROUGH THIS PERIOD...BUT MAY NEED TO BE ADJUSTED AS
PATTERN GETS MORE NAILED DOWN. GILSTAD
&&
.AVIATION...
AN ARCTIC LOBE OVER THE AREA WILL BRING MVFR TO OCCASIONAL IFR
CONDITIONS TO MUCH OF THE REGION OVERNIGHT. FAR WESTERN
AREAS...INCLUDING KLVM...WILL LIKELY REMAIN VFR...BUT LOWER
CEILINGS WILL NOT BE FAR TO THE EAST OF THERE. UPSLOPE AREAS FROM
RED LODGE TO SHERIDAN WILL SEE MORE IFR CEILINGS/VIS MOVING IN AND
OUT AS HEAVIER BANDS OF UPSLOPE ENHANCED SNOW MOVE THROUGH.
MOUNTAIN OBSCURATION CAN BE EXPECTED FOR THE BIG HORN AND PRYOR
MOUNTAINS...AS WELL AS THE EASTERN BEARTOOTH/ABSAROKA MOUNTAINS.
CAN'T RULE OUT OCCASIONAL OBSCURATION FOR THE WESTERN
BEARTOOTH/ABSAROKA AND CRAZY MOUNTAINS AS THE CLOUD COVER MAY MAKE
IT INTO THESE AREAS LATE TONIGHT. THESE LOWER CONDITIONS WILL
BEGIN TO IMPROVE THURSDAY MORNING AS THE LOW LEVEL CLOUD COVER
BEGINS TO ERRODE FROM WEST TO EAST. CHAMBERS
&&
.PRELIMINARY POINT TEMP/POPS...
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 008/022 010/035 018/026 007/012 002/014 001/020 006/020
61/B 00/N 14/J 33/J 22/J 21/B 11/B
LVM 902/022 008/032 014/024 903/009 909/013 907/019 004/025
30/U 00/N 23/J 43/J 32/J 21/B 22/S
HDN 008/025 007/036 015/026 006/014 901/016 901/023 006/024
61/B 00/B 03/J 32/J 21/B 21/B 11/B
MLS 010/022 003/033 011/023 004/015 000/016 901/018 002/018
61/B 00/U 12/J 22/J 11/B 21/B 11/B
4BQ 008/020 901/033 010/026 006/016 003/016 003/020 007/023
72/J 00/B 12/J 22/J 21/B 22/J 11/B
BHK 009/018 904/028 007/023 004/017 000/016 003/017 006/020
73/J 00/B 11/B 22/J 11/B 22/J 11/B
SHR 008/022 902/037 014/029 004/014 001/016 004/018 003/023
82/J 00/B 03/J 33/J 32/J 22/J 22/S
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
