FXUS65 KBYZ 091009
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
309 AM MST WED DEC 9 2009
.SHORT TERM...VALID FOR TDY AND THU...
WIND CHILLS AND AREAS OF BLOWING SNOW WILL BE THE MAIN WEATHER
IMPACTS OVER OUR FORECAST AREA TODAY AND PROBABLY THURSDAY AS
WELL...MAINLY FROM BILLINGS WEST. WIND CHILL ADVISORY IN PLACE
UNTIL 11 AM TODAY LOOKS GOOD WITH BITTER COLD TEMPERATURES AND
STIFF WESTERLY WINDS SPREADING ACROSS THE FORECAST AREA.
WESTERLY WINDS OF 10 TO 20 MPH...POSSIBLY STRONGER IN THE FAR
WESTERN SECTIONS...WILL SPREAD EAST THROUGH THE DAY. BILLINGS AND
LIVINGSTON ARE EASILY HITTING WIND CHILL ADVISORY EARLY THIS
MORNING. MOST LOCATIONS WILL HAVE DOUBLE DIGITS WELL BELOW ZERO
BY SUNRISE. SECTIONS EAST OF BILLINGS MAY NOT QUITE SEE 10 MPH
WINDS UNTIL MID MORNING WHICH ARE TECHNICALLY NECESSARY TO MEET
CRITERIA...BUT WITH ADVISORY ALREADY OUT WILL NOT SPLIT HAIRS AS
WIND CHILLS WILL STILL EASILY BE WITHIN CRITERIA SO WILL LET
ADVISORY CONTINUE FOR THESE EASTERN AREAS AS WELL. AREAS FROM
BILLINGS WEST WILL BE MOST PRONE TO SEE LOCAL BLOWING SNOW. WILL
CONTINUE TO MENTION THIS IN WIND CHILL ADVISORY AND
FORECASTS...BUT DO NOT FEEL AT THIS TIME IT WILL BE WIDESPREAD
ENOUGH TO MERIT ANY FURTHER HIGHLIGHTS.
AS FOR PRECIPITATION AND SKIES...NORTHWEST CYCLONIC FLOW REMAINS
ENTRENCHED OVER THE FORECAST AREA THROUGH THURSDAY NIGHT. WE HAVE
SOME SHORT WAVE ENERGY MOVING THROUGH THE FLOW THAT IS WORKING ITS
WAY DOWN THE FRONT RANGE OF THE NORTHERN ROCKIES AND WILL AFFECT
OUR FORECAST AREA TODAY. EXPECT TO SEE INCREASING CLOUDINESS. LOW
LEVEL MOISTURE IS LIMITED SO LIGHT SNOW IS GENERALLY ALL WE EXPECT
TO SEE. WILL KEEP POPS LOW SINCE MEASURABLE PRECIPITATION WILL BE
HARD TO COME BY FOR MOST LOCATIONS TODAY.
A CHANCE OF LIGHT SNOW OR FLURRIES WILL CONTINUE THROUGH TONIGHT
AND INTO THURSDAY...BUT WILL NOT BE WIDESPREAD AT ANY POINT IN
TIME OR CONTINUE LONG AT ANY PARTICULAR LOCATION. A MORE
SIGNIFICANT WEATHER FEATURE WILL BE INCREASING WINDS AT GAP FLOW
AREAS AND FOOTHILLS IN THE WEST THURSDAY. PRESSURE GRADIENT
TIGHTENS BY SUNRISE THURSDAY PEAKING AROUND MIDDAY. WEST WINDS 30
TO 35 MPH CAN BE EXPECTED AROUND LIVINGSTON AND COULD BE STRONGER
IF MODELS UNDERESTIMATE COLD AIR IN THE PARK. WE DO NOT YET HAVE
MUCH CRUST ON ANY RECENT SNOWFALL SO LOCAL BLOWING SNOW MAY BE
SIGNIFICANT IMPACT FROM THIS AND NEXT FEW SHIFTS WILL NEED TO
ASSESS THIS MORE CLOSELY FOR THURSDAY. IN ADDITION...WIND CHILL
ADVISORIES OVER ENTIRE LOWER ELEVATIONS MAY BE NECESSARY AGAIN
THURSDAY FOR MUCH OF THE AREA AS WIND SPEEDS REACH 10 TO 20 MPH
WITH TEMPS STILL QUITE COLD.
TEMPERATURES WILL VERY GRADUALLY MODERATE NEXT FEW DAYS AS
CYCLONIC FLOW TURNS A BIT MORE ZONAL AND WINDS KEEP BOUNDARY LAYER
MIXED AT NIGHT. BT
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
UPPER LEVEL FLOW TURNS MORE WESTERLY ON FRIDAY AND FRIDAY NIGHT
AS A LOW PRESSURE SYSTEM OVER SOUTHERN CANADA SLOWLY MOVES SOUTH.
THIS LOW PRESSURE SYSTEM WILL EVENTUALLY KICK OUT TO THE EAST BUT
DOES NOT DO SO UNTIL MONDAY. AS THIS SYSTEM SPINS...SEVERAL WEAK
PIECES OF ENERGY ROTATE THROUGH THE FORECAST AREA BRINGING A
SLIGHT CHANCE OF SNOW. ALSO DURING THIS PERIOD...TEMPS NOW STAY A
LITTLE BIT WARMER THROUGH SATURDAY WITH THE ECMWF A TAD WARMER.
THIS IS A CHANGE FROM PREVIOUS RUNS WHERE THE MODELS BROUGHT THE
COLD IN SATURDAY MORNING. DIFFERENCES CONTINUE TO SHOW UP INTO ON
SUNDAY WHERE THE ECMWF BRINGS ANOTHER COLD SURGE INTO THE AREA
AND ANOTHER ONE ON MONDAY. THE GFS DOES NOT BRING THE FIRST COLD
PUNCH IN BUT BRINGS ON IN ON SUNDAY NIGHT AND MONDAY. EVEN THOUGH
BOTH MODELS BRING IN THE COLD SURGE AT ROUGHLY THE SAME TIME
SUNDAY NIGHT AND MONDAY...THE GFS IS MUCH COLDER WITH IT AND
HANGS ON TO IT LONGER. SO AS A RESULT...JUST MADE SOME MINOR
CHANGES TO THE FORECAST GIVEN THESE MODEL TEMPERATURE
DIFFERENCES. BOTH MODELS CONTINUE TO TRY AND WARM IT UP BY MIDDLE
TO END OF NEXT WEEK. SOLUM
&&
.AVIATION...
VFR CONDITIONS WILL CONTINUE ACROSS MOST ROUTES FOR TODAY. WINDS
WILL INCREASE FROM KBIL AND AREAS WEST WHICH MAY RESULT IN
LOCALIZED AREAS OF BLOWING SNOW. THIS MAY RESULT IN LOCALIZED
AREAS OF MVFR CONDITIONS. A WEAK DISTURBANCE WILL MOVE ACROSS THE
AREA TODAY WHICH WILL BRING SOME LIGHT SNOW WHICH ALSO MAY RESULT
IN LOCALIZED MVFR CONDITIONS AND MOUNTAIN OBSCURATIONS. SOLUM
&&
.PRELIMINARY POINT TEMP/POPS...
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 006 903/013 003/017 006/017 011/023 010/027 019/028
1/M 11/M 20/B 22/S 22/S 22/S 20/B
LVM 005 903/014 008/024 012/026 011/026 013/031 019/034
2/J 22/S 20/N 22/S 22/S 22/S 22/S
HDN 009 904/017 901/023 000/021 006/022 004/027 011/027
1/M 11/M 20/B 22/S 22/S 22/S 20/B
MLS 007 906/012 906/014 905/012 903/015 901/017 005/021
2/J 22/S 20/B 22/S 22/S 22/S 20/B
4BQ 008 905/015 902/021 003/022 005/024 004/026 011/025
1/M 21/M 20/B 22/S 22/S 22/S 20/B
BHK 005 906/010 905/014 901/014 000/013 000/015 000/016
1/M 22/S 20/B 22/S 22/S 22/S 20/B
SHR 008 910/013 904/025 002/026 006/029 005/030 011/033
1/M 21/M 20/B 22/S 22/S 22/S 20/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WIND CHILL ADVISORY IN EFFECT UNTIL 11 AM MST THIS MORNING
FOR ZONES 28>42-56>58-63>66.
WY...WIND CHILL ADVISORY IN EFFECT UNTIL 11 AM MST THIS MORNING
FOR ZONE 99.
&&
$$
WEATHER.GOV/BILLINGS
