000
FXUS65 KBYZ 061046
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
346 AM MST TUE JAN 6 2009
.SHORT TERM...VALID FOR TDY AND WED...
A SLOW PROGRESSIVE PATTERN ACROSS THE US WILL BRING AN EXTENDED
PERIOD OF NORTHWEST FLOW ALOFT TO MONTANA AS AN UPPER LEVEL RIDGE
MOVES THROUGH THE PACIFIC NORTHWEST. WATER VAPOR IMAGERY SHOWS SO
A DEEP PLUME OF MOISTURE MOVING INTO THE WESTERN PART OF THE STATE
AND EXPECT THIS TO MOVE INTO THE WESTERN PORTION OF SOUTHERN
MONTANA LATER THIS MORNING. AT THE SURFACE A TROUGH OVER THE EAST
CENTRAL PART OF MONTANA WILL MOVE LITTLE TODAY AND MOST OF THE
REGION IS ALREADY FAIRLY WELL MIXED WITH TEMPERATURES IN THE LOWER
30S. BETTER DIURNAL COOLING IS OCCURRING OVER THE EASTERN END OF
THE STATE BUT TEMPERATURES IN THE TEENS TO MID 20S ARE INDICATORS
THAT THE ARCTIC AIR IS WANING. FOR TODAY THE MOISTURE BEGINS TO
MOVE INTO THE AREA AND THE STRONG NORTHWEST FLOW ALOFT ALLOWS
ANOTHER ROUND OF SNOW...HEAVY AT TIMES...TO IMPACT THE MOUNTAIN
RANGES. THE NORTHWEST FLOW PATTERN WILL ALLOW THE CRAZY AND BIG
HORN MOUNTAINS TO BE FAVORED MORE THIS GO AROUND ALONG WITH
NORTHWEST FACING ASPECTS IN THE ABASAROKA AND BEARTOOTH
RANGES...WITH A BIT OF A SHADOW FOR THE COOKE CITY AREA. FOR THE
PLAINS EXPECT SOME PRECIP TO TRY AND DEVELOP IN THE SURFACE TROUGH
WHICH WILL LIE BETWEEN BILLINGS AND MILES CITY WITH DOWNSLOPE
LIMITING PRECIP FROM BILLINGS TO THE WEST. HAVE ISSUED A WINTER
STORM WARNING FOR THE MOUNTAIN RANGES STARTING AT NOON TODAY AND
EXPECT ACCUMULATIONS TO REALLY BEGIN PICKING UP TONIGHT. TEMPS
TODAY WILL RISE INTO THE UPPER 30S AND THIS START SUPPORTING A
VARIETY OF PRECIPITATION TYPES ACROSS THE AREA BUT TEMPERATURE
PROFILES INDICATE THAT SNOW SHOULD CHANGE OVER TO RAIN WITH LITTLE
FREEZING RAIN EXPECTED WITH LOW LEVEL WESTERLY WINDS KEEPING LOW
LEVELS WELL MIXED. PRESSURE GRADIENTS FOR GAP FLOW AREAS ARE
ORIENTED TO MUCH ALONG A NORTH TO SOUTH AXIS TO FAVOR GAP FLOW
WINDS TO ACCELERATE TOO MUCH TODAY BUT DO EXPECT BREEZY CONDITIONS
ACROSS MOST OF THE AREA. RIDGE MOVING INTO IDAHO TONIGHT ACTUALLY
STRENGTHENS A BIT IN RESPONSE TO A WAVE OVER BC AND THIS AMPLIFIES
WARM AIR ADVECTION INTO THE REGION. THIS HELPS PROVIDE LIFT AND
WILL CAUSE PRECIPITATION TO INCREASE OVER THE PLAINS WHILE THE
MOUNTAINS CONTINUE TO GET PUMMELED WITH MOISTURE. PHASE OF
PRECIPITATION CONTINUES TO BE A QUESTION OVERNIGHT WITH AN UNKNOWN
AMOUNT OF DIURNAL COOLING POSSIBLY OCCURRING. STILL EXPECT WESTERLY
LOW LEVEL FLOW TO KEEP AIRMASS WELL MIXED AND THINK FREEZING RAIN
WOULD BE VERY BRIEF WITH A RAIN SNOW MIX EXISTING FROM BILLINGS
WEST AND STAYING AS SNOW EAST OF BILLINGS. ACCUMULATIONS IF ANY
WILL BE LIGHT FOR THE LOWER ELEVATIONS...WITH A BIT BETTER
ACCUMULATIONS OVER EASTERN BIG HORN...TREASURE AND ROSEBUD
COUNTIES. WEDNESDAY...TEMPERATURES SHOULD WARM EVEN MORE AS THE
RIDGE PUSHES INTO THE AREA WITH A POSITIVE TILT WHICH ALLOWS LOW
LEVEL FLOW TO BEGIN BACKING AROUND A BIT AND MORE DOWNSLOPISH.
SURFACE TROUGH PULLS TO THE EAST AND WITH TEMPERATURES POSSIBLY
REACHING THE 40S WOULD EXPECT MOST OF SOUTH CENTRAL MONTANA TO
HAVE NO FROZEN PRECIP...WITH SOUTHEAST MONTANA SEEING STRAIGHT
SNOW RESTRICTED TO THE EASTERN BORDER COUNTIES AND POSSIBLY CUSTER
COUNTY. MODELS INDICATE MOISTURE BECOMES LESS FAVORABLE FOR THE
MOUNTAINS BY MID DAY WEDNESDAY AND ACCUMULATIONS WILL DECREASE AS
SNOWFALL RATIOS DECREASE WITH WARMER TEMPERATURES. WINDS ACROSS
THE PLAINS ON WEDNESDAY WILL NEED TO BE WATCHED AS MODELS INDICATE
STRONG 850MB FLOW ACROSS THE AREA BUT UPWARD MOTION WILL OFFSET
SOME OF THE MOMENTUM. WILL HAVE TO WATCH IN THE LEE OF THE CRAZY
MOUNTAINS WHERE BETTER SUBSIDENCE WITH MOUNTAIN WAVE ACTIVITY
COULD ALLOW THE WINDS TO EMERGE. PRECIP SHOULD DECREASE ACROSS
THE AREA WEDNESDAY NIGHT AS THE RIDGE MOVES INTO CENTRAL MONTANA
AND ANOTHER WAVE OF ENERGY MOVING THROUGH BC FURTHER ALLOWS
SURFACE PRESSURE TO DECREASE IN THE CANADIAN ROCKIES. THIS WILL
SET UP THE BEST CHANCE FOR GAP FLOW WINDS RETURNING TO THE
LIVINGSTON AREA BUT MAY NOT MEET ADVISORY CRITERIA UNTIL THURSDAY
MORNING. BORSUM
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
MADE SOME CHANGES TO THE EXTENDED FORECAST THIS MORNING. SOME
WEAK RIDGING WILL BUILD INTO THE AREA ON THURSDAY RESULTING IN A
MOSTLY DRY DAY ACROSS THE PLAINS AND HAVE LOWERED POPS
ACCORDINGLY BUT DID KEEP SOME LOW POPS IN. GUSTY WINDS WILL ALSO
CONTINUE INTO THURSDAY AHEAD OF THE FRONT ACROSS MUCH OF THE AREA
WITH THE STRONGEST WINDS ALONG THE FRONT RANGE. A WARM DAY IS
ALSO IN STORE FOR THURSDAY WITH TEMPS WELL INTO THE 30S AND 40S.
UPPER LEVEL TROUGH WILL SWING THROUGH THE AREA THURSDAY NIGHT AND
INTO FRIDAY. A STRONG COLD FRONT WILL ALSO MOVE ACROSS THE AREA
ON FRIDAY. THIS WILL BRING A STRONG WIND SHIFT TO THE NORTH AND
COLDER TEMPERATURES FOR FRIDAY ALTHOUGH MOST PLACES WILL SEE
TEMPS IN THE 20S AND 30S. THIS TROUGH WILL BRING ANOTHER GOOD
SHOT OF PRECIPITATION TO THE MOUNTAINS WITH SCATTERED SHOWERS
ACROSS THE PLAINS. FLOW TURNS TO AN UPSLOPE FLOW INTO FRIDAY AND
HAVE RAISED POPS ALONG THE SOUTHERN ZONES. DRY NORTHWEST FLOW
WILL SET UP FOR FRIDAY NIGHT THROUGH SATURDAY NIGHT AND HAVE
REMOVED POPS EXCEPT FOR THE MOUNTAINS. TEMPERATURES WILL ALSO
GRADUALLY WARM FOR THIS PERIOD AND KEPT THE TREND GOING. ANOTHER
VERY WINDY PERIOD STILL LOOKS GOOD FOR SUNDAY AS A STRONG
PRESSURE GRADIENT SETS UP ACROSS THE AREA AND HAVE CONTINUED THIS
TREND IN THE FORECAST. ANOTHER OVERRUNNING TYPE OF PATTERN IS
POSSIBLE FOR NEXT MONDAY AND TUESDAY AND HAVE RAISED POPS FOR
THIS. SOLUM
&&
.AVIATION...
GUSTY SOUTHWEST WINDS WILL CONTINUE ALONG THE FRONT RANGE OF THE
BEARTOOTHS AND IN THE KLVM AREA THROUGH THE DAY AND TONIGHT WITH
GUSTS OF 30 TO 40 KNOTS. LIGHT SNOW OVER THE MOUNTAINS THIS
MORNING WILL INTENSIFY THIS AFTERNOON AND BECOME HEAVY SNOW
TONIGHT. THIS WILL RESULT IN WIDESPREAD MOUNTAIN OBSCURATIONS.
ACROSS THE PLAINS...ISOLATED RAIN AND SNOW SHOWERS WILL BE
POSSIBLE THROUGH THE DAY. THE RAIN AND SNOW SHOWERS WILL BECOME
WIDESPREAD ACROSS THE AREA TONIGHT WITH IFR AND MVFR CONDITIONS.
SOLUM
&&
.PRELIMINARY POINT TEMP/POPS...
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 039 029/047 031/049 025/032 018/040 023/042 026/042
2/O 77/O 32/O 42/S 00/B 02/O 23/O
LVM 037 034/047 038/046 027/034 022/037 024/040 028/043
3/O 85/O 33/R 52/S 00/N 02/O 23/O
HDN 040 027/043 027/050 017/033 014/039 018/041 021/044
2/O 77/O 32/O 42/S 00/B 02/O 22/O
MLS 034 018/033 019/046 017/022 009/034 015/036 020/036
2/S 58/S 43/O 42/S 00/B 02/S 22/O
4BQ 037 027/040 030/051 019/027 013/037 018/038 018/038
2/O 67/O 42/O 42/S 00/B 02/O 22/O
BHK 030 014/031 019/044 012/018 006/031 015/032 012/031
2/S 38/S 43/O 42/S 00/B 02/S 22/S
SHR 037 026/046 028/051 018/032 013/039 015/041 021/041
2/O 67/O 32/O 53/S 00/B 02/O 23/O
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING IN EFFECT FROM NOON TODAY TO 12 PM MST
WEDNESDAY FOR ZONES 67-68.
WY...WINTER STORM WARNING IN EFFECT FROM NOON TODAY TO 12 PM MST
WEDNESDAY FOR ZONE 98.
&&
$$
WEATHER.GOV/BILLINGS
