FXUS65 KBYZ 052148
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
248 PM MST SAT DEC 5 2009
.SHORT TERM...VALID FOR SUN AND MON...
LITTLE IN THE WAY OF CHANGES FOR THE SHORT TERM PERIOD...WITH THE
WEATHER SYSTEM BEHAVING SOMEWHAT AS EXPECTED. SNOW ACCUMULATIONS
MAY BE A BIT LOWER THAN ORIGINALLY ANTICIPATED...BUT IT STILL
APPEARS AS IF BEST SNOWS ARE ON TRACK FOR THIS AFTERNOON...WITH
SOME HEAVIER BANDS POSSIBLE. WSW AND WWA LOOK ON
TRACK...ESPECIALLY WITH REDUCED VISIBILITIES AND SLICK ROADS
AROUND THE AREA.
COLD AIRMASS MOVING INTO THE AREA IS A BIT SLOW...BUT TEMPS ARE
SLOWLY COMING DOWN AND ARE EXPECTED TO CONTINUE TO DROP THROUGH
THE NIGHT...WITH LITTLE IN THE WAY OF WARM UP FOR SUNDAY. ARCTIC
AIR REALLY APPEARS TO TAKE HOLD AT THIS POINT...BUT OVERALL TEMPS
WILL REALLY DEPEND ON ANY CLEARING THAT OCCURS. HIGHS MONDAY WILL
BE IN THE SINGLE DIGITS ABOVE AND BELOW ZERO. MAINTAINED GOING
TEMPS AS THEY CONTINUE BELOW GUIDANCE...AND PATTERN REMAINS
CONSISTENT.
INHERITED POPS LOOK PRETTY GOOD...DID RAISE POPS ALONG UPSLOPE
AREAS TONIGHT AS SYSTEM SLIPS SOUTH AND MORE EASTERLY FLOW KICKS
IN. SYSTEM LOOKS LIKE IT SHOULD BRING LIGHT SNOW ACROSS THE REGION
THROUGH THE SHORT TERM FORECAST PERIOD AS THE COLD AIR REMAINS IN
PLACE AND MID LEVEL WARM AIR ADVECTION KEEPS SOME MOISTURE
AVAILABLE. GILSTAD
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
CHALLENGES REMAIN WITH THE EXTENT OF THE COLD AIR THROUGH THE END
OF THE WEEK INTO EARLY NEXT WEEKEND. NOT MANY CHANGES MADE TO
GOING FORECAST AS TRENDS REMAINED ON TRACK. MAIN ENERGY LIFTS OUT
OF BASE OF WESTERN TROUGH FROM THE 4-CORNERS AREA AND INTO THE
PLAINS LATE TUESDAY. ANY LINGERING LIGHT SNOW ACROSS THE REGION
SHOULD TAPER OFF BY THEN AS UPSLOPE PATTERN ENDS AND MOISTURE
RETREATS. HIGH PRESSURE AND CLEARING SKIES OVER TOP OF SNOW COVER
COULD RESULT THE COLDEST MORNING OF THIS COLD OUTBREAK FOR TUESDAY.
MAINTAINED TEMPERATURES WELL BELOW ZERO FOR THIS TIME FRAME.
NORTHWEST FLOW CONTINUES THROUGH AT LEAST FRIDAY AND SO RETREAT OF
COLD AIR WILL BE SLOW AS EXPECTED THROUGH THE REST OF THE WEEK.
TRANSITION TO MORE ZONAL FLOW AND A WARMER PACIFIC AIRMASS NOW IN
QUESTION FOR THE END OF THE WEEK INTO NEXT WEEKEND. MEDIUM RANGE
GUIDANCE DIVERGING AT THIS POINT. THE ECMWF STILL TRIES TO BRING
IN A MORE ZONAL PATTERN BY SATURDAY. THE GFS ON THE OTHER HAND HAS
BEEN TRENDED AWAY FROM THE ZONAL PATTERN AND ADVERTISING AN EVEN
STRONGER PUSH OF COLD AIR SOUTH INTO THE REGION INTO NEXT WEEKEND.
IF WE ARE ABLE TO ERODE SOME OF THIS COLD AIR LATE THIS
WEEK...MIGHT BE SHORT LIVED. FRIEDERS
&&
.AVIATION...
PERIODS OF SNOW WILL CONTINUE ACROSS THE REGION THROUGH TONIGHT
WITH WIDESPREAD IFR AND LIFR CONDITIONS AND MOUNTAIN OBSCURATIONS
FROM LOW VISIBILITIES AND CEILINGS. THESE CONDITIONS WILL PERSIST
INTO SUNDAY MORNING FOR MOST AREAS. FRIEDERS
&&
.PRELIMINARY POINT TEMP/POPS...
SUN MON TUE WED THU FRI SAT
-----------------------------------------------------------
BIL 001/003 910/901 912/000 908/012 005/022 015/027 020/029
+6/S 43/S 34/S 11/B 11/B 11/B 11/B
LVM 904/004 917/901 918/002 909/017 007/026 016/030 021/032
+6/S 44/S 23/S 22/S 12/S 22/S 22/S
HDN 003/008 910/005 905/007 908/017 003/023 009/029 013/031
+6/S 32/S 34/S 11/B 11/B 11/B 11/B
MLS 901/009 909/006 911/004 910/010 901/018 006/019 009/023
43/S 22/S 24/S 11/B 11/B 11/B 11/B
4BQ 002/011 906/009 905/010 909/011 001/024 006/026 009/030
64/S 22/S 34/S 11/B 11/B 11/B 11/B
BHK 001/009 908/007 906/005 910/012 000/019 005/019 010/024
32/S 22/S 23/S 11/B 11/B 11/B 11/B
SHR 002/008 910/007 908/008 911/013 901/026 006/031 012/032
+6/S 34/S 34/S 12/S 12/S 22/S 22/S
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING IN EFFECT UNTIL 5 AM MST SUNDAY FOR
ZONES 28-63.
WINTER WEATHER ADVISORY IN EFFECT UNTIL 5 AM MST SUNDAY FOR
ZONES 29-34-35-38>42-56-57-64>66.
WY...WINTER WEATHER ADVISORY IN EFFECT UNTIL 5 AM MST SUNDAY FOR
ZONES 98-99.
&&
$$
WEATHER.GOV/BILLINGS
