FXUS65 KBYZ 301054
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
354 AM MST MON NOV 30 2009
.SHORT TERM...VALID FOR TDY AND TUE...
MAIN FORECAST CHALLENGE WITHIN THE SHORT TERM WILL BE WINDS
THROUGH THE FAVORED GAP AREAS OF LIVINGSTON AND HARLOWTON. LEE-
SIDE TROUGHING HAS NOT YET STRONGLY DEVELOPED ACROSS SOUTH
CENTRAL MONTANA. ALTHOUGH PRESSURE RISES CONTINUE BETWEEN IDAHO
FALLS AND LEWISTOWN. INTERESTINGLY THOUGH AS HOURLY PRESSURE
RISES CONTINUE WINDS IN LIVINGSTON HAVE BEEN DECREASING. IN ANY
CASE...EXPECT PRESSURE GRADIENTS TO TIGHTEN TODAY ACROSS THE
UPPER YELLOWSTONE AND STILLWATER VALLEYS. GRADIENT ORIENTATION
STILL NOT OPTIMAL FOR ADVISORY WINDS AS MODELS CONTINUE WITH A
SOUTHWEST/NORTHEAST GRADIENT. STILL BELIEVE WINDS WILL INCREASE
THIS MORNING AND CONTINUE WITH WINDY CONDITIONS INTO THIS
EVENING. WILL HOLD OFF ON A WIND ADVISORY FOR NOW BUT CONTINUE TO
WATCH CLOSELY. THE OTHER WIND CONCERN FOR TODAY IS THE HARLOWTON
AREA WHERE WINDS HAVE BEEN SUSTAINED AROUND 30 MPH AND GUSTING TO
AROUND 40 MPH AT TIMES THIS MORNING. 700MB WINDS TODAY PROGGED TO
BE WESTERLY AROUND 50KTS WITH SOUNDINGS SHOWING AN INVERSION IN
PLACE AS WELL. THIS WILL HELP TO ENHANCE GAP FLOW WINDS ACROSS
THIS AREA AS WELL. CROSS SECTIONS SHOW HIGHER WINDS AT ABOUT 10K
FEET WITH LESSER SPEEDS CLOSER TO THE SURFACE. HAVE INCREASED
WINDS SOME MORE FOR HARLOWTON TO NEAR WARNING CRITERIA AND WILL
HOLD OFF ON ANY HIGHLIGHT AT THIS TIME AS CONFIDENCE NOT HIGH.
FOR TONIGHT...FOCUS SHIFTS TO A STRONG UPPER LEVEL DISTURBANCE
AND COLD FRONT THAT WILL MOVE ACROSS THE FORECAST AREA VERY LATE
TONIGHT INTO TUESDAY MORNING. OVERNIGHT LOWS WILL BE MILD AHEAD
OF THE FRONT AND EXPECT HIGHS ON TUESDAY TO BE REACHED DURING THE
MORNING AND WILL MOST LIKELY BE TONIGHTS LOWS. THE EXCEPTION WILL
BE THE FAR EAST WHERE READINGS MAY BE A FEW DEGREES WARMER THAN
THE LOW TEMPERATURES. VERY GUSTY WINDS WILL BE USHERED IN BEHIND
THE FRONT ESPECIALLY ACROSS THE EASTERN ZONES DURING THE
AFTERNOON AND EARLY EVENING HOURS. STRONG DYNAMICS AND
FRONTOGENESIS BAND MOVE SOUTHEAST ACROSS THE CENTRAL AND WESTERN
ZONES DURING THE DAY TUESDAY WITH THE BULK OF THE DYNAMICS SOUTH
OF OUR AREA BY EVENING. BEST CHANCES FOR SNOW WILL BE ACROSS THE
NORTHWEST FACING SLOPES OF THE BEARTOOTH/ABSAROKA RANGE AND THE
BIG HORNS...AS WELL AS THEIR ADJACENT FOOTHILLS. SEVERAL INCHES
OF SNOW WILL BE LIKELY FOR THE MOUNTAINS WITH A POSSIBLE QUICK
COUPLE OF INCHES FOR THE FOOTHILLS AREAS. SYSTEM LOOKS TO BE
MOVING TOO FAST TO WARRANT HIGHER AMOUNTS. SPEED OF THE SYSTEM
HAS BEEN CONSISTENT THE PAST FEW DAYS BUT IF IT WOULD SLOW DOWN
OR THE FRONTOGENESIS BAND HANGS UP OVER THE FOOTHILLS...HIGHER
AMOUNTS WOULD BE POSSIBLE. MUCH COLDER TEMPERATURES CAN BE
EXPECTED FOR TUESDAY NIGHT WITH READINGS DROPPING DOWN INTO THE
LOWER TEENS ACROSS THE PLAINS. HOOLEY
.LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN...
EXTENDED FORECAST HAS A SOLID POTENTIAL FOR COLDER WEATHER BY THE
WEEKEND BUT THERE DOES NOT APPEAR TO BE A CLEAR PATH TO THIS
TRANSITION. MODELS SHOW DRY NORTHERLY FLOW IN PLACE WITH COOL
SURFACE HIGH PRESSURE IN PLACE ON WEDNESDAY WITH AN UPSTREAM RIDGE
OVER THE PACIFIC NORTHWEST. MOISTURE BEGINS STREAMING OVER THIS
RIDGE INTO THE WESTERN ZONES AND HAVE MOUNTAIN SHOWERS WITH DRY
PLAINS. ECMWF AND GFS DISAGREE ON THE PATTERN FOR THURSDAY AS THE
GFS PUSHES A WEAKENING RIDGE AXIS INTO THE AREA WHILE THE ECMWF
KEEPS A STRONGER CLOSED SYSTEM OVER THE NORTHEAST PACIFIC. GFS
SHOWS DOWNSLOPING AND WARMER TEMPERATURES WHILE THE ECMWF WOULD
KEEP THE COLDER TEMPERATURES. STILL MAINLY DRY EXCEPT FOR MOUNTAIN
SHOWER ACTIVITY AND HAVE TEMPERATURES WARMER THAN WEDNESDAY.
FRIDAY REALLY BECOMES DIFFICULT AS THE GFS PUSHES THE RIDGE EAST
OF THE AREA AND BEGINS DEVELOPING AN UPPER LEVEL WAVE OVER
NORTHWEST MONTANA WHILE THE ECMWF CONTINUES TO LAG THE PACIFIC
SYSTEM FURTHER BEHIND AND NUDGES THE RIDGE INTO THE AREA. HAVE
STUCK WITH A GFS SOLUTION AND KEPT FRIDAY A FAIRLY WELL MIXED DAY
AND INCREASED POPS ESPECIALLY FOR THE SOUTHWESTERN ZONES...AND
BOOSTED WINDS TO REFLECT DOWNSLOPE. SUSPECT THAT THE BEST SOLUTION
WILL BE BETWEEN THE TWO EXTENDED MODELS WITH THE WAVE NOT
PROGRESSING INTO MONTANA QUITE AS QUICKLY AND SUPPORTING A SECOND
DAY OF DOWNSLOPE WITH WARMER MINIMUMS SUPPORTING HIGHER
TEMPERATURES. FOLLOWING THIS BLENDED SOLUTIONS...AREA SHOULD SEE A
FIRST SURGE OF COOLER AIR INTO THE AREA ON SATURDAY WITH POTENTIAL
FOR PRECIP ALONG AND BEHIND THE FRONT DUE TO UPSLOPE BUT MAIN
UPPER LEVEL DYNAMICS SOUTH OF THE AREA. SUNDAY AND MONDAY ARE
CLEARLY COLDER WITH 850 MB TEMPERATURES PROGGED TO BE -10C OR LESS
ON BOTH MODELS AND HAVE REDUCED TEMPERATURES ACCORDINGLY. DOES NOT
LOOK TO BE A LOT OF SNOW POTENTIAL EXCEPT FOR SOME UPSLOPE AS REAL
ACTION LOOKS TO BE OVER THE NORTHERN GREAT BASIN. THERE IS COLD
AIR IN PLACE OVER ALASKA AND EARLY DECEMBER IS A TYPICAL TIME OF
YEAR FOR A SHOT OF THIS AIRMASS TO REACH MONTANA. MAIN MESSAGE IS
THAT WHILE THURSDAY AND FRIDAY WEATHER AND TEMPERATURES ARE NOT
CLEAR CUT...A DRAMATIC TURN TO MUCH COLDER IS EXPECTED THIS
WEEKEND. BORSUM
&&
.AVIATION...
ONLY MID TO HIGH LEVEL CLOUDS EXPECTED ACROSS THE REGION AS UPPER
LEVEL HIGH PRESSURE WEAKENS OVER THE REGION. DEVELOPING LOW
PRESSURE OVER ALBERTA WILL SUPPORT CONTINUED SOUTHWEST WINDS
ESPECIALLY IN FAVORED AREAS ALONG THE BEARTOOTH AND ABSAROKA
FOOTHILLS. A COLD FRONT WILL MOVE INTO THE AREA MONDAY NIGHT
DECREASING THE WINDS BUT BRINGING A CHANCE FOR MOUNTAIN SHOWERS
MAINLY NORTH AND WEST OF KLVM. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
TDY TUE WED THU FRI SAT SUN
-------------------------------------------------------
BIL 053 035/035 015/027 018/035 020/039 020/032 020/022
0/N 04/S 11/B 01/B 11/B 11/B 11/B
LVM 052 034/034 011/025 008/033 011/037 017/030 013/019
0/N 26/S 21/B 11/N 11/B 12/J 22/J
HDN 057 034/034 014/029 017/037 018/041 019/035 018/024
0/B 03/S 21/B 01/B 11/B 11/B 11/B
MLS 054 030/030 015/029 014/034 016/038 018/032 017/021
0/B 02/S 21/B 11/B 11/B 11/B 11/B
4BQ 057 031/031 014/028 013/031 015/038 017/032 016/028
0/B 02/S 21/B 11/B 11/B 11/B 11/B
BHK 051 028/034 015/027 010/030 012/034 012/030 012/021
0/B 02/S 21/B 11/B 11/B 11/B 11/B
SHR 055 028/028 012/027 014/035 018/039 019/032 018/027
0/B 07/S 21/B 11/B 11/B 22/J 22/J
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
