FXUS65 KBYZ 160956
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
256 AM MST WED DEC 16 2009
.SHORT TERM...VALID FOR TDY AND THU...
SOUTHWEST WINDS OCCASIONALLY HITTING ADVISORY CRITERIA AT KLVM
TONIGHT...AND RECENT CALL TO STILLWATER MINE SHOWS GUSTS TO 50
MPH. PRESSURE FALLS IN CENTRAL MONTANA ARE INCREASING...AND THE
KIDA-KLWT DIFFERENCE IS UP TO 11MB AS OF 09Z. HAVE ALREADY ISSUED
A WIND ADVISORY FOR THE LIVINGSTON AND NYE AREA...AND AT THIS
POINT SEE NO REASON TO MAKE ANY CHANGES. ADVISORY LEVEL WINDS
SHOULD CONTINUE THROUGH THE 12-18Z TIME FRAME. WINDS SHOULD BEGIN
TO DIMINISH BY LATE AFTERNOON AND EVENING AS MID LEVEL COOL
ADVECTION KICKS IN. BLOWING/DRIFTING SNOW MAY BE AN ISSUE
LOCALLY...BUT TEMPS ARE WELL ABOVE FREEZING ACROSS OUR WESTERN
FOOTHILLS SO DO NOT SEE ANY BIG PROBLEMS ARISING.
SHALLOW COLD AIR LINGERS IN OUR EASTERN VALLEY LOCATIONS...SEE
SINGLE DIGIT READINGS AT KMLS AND KBHK...AND SOME COLD READINGS
ARE NOTED ALONG THE YELLOWSTONE VALLEY A BIT EAST OF BILLINGS. THE
POTENTIAL EXISTS FOR POCKETS OF LIGHT FREEZING RAIN WITH ANY
SHOWER ACTIVITY THAT FORMS TODAY IN RESPONSE TO PACIFIC SHORTWAVE
MOVING ACROSS TO OUR NORTH. WILL NEED TO KEEP WATCH OF THIS...BUT
AT THIS TIME IT APPEARS ANY PRECIPITATION WILL BE LIGHT AS FORCING
IS QUITE WEAK IN OUR AREA AND LOW LEVELS ARE FAIRLY DRY.
MOIST PACIFIC FLOW WILL ALSO FAVOR OUR WESTERN SLOPES FOR SOME
SNOW TODAY/TONIGHT. SHOULD SEE A FEW INCHES AROUND COOKE CITY.
WINDS SHIFT MORE NWLY ON THURSDAY AND THIS WILL SHIFT THE AREAS OF
HEAVIER SNOWFALL. SPEAKING OF THURSDAY...THIS NEXT PACIFIC
SHORTWAVE PROMISES TO BE MORE UNSTABLE AS 500MB TEMPS FALL TO
NEAR -28C. THUS WE SHOULD SEE A GREATER CHANCE OF -RA/SN SHOWERS
ACROSS OUR LOWER ELEVATIONS. HAVE PAINTED HIGHEST POPS ALONG THE
FOOTHILLS AND IN NW FLOW FAVORED AREAS. THE DEVELOPING NW FLOW ON
THURSDAY SHOULD ALSO FAVOR THE BIG HORNS AND HAVE RAISED POPS/SNOW
AMOUNTS THERE. SYSTEM EXITS AND RIDGE BEGINS TO BUILD IN FROM THE
WEST THU NIGHT...SO PCPN SHOULD TAPER OFF THEN.
ARCTIC AIRMASS WILL CONTINUE TO ERODE AWAY TODAY...AND PASSAGE OF
WEAK SHORTWAVE LATE IN THE DAY MAY BE ENOUGH TO SCOUR OUT THE
SHALLOW COLD AIR IN OUR EAST. SHOULD SEE HIGHS INTO THE 40S ACROSS
OUR WEST... AND IN FACT TEMPS ARE AT THAT LEVEL IN SPOTS ALREADY.
BETTER MIXING/NW FLOW ASSOCIATED WITH THURSDAY WAVE SHOULD ALLOW
FOR 40+ READINGS TO SPREAD ACROSS OUR EAST ON THURSDAY. OVERNIGHT
LOWS WILL BE MILD THE NEXT FEW NIGHTS PER SOME WIND/CLOUD COVER.
JKL
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
MODERATING TEMPERATURES TO CONTINUE OVER THE REGION FRIDAY
THROUGH SATURDAY AS A RIDGE OF HIGH PRESSURE ALOFT MOVES SLOWLY
INTO THE AREA FROM THE WEST. NORTHWEST FLOW WILL BE OVER THE
EASTERN ZONES BUT MOISTURE LOOKS LIMITED AND HAVE CONTINUED A DRY
FORECAST. UPPER RIDGE BUCKLES LATE SATURDAY AS A STRONG WAVE
DIVES SOUTH OUT OF BRITISH COLUMBIA THROUGH EASTERN MONTANA.
GFS/ECMWF FAIRLY SIMILAR WITH THIS FEATURE WHICH WILL BRING A
CHANCE OF LIGHT SNOW TO THE EASTERN ZONES. ZONAL FLOW OVER THE AREA
SUNDAY WITH ENERGY MOVING THROUGH THE FORECAST AREA FROM WEST
COAST TROUGH. DOWN SLOPE WINDS OVER THE PLAINS ON SUNDAY FOR DRY
WEATHER BUT THE MOUNTAINS SHOULD SEE A CHANCE OF LIGHT SNOW.
MODELS CONTINUE TO STRUGGLE WITH DEEP TROUGH OVER CANADA FOR
MONDAY THROUGH WEDNESDAY. GFS KEEPS THE TROUGH NORTH INTO CANADA
WHILE THE ECMWF BRINGS IT FURTHER SOUTH AND DEEPENS IT THROUGH
THIS TIME PERIOD. HAVE TRENDED FORECAST TOWARD THE ECMWF SOLUTION
AND BEGAN COOLING TEMPERATURES MONDAY THROUGH WEDNESDAY AS ARCTIC
AIR IS EXPECTED TO MOVE BACK INTO THE REGION. HAVE TRENDED
TEMPERATURES TOWARD MEX GUIDANCE BUT THESE MAYBE TO WARM IF ECMWF
PANS OUT. HAVE CONTINUED SLIGHT CHANCE OF POPS MOST LOCATIONS
DURING THIS TIME PERIOD AS EAST WINDS WILL BRING UPSLOPE FLOW TO
THE PLAINS. THIS SYSTEM COULD BE A SIGNIFICANT SNOW PRODUCER IF
THE ECMWF IS CORRECT. RICHMOND
&&
.AVIATION...
MAIN FLYING HAZARDS TODAY WILL BE STRONG WINDS FROM NYE TO
LIVINGSTON. WINDS OF 30 TO 45 MPH WITH GUSTS TO 60 MPH CAN BE
EXPECTED IN THESE AREAS TODAY THROUGH LATE THIS EVENING. THE
STRONG WINDS COULD PRODUCE MVFR/IFR CONDITIONS DUE TO BLOWING
SNOW. MOUNTAIN OBSCURATIONS CAN ALSO BE EXPECTED TODAY AS SNOW
WILL FALL OVER THE HIGHER ELEVATIONS OF THE BEARTOOTH/ABSAROKA
MOUNTAINS. VFR CONDITIONS ARE EXPECTED FROM KSHR-KBIL-KMLS TODAY.
RICHMOND
&&
.PRELIMINARY POINT TEMP/POPS...
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 042 029/041 022/036 023/038 023/030 024/031 020/028
2/W 02/W 11/B 01/B 11/B 12/S 22/S
LVM 044 032/040 021/034 027/038 025/030 025/033 020/031
2/W 23/W 01/B 11/E 11/B 13/S 32/S
HDN 042 019/042 017/035 013/038 013/030 013/031 011/029
2/W 02/W 21/B 01/B 11/B 11/B 21/B
MLS 034 016/041 016/032 014/035 013/026 012/025 011/024
2/J 02/W 21/B 02/J 21/B 11/B 11/B
4BQ 040 018/041 018/034 016/037 016/027 014/029 014/027
0/B 03/W 31/B 11/B 11/B 11/B 11/B
BHK 034 015/040 016/031 011/032 009/023 008/022 006/022
2/J 02/J 31/B 11/B 21/B 11/B 11/B
SHR 042 018/041 016/035 013/038 014/031 013/031 017/032
0/B 03/W 31/B 01/B 11/B 11/B 12/S
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WIND ADVISORY IN EFFECT UNTIL 11 PM MST THIS EVENING FOR
ZONES 65-66.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
