579 FXUS65 KBYZ 202123 AFDBYZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BILLINGS MT 323 PM MDT TUE MAR 20 2012 .SHORT TERM...VALID FOR WED AND THU... STRONG WINDS GUSTING TO NEAR 70 MPH CONTINUE FROM LIVINGSTON TO NYE THIS AFTERNOON...AND WIND ADVISORIES REMAIN IN EFFECT FOR THESE AREAS. BLOWING SNOW IN THE LIVINGSTON AREA IS CAUSING SOME LOCAL ROAD CLOSURES AS WELL AS DIFFICULT TRAVEL ON I-90. SWINGLEY ROAD FROM LIVINGSTON TO MISSION CREEK ROAD IS CLOSED DUE TO DRIFTED SNOW. SNOWPLOW CREWS ARE STRUGGLING IN THIS AREA TO KEEP SOME ROADS OPEN AS THE STRONG WINDS DRIFT THEM OVER BEHIND THE PLOWS. WINDS WILL REMAIN STRONG THROUGH MOST OF THE NIGHT. SURFACE PRESSURES WILL RELAX AFTER MIDNIGHT ALLOWING WINDS TO SLOWLY DECREASE TOWARD SUNRISE. CAN'T RULE OUT THE NEED TO EXTEND THE WIND ADVISORIES FURTHER INTO WEDNESDAY MORNING THOUGH. HIGH PROFILE VEHICLES SHOULD CONSIDER AVOIDING THE LIVINGSTON AREA TONIGHT AND OTHER TRAVELERS SHOULD BE PREPARED FOR POOR VISIBILITIES...DANGEROUS CROSSWINDS ALONG WITH SLICK AND DRIFTED OVER ROADS IN THIS AREA INCLUDING I-90 FROM BIG TIMBER THROUGH LIVINGSTON. THE SHORT TERM FORECAST IS PRETTY BENIGN OUTSIDE OF THE WINDS IN THE WESTERN FOOTHILLS. DOWNSLOPE WESTERLY WINDS WILL KEEP PRECIPITATION WEST OF THE DIVIDE THROUGH THURSDAY DESPITE A DECENT FLOW OF MOISTURE OFF THE PACIFIC. KEPT LOW POPS FOR THE WESTERN MOUNTAINS BUT EXPECT ONLY INCREASED PERIODS OF CLOUD COVER FOR THE PLAINS. TEMPERATURES TODAY HAVE BEEN HELD DOWN TODAY BY RESIDUAL SNOWCOVER RESULTING IN EVAPORATIVE AND SUBLIMATION COOLING. THE BLOWING SNOW IN LIVINGSTON HELD TEMPERATURES RIGHT AROUND FREEZING...WITH SUB 50 DEGREE READINGS WEST OF ROSEBUD COUNTY. FAR EASTERN AREAS HAVE WARMED INTO THE UPPER 50S. WITH LESS SNOW COVER OVER THE NEXT FEW DAYS...ALONG WITH A BREAK IN THE PACIFIC MOISTURE FLOW ALOFT DECREASING CLOUD COVER...EXPECT SIGNIFICANTLY WARMER TEMPERATURES OVER THE NEXT COUPLE OF DAYS. HIGHS TOMORROW WILL BE IN THE 60S IN MOST LOCATIONS...WITH 70S FROM BILLINGS EAST ON THURSDAY. THERE IS A BIT OF CONCERN REGARDING FIRE WEATHER FOR AREAS EAST OF A MILES CITY TO BROADUS LINE THURSDAY AFTERNOON. GUSTY SOUTH TO SOUTHEAST WINDS AND TEMPERATURES IN THE MID 70S MAY RESULT IN CRITICAL FIRE CONDITIONS IN THESE AREAS. HOWEVER THE FLOW OUT OF THE SOUTH/SOUTHEAST WILL ALSO BE TRANSPORTING GULF MOISTURE TOWARD THE AREA AND THIS MAY RESULT IN HIGHER RELATIVE HUMIDITY VALUES DURING THE WARMEST PART OF THE DAY MITIGATING THE FIRE THREAT. ELECTED TO HOLD OFF ON ISSUING A FIRE WEATHER WATCH FOR NOW BUT WILL CONTINUE TO MONITOR THIS SITUATION CLOSELY. CHAMBERS .LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE... A SOUTHWESTERLY 500-HPA FLOW CONTINUES IN THE LONG TERM WHILE MEAN RIDGING REMAINS IN PLACE ACROSS THE CENTRAL UNITED STATES. THIS IS COMPLICATED BY 1/ A CUT-OFF 500-HPA LOW BENEATH THE RIDGE...AND 2/ THE LIKELY PASSAGE OF A LONG WAVE TROUGH ACROSS MT BY TUE. WE NEED TO NOTE THAT MODEL-TO-MODEL AND RUN-TO-RUN CONSISTENCY WITH REGARD TO THE TROUGH PASSAGE BY EARLY NEXT WEEK IS LOW...SO CONFIDENCE IN THE FORECAST IS AVERAGE AT BEST. WE THUS LET CONTINUITY RULE A LOT OF THE LONG TERM FORECAST...MAKING FEW CHANGES TO THE GOING IDEAS. THE 12 UTC GUIDANCE CALLS FOR A COLD FRONTAL PASSAGE BY FRI NIGHT. TIMING OF THAT FRONT IS A BIT UNCERTAIN...BUT MORE THAN LIKELY THE PRE-FRONTAL ENVIRONMENT WILL YIELD ANOTHER ROUND OF 70+ F HIGHS IN AT LEAST SOUTHEASTERN MT. BEHIND THAT FRONT...THERE IS A TREND FOR EASTERLY LOW-LEVEL FLOW TO BECOME WELL-ESTABLISHED FOR SAT...WHICH COULD RESULT IN TEMPERATURES MUCH COLDER THAN CURRENTLY ADVERTISED GIVEN 850-HPA READINGS OF ONLY +8 TO +10 C. THIS PERIOD COULD WELL REQUIRE SIGNIFICANT FORECAST ADJUSTMENTS WITH LATER FORECASTS...AS 2-METER TEMPERATURE GUIDANCE HAS HIGHS ONLY NEAR 50 F. THE OVERALL SOUTHWEST FLOW ALOFT IS ENOUGH FOR US TO PAUSE BEFORE MAKING LARGE CHANGES AT THIS POINT THOUGH. WE EXPECT WARM AIR ADVECTION TO TAKE OVER BY SUN AND PROBABLY INTO MON OUT AHEAD OF THE TROUGH. ANOTHER PERIOD OF ABOVE-NORMAL TEMPERATURES SHOULD RESULT. BOTH THE 12 UTC GFS AND ECMWF TAKE A LONG WAVE TROUGH ACROSS MT BY MON NIGHT...BUT THE INITIALLY CUT-OFF MID-LEVEL LOW OVER THE CENTRAL UNITED STATES IS A STRONG SIGNAL FOR A SLOWER SOLUTION THAN WHAT GUIDANCE SHOWS. THE HIGHEST FORECAST POPS ARE THUS IN PLAY ON TUE...EVEN THOUGH IT IS ACTUALLY A DRY DAY BEHIND THE TROUGH IN DETERMINISTIC GUIDANCE. THE 00 AND 12 UTC GFS ENSEMBLES ARGUE FOR SOME PRETTY HIGH POPS IN WHATEVER PERIOD THE TROUGH ENDS UP IMPACTING THE AREA...BUT ENOUGH UNCERTAINTY EXISTS TO KEEP LOW-ELEVATION POPS AROUND 30 PERCENT AT THIS STAGE OF THE GAME. SCHULTZ && .AVIATION... LOCAL IFR AND EVEN LIFR CONDITIONS IN BLOWING SNOW MAY CONTINUE IN THE KLVM AREA THROUGH THE EVENING. THIS EVENT HAS ALREADY OCCURRED LONGER THAN EXPECTED...SO IT IS UNCERTAIN WHEN IT WILL END...BUT A SLOW SETTLING OF THE SNOW SHOULD BE OCCURRING. VFR CONDITIONS WILL CONTINUE ELSEWHERE. STRONG WINDS WILL CONTINUE AT KLVM THROUGH THE EVENING WITH GUSTS TO 50+ KT...BUT THEN THEY WILL LIKELY BE ON THE SLOW DECREASE OVERNIGHT. WIND GUSTS WILL DIMINISH ON THE PLAINS BY MID EVENING. SCHULTZ && .PRELIMINARY POINT TEMP/POPS... WED THU FRI SAT SUN MON TUE ----------------------------------------------------------- BIL 034/064 038/070 040/065 040/058 040/069 042/064 035/056 00/B 00/U 00/B 12/W 21/B 12/W 23/R LVM 028/053 037/064 041/063 036/056 038/066 040/057 033/051 11/N 10/N 11/B 23/W 21/B 22/W 34/R HDN 031/067 033/073 037/070 040/062 036/072 038/067 035/057 00/B 00/U 00/U 12/W 21/B 12/W 23/R MLS 031/067 036/076 039/071 043/061 039/072 042/068 035/056 00/B 00/U 00/U 12/W 21/B 12/W 23/R 4BQ 030/068 036/073 038/074 044/066 041/075 041/070 036/057 00/B 00/N 00/U 12/W 11/B 12/W 23/R BHK 032/066 036/073 038/070 041/061 040/071 041/068 037/053 00/U 00/N 00/U 12/W 21/B 12/W 23/R SHR 029/064 034/070 037/070 039/063 037/071 038/066 033/054 00/B 00/U 00/U 12/W 21/B 12/W 22/R && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...WIND ADVISORY IN EFFECT UNTIL 6 AM MDT WEDNESDAY FOR ZONES 65-66. WY...NONE. && $$ WEATHER.GOV/BILLINGS