000 FXUS65 KGGW 120356 AFDGGW AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 856 PM MST MON FEB 11 2008 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH WEDNESDAY... CLEAR SKIES...LIGHT WINDS...AND FRESH SNOW COVER IN SHALLOW LAYER OF MUCH MODIFIED ARCTIC AIR IS ALLOWING TEMPS TO DROP MORE THAN EARLIER FORECAST. INCREASING MID/HIGH CLOUDS LATER TONIGHT...WITH MODELS INDICATING A SHIFT TO A LIGHT WEST WIND...WILL RESULT IN LOWS OCCURRING EARLY. SIMONSEN PREVIOUS UPDATE...AS PER COORDINATION WITH BYZ AND BIS HAVE UPDATED TO TREND UP POPS ACROSS SOUTHERN WIBAUX AND PRAIRIE COUNTIES LATE TONIGHT...AND ESPECIALLY SUNDAY MORNING. THERE IS DECENT CONSISTENCY BETWEEN THE GFS AND THE NAM DEPICTING A WEAK UPGLIDE REGION ACROSS EAST CENTRAL MONTANA LATE TONIGHT INTO EARLY TUESDAY...THAT COULD MAKE FOR SOME LIGHT SNOWFALL. GILCHRIST PREVIOUS DISCUSSION...SHORT TERM PERIOD BEGINS WITH THE UPPER TROUGH FROM THE WEEKEND MOVING INTO THE CENTRAL PLAINS. AN UPPER RIDGE IS BUILDING OVER THE NORTHERN ROCKIES PLACING NORTHEAST MONTANA IN NORTHWEST FLOW ALOFT. AS THE RIDGE MOVES EAST TONIGHT AND TOMORROW A BACK DOOR FRONT WILL PUSH SOUTH INTO THE NORTHEAST ZONES. WHILE THIS IS OCCURRING A VIGOROUS UPPER TROUGH WILL DIVE INTO THE PACIFIC NORTHWEST. BY TUESDAY NIGHT AND WEDNESDAY THIS TROUGH WILL MOVE ACROSS THE REGION BRINGING ANOTHER ROUND OF SNOW. TONIGHT WILL BE SEASONALLY COOL AS THE NIGHT WILL BEGIN GENERALLY CLEAR. UPSTREAM MID AND HIGH LEVEL CLOUDS WILL BEGIN TO OVERSPREAD THE AREA THIS EVENING AND OVERNIGHT...WHICH SHOULD HAVE A MODERATING AFFECT ON MINIMUM TEMPERATURES. TUESDAY SHOULD FEATURE PASSING MID AND HIGH LEVEL CLOUDS AS THERE IS PLENTY OF UPPER LEVEL MOISTURE STREAMING THROUGH THE UPPER RIDGE. AS THE BACK DOOR FRONT SLIDES INTO THE VICINITY OF THE NORTHEAST ZONES A FEW FLURRIES AND LOWER CLOUDS ARE POSSIBLE. TEMPERATURES SHOULD CONTINUE TO MODERATE ACROSS THE FORECAST AREA. THERE IS NO STRONG WARM AIR ADVECTION...BUT THE OVERALL AIRMASS SHOULD MODERATE A FEW DEGREES. THE EXCEPTION COULD BE THE NORTHEAST ZONES...WHERE MAXIMUM TEMPERATURES MAY BE SIMILAR TO TODAY...DEPENDING ON HOW FAR SOUTH THE BACK DOOR FRONT MOVES. BY TUESDAY NIGHT AND WEDNESDAY A SURFACE LOW TRACKS FROM ALBERTA INTO WESTERN SOUTH DAKOTA. OPERATIONAL MODELS INDICATE THE BEST WARM ADVECTION TO BE ACROSS SOUTHEAST SASKATCHEWAN...WESTERN NORTH DAKOTA...AND FAR NORTHEAST MONTANA TUESDAY NIGHT. AS THE SURFACE LOW MOVES THROUGH THE CWA WEDNESDAY A BANDED FRONTOGENETIC FEATURE SHOULD MOVE THROUGH BRINING ANOTHER ROUND OF SNOW. STRONG COLD ADVECTION BEHIND THE SYSTEM SHOULD PRODUCE FALLING TEMPERATURES AND A STRONG WIND CAUSING AREAS OF BLOWING SNOW AND DANGEROUSLY COLD WIND CHILL VALUES. AJZ .LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY... CONFIDENCE SEEMS TO BE INCREASING A BIT WITH ARCTIC BEING MORE GLANCING FOR WEDNESDAY NIGHT AND THURSDAY...SO RAISED TEMPS AGAIN JUST A BIT. MADE WINDS WEDNESDAY NIGHT A BIT MORE DETAILED AS SYSTEM PULLS OUT OF THE AREA. NEXT SYSTEM TO BRING THE NEXT CHANCE OF PRECIP TO THE AREA LOOKS IT BRINGS A BIGGER THREAT ON SATURDAY THAN FRIDAY NIGHT. HOWEVER WILL WAIT FOR ANOTHER MODEL RUN TO MAKE THIS CHANGE. JAMBA PREVIOUS DISCUSSION... MODELS IN GOOD AGREEMENT FOR MOST OF THE EXTENDED PERIOD ALTHOUGH HAVE WARMED SIGNIFICANTLY FOR EARLY IN THE PERIOD FROM PREVIOUS RUNS. ARCTIC FRONT DROPPING INTO THE REGION WEDNESDAY...WITH MODELS NOT PULLING AS COLD OF AIR INTO NORTHEAST MONTANA AS PREVIOUSLY. WITH ARCTIC TAKING A GLANCING BLOW TO THE REGION HAVE RAISED TEMPERATURES FOR WEDNESDAY NIGHT AND THURSDAY. UPPER RIDGE PUSHES INTO THE STATE ON FRIDAY WITH STRONG WARM AIR ADVECTION AHEAD OF NEXT SHORTWAVE. THIS WAVE...FROM THE PACIFIC...WILL SWEEP ALONG THE CANADIAN BORDER SATURDAY AND SLIDE ANOTHER COLD FRONT INTO THE CWA. AFTER THE SHORTWAVE AT THE BEGINNING OF THE PERIOD...NEXT BEST CHANCE FOR SNOW WILL BE WITH THE SHORTWAVE/FRONT FRIDAY NIGHT AND SATURDAY. EBERT && .AVIATION... MID AND HIGH LEVEL CLOUDS WILL BEGIN TO INCREASE ACROSS THE AREA TONIGHT. THERE IS SOME POTENTIAL FOR MVFR STRATUS TO DEVELOP LATE TONIGHT INTO EARLY TUESDAY. LIGHT WINDS TONIGHT WILL INCREASE TO 10 TO 15 KTS OUT OF THE WEST TUESDAY. JAMBA/GILCHRIST && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW