AREA FORECAST DISCUSSION

 
 FXUS65 KGGW 232128
 AFDGGW
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE GLASGOW MT
 228 PM MST MON NOV 23 2009
 
 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH WEDNESDAY...
 MAIN FORECAST IMPACT IN SHORT TERM WILL BE CLIPPER SYSTEM ON TUESDAY.
 CURRENT WATER VAPOR IMAGERY SHOWS STRONG SHORTWAVE TROUGH JUST
 ONSHORE OVER WESTERN BRITISH COLUMBIA. SKIES OVER ERN MT HAVE CLEARED
 WITH SUBSIDENCE BEHIND SHORTWAVE TROUGH AXIS ALONG MT/ND BORDER.
 TEMPS HAVE ACTUALLY BEEN WARMER THIS AFTN WITH DOWNSLOPE WESTERLY
 SURFACE WINDS AND SOME CU HAS BEEN DEVELOPING IN SW ZONES ALONG
 EXITING JET MAX. MID/HIGH CLOUD SHIELD IS BEGINNING TO MOVE ACROSS
 CANADIAN ROCKIES AS CLIPPER SYSTEM EJECTS EAST. CURRENT MODEL TRENDS
 HAVE THE GFS FARTHER SOUTH WITH UPPER/SFC LOW NORTH OF REGINA SASK BY
 00Z WED. THE TIMING OF THE SURFACE FRONT APPEARS TO BE ALONG THE
 MT/CAN BORDER BY 15Z...GGW BY 18Z AND ACROSS THE CWA BY 00Z. THICKNESS
 VALUES DROP 16DM WITH DECENT COLD AIR ADVECTION. NAM MODEL WINDS
 APPEAR LITTLE STRONGER WITH THE FRONT SO HAVE BUMPED UP WINDS A BIT
 AND DROPPED MAX TEMPS A FEW DEGREES. ON WED THE SFC LOW TRACK HAS
 TRENDED A LITTLE FARTHER SOUTH SO HAVE INCLUDED SLIGHT CHC POPS
 ALONG NE CORNER WED 00-06Z AND DROPPED MAX/MIN TEMPS A FEW
 DEGREES. SLA
 
 .LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
 AN UPPER RIDGE WILL BRING MILD AND DRY CONDITIONS FOR
 THANKSGIVING. THE RIDGE WILL BEGIN TO GIVE WAY TO A PACIFIC TROUGH
 ON FRIDAY. UPPER HEIGHTS FALL...BUT THE LOCAL AREA REMAINS IN
 CLOSE PROXIMITY TO A 1000-500MB THICKNESS RIDGE...SO MILD
 TEMPERATURES SHOULD PREVAIL. A WEAK MOISTURE STARVED COLD FRONT
 SLIDES ACROSS THE AREA FRIDAY NIGHT USHERING IN SLIGHTLY COOLER
 TEMPERATURES. A CLIPPER SYSTEM DROPS SOUTHEAST TOWARD THE
 NORTHEAST MONTANA NEXT WEEKEND. 12Z OPERATIONAL MODELS HANDLE THIS
 SYSTEM QUITE DIFFERENTLY. THE GFS AND GEM DROP THE UPPER LOW OVER
 THE DAKOTAS AND DEVELOP AN ARCHING PLUME OF HIGHER THETA-E VALUES
 THAT EXTENDS WESTWARD OVER THE LOCAL AREA HENCE ADVERTISING A
 LIGHT TO MODERATE SNOW EVENT. THE ECMWF KEEPS THE UPPER LOW CENTER
 FARTHER NORTH AND CONCENTRATES THE STRONGER SHORTWAVE ENERGY OVER
 THE SOUTHWEST UNITED STATES. THE ECMWF IS MUCH DRIER AND FAVORED
 AT THIS TIME GIVEN PERSISTENCE. UPPER RIDGING RETURNS FOR EARLY
 NEXT WEEK WITH A WARMING AND DRYING TREND. AJZ
 
 &&
 
 .AVIATION...
 VFR CONDITIONS WILL PREVAIL THROUGH TUESDAY. A CLEAR SKY OVERNIGHT
 WILL GIVE WAY TO A PERIOD OF SCATTERED TO BROKEN CLOUD COVER
 TUESDAY AT OR ABOVE 8K FT AS A COLD FRONT PLOWS THROUGH THE
 REGION. THIS FRONT WILL EXCITE A RATHER GUSTY NORTHWEST WIND
 DURING THE LATE MORNING AND AFTERNOON WITH SPEEDS OF 15 TO 25KT
 WITH OCCASIONAL STRONGER GUSTS. AJZ
 
 &&
 
 .CLIMATE...
 THERE HAS BEEN NO PRECIPITATION AT THE GLASGOW AIRPORT SINCE A
 TRACE WAS RECEIVED ON OCTOBER 28TH. THAT IS A TOTAL OF 25 DAYS AS
 OF NOVEMBER 22ND. THAT TIES THE SECOND LONGEST NUMBER OF DAYS
 WITHOUT ANY PRECIPITATION AT THE GLASGOW AIRPORT. THE RECORD IS 28
 DAYS FROM OCTOBER 20TH THROUGH NOVEMBER 16TH 1987. THERE IS
 CURRENTLY NO RAIN OR SNOW FORECAST UNTIL FRIDAY NIGHT. IF THIS
 HOLDS TRUE...THIS CURRENT DRY STREAK WILL BECOME THE LONGEST ON
 RECORD AT THE GLASGOW AIRPORT. THERE ARE LONGER DRY PERIODS PRIOR
 TO 1948 WHEN OBSERVATIONS WERE TAKEN AT DOWNTOWN GLASGOW. THE
 LONGEST SPAN NOT CORRUPTED BY MISSING DATA WAS A REMARKABLE 46
 DAYS FROM SEPTEMBER 16TH TROUGH OCTOBER 31ST 1906. AJZ
 
 &&
 
 .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
 
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