756
FXUS65 KGGW 091006 CCA
AFDGGW
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE GLASGOW MT
405 AM MDT WED JUL 9 2008
SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH FRIDAY
NORTHWEST FLOW ALOFT THIS MORNING WILL BE REPLACED BY A FLAT RIDGE
TODAY THAT WILL TURN THE FLOW ALOFT ZONAL BY TONIGHT. THIS WILL
BRING A WARMING TREND TODAY AND THURSDAY TO EASTERN MONTANA. WEAK
SHORTWAVES MOVING ALONG THE CANADIAN BORDER THIS AFTERNOON AND
EVENING MIGHT SUCCEED TO PRODUCING A SHOWER OR THUNDERSTORM IN THE NORTHEAST.
WILL MENTION SLIGHT CHANCE POPS FOR NOW.
LOW PRESSURE SYSTEM MOVING THROUGH SOUTHERN SASKATCHEWAN ON THURSDAY
WILL DRAG A FRONTAL SYSTEM ACROSS THE FORECAST AREA IN THE MORNING.
LOOK FOR WEST WINDS...LOW RELATIVE HUMIDITIES AND THE WARMEST
TEMPERATURES OF THE WEEK. WIND WILL LIKELY BE HIGH ENOUGH FOR A
LAKE WIND ADVISORY THURSDAY AFTERNOON.
UPPER LOW IS CURRENTLY OVER THE ALASKA PANHANDLE WILL MOVE
SOUTHEAST INTO BRITISH COLUMBIA TONIGHT AND REACH SASKATCHEWAN BY
FRIDAY MORNING. UPPER TROUGH FROM THE LOW WILL DESCEND ON MONTANA
THURSDAY NIGHT DRAGGING A STRONG COLD FRONT ACROSS THE STATE.
THE FRONT WILL BE DRY FOR THE MOST PART WITH MOST OF THE MOISTURE
STAYING TO THE NORTH CLOSER TO THE UPPER LOW. MAY SEE A
THUNDERSTORM OR TWO ACROSS THE NORTH THURSDAY NIGHT AND IN THE
NORTHEAST HALF OF THE FORECAST AREA ON FRIDAY WHERE VERY STRONG
UPPER LEVEL DYNAMICS WILL MOVE THROUGH. OTHERWISE...IT WILL BE
NOTICEABLY COOLER WITH GUSTY NORTHWEST WINDS ON FRIDAY. FORRESTER
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
ALTERNATING SHORT HOT AND COOLER SPELLS AS THE WESTERLIES REMAIN
FAIRLY ACTIVE FOR JULY. PRECIP CHANCES ARE QUITE LIMITED. THE
LONG TERM PERIOD BEGINS IN A COOL AND DRY FRI NIGHT THUR SAT
NIGHT...NW FLOW BEHIND THE UPPER TROUGH PASSAGE.
AN UPPER TROUGH FROM THE GULF OF AK MOVES SE IN BC...INTENSIFYING
AND DIGGING S SUN AND MON TO PAC NW/S BC BORDER. THIS PUTS NE MT
INTO A BACKING UPPER FLOW FROM THE SW...BRINGING WARM ADVOCATION. A
THERMAL LOW MOVES OVER THE AREA MON...WITH 850 TEMPS 24-28C OVER
OUR AREA AND THICKNESSES WELL INTO THE UPPER 570S DEM. THIS
CONTINUES INTO TUE AND WED. THE BACKING FLOW SLOWS THE APPROACH
OF A COLD FRONT WITH THE THERMAL LOW REMAINING OVER OUR AREA TUE.
SHORTWAVES DURING THIS TIME LOOK WEAK AND THE AIRMASS QUITE
DRY...BUT THAT EXPECTED IN A HOT AIRMASS. WOULD STILL EXPECT AT
LEAST A LITTLE CONVECTION DURING THIS TIME...AND THERE WILL BE
WEAK SURFACE WAVES IN THE THERMAL LOW TO FOCUS ON. MODELS THOUGH
SHOW MEAN RH BELOW 40 PCT...SOMETIMES BELOW 30 PCT IN HOT AIRMASS
DURING THIS TIME...SO NOT EXPECTING A LOT OF STORM COVERAGE. ONE
INTERESTING POSSIBILITY THOUGH IS AN INFLUX OF MOISTURE NORTHWARD
IN THE PLAINS STATES. MODELS MOVE MOST OF THIS INTO ND...BUT
REACHING OUR E IS A REAL POSSIBILITY FOR A SHORT TIME ABOUT LATE MON
NIGHT...WHERE GFS DEW POINTS REACH 55-60F...WHILE REST OF THE AREA
IS MUCH DRIER. WILL RAISE POPS IN OUR E.
MOST MODELS IN GOOD AGREEMENT WITH THE PATTERN...BUT VARYING SOME AS
TO WHETHER THE UPPER TROUGH FROM NW CLOSES OFF AND HOW FAR S IT
REACHES INTO BC AND PAC NW. LATEST ECMWF APPEARS AN OUTLIER AND IS
DISCARDED WITH A MUCH WEAKER SOLUTION. SIMONSEN
AVIATION
VFR WITH SCATTERED LAYERS AT 7K AND 10K FT AGL. ISOLATED MAINLY
THUNDERSTORMS...MAINLY THIS AFTERNOON...WILL HAVE MINOR AND BRIEF
IMPACT ON VISIBILITY. SIMONSEN
GLASGOW WATCHES/WARNINGS/ADVISORIES
NONE.
WEATHER.GOV/GLASGOW
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