FXUS65 KGGW 120342

AFDGGW



AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE GLASGOW MT

842 PM MST THU MAR 11 2010



.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SATURDAY...

UPDATE...A BAND OF CHINOOK ARCH TYPE HIGH CLOUDS ARE MOVING INTO

NORTHEAST MONTANA AT THIS TIME. THESE HIGH CLOUDS WILL CONTINUE TO

COVER THE AREA IN VARYING AMOUNTS OVERNIGHT. NOT SURE IF THESE

CLOUDS WILL BE THICK ENOUGH TO PREVENT FOG FORMATION OVERNIGHT.

WILL ADD THE BIG MUDDY VALLEY TO THE AREAS OF DENSE FOG OVERNIGHT

WITH PLENTYWOOD RH ALREADY AT 100%. REST OF THE FORECAST LOOKS

REASONABLE AT THIS POINT. FORRESTER



PREVIOUS SHORT TERM...

UPPER RIDGING WILL PUSH IN FROM THE WEST TONIGHT...AND DOMINATE

THROUGH THE SHORT TERM. THIS WILL MAKE FOR DRY CONDITIONS ACROSS

THE WHOLE OF NORTHEAST MONTANA. LIGHT WINDS AND CLEAR SKIES WILL

ALLOW FOG TO RETURN...YET AGAIN...TO NORTHEAST MONTANA TONIGHT.

LOCAL VISIBILITIES WILL LIKELY DIP BELOW 1/2 MILE...ESPECIALLY IN

THE FAVORED MILK AND MISSOURI RIVER VALLEY. 



THE FOG WILL BURN OFF BY AROUND MIDDAY FRIDAY AS CLEAR SKIES ABOVE

THE FOG AND STRATUS ALLOWS THE STRENGTHENING MARCH SUN TO PEAK IN.

CONTINUED A CONSERVATIVE APPROACH REGARDING TEMPERATURES AS AMPLE

FOG AND STRATUS IN THE MORNING...COUPLED WITH STRONG STABILITY

WILL SERVE TO KEEP TEMPS BELOW NORMALS. 



FRIDAY EVENING FOG WILL REDEVELOP. SOUTHEAST WINDS WILL BE ON THE

INCREASE AS A LEE SIDE TROUGH STRENGTHENS TO THE WEST. THIS

SOUTHEASTERLY FLOW AT THE LOW LEVELS MAY HELP KEEP THE FOG FROM

BECOMING TOO DENSE...BUT IF RECENT HISTORY RINGS TRUE IT WILL HAVE

ONLY MINOR INFLUENCE ON FOG FORMATION. 



SATURDAY SOUTHEAST WINDS WILL CONTINUE...AND THE FOG IS AGAIN

EXPECTED TO LINGER THROUGH ABOUT MIDDAY. AN APPROACHING SPLITTING WAVE

FROM THE WEST WILL BRING A FEW CLOUDS INTO THE FAR WESTERN ZONES.

AGAIN WENT CONSERVATIVE REGARDING TEMPS AS LOW LEVEL STABILITY AND

SNOW COVER SHOULD HELP KEEP TEMPS DOWN. GILCHRIST





.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...

AS SO MANY WEATHER SYSTEMS HAVE DONE THIS WINTER...THE NEXT UPPER

LEVEL TROUGH TO HEAD IN OUR DIRECTION SPLITS AROUND US THIS

WEEKEND. THE SOUTHERN WAVE CLOSES OFF AND TAKES MOST STORM

ENERGY WELL TO OUR SOUTH. THE MUCH WEAKER NORTHERN WAVE WILL

MOSTLY AFFECT THE CANADIAN PRAIRIE. THIS SPLIT TROUGH IS QUICKLY

FOLLOWED BY THE NEXT UPPER LEVEL RIDGE AROUND MONDAY. AROUND

THURSDAY OR THURSDAY NIGHT A NARROW WAVE TROUGH WILL TRAVEL EAST

OVER THE NORTHWEST INTRODUCING A COLD FRONT TO OUR AREA. THE GFS

AND ECMWF DIFFER A BIT ON TIMING AND STRENGTH BUT COOLING AND

SLIGHT CHANCE POPS LOOK GOOD FOR DAY 8.



WITH SNOW PACK STILL ON THE GROUND...TEMPERATURES WILL BE THE MAIN

CHALLENGE IN THE EXTENDED PERIOD. WITH CLEARING SKIES TODAY...THE

VISUAL GOES SATELLITE IMAGERY REVEALS SNOW COVERING MOST OF THE

CWA...EXCEPT FOR PETROLEUM AND SOUTHWEST PHILLIPS COUNTIES. BUT

PATCHINESS IS EVIDENT IN THE RIVER VALLEYS. SINCE THE VERNAL

EQUINOX IS ONLY 9 DAYS AWAY...EXPECT THIS PATCHINESS TO EXPAND AS

SNOW CONTINUES TO MELT UNDER RIDGING AND HIGH PRESSURE. ONLY MINOR

CHANGES MADE TO THE EXTENDED FORECAST. SCT



PREVIOUS DISCUSSION...

SIGNS OF SPRING DURING THE PERIOD WITH SOME OF THE WARMEST TEMPS

SO FAR THIS YEAR. UPPER PATTERN HAS ANOTHER SYSTEM APPROACHING FROM

THE WEST THIS WEEKEND TAKING A TURN SOUTHWARD BEFORE IT GETS TO

OUR AREA. AN INVERTED SURFACE TROUGH WITH IT MOVES THRU OUR AREA SAT

NIGHT/SUN MORN...BRINGING A WIND SHIFT AND CLOUDINESS. INVERTED

TROUGH BEHAVES AS A COLD FRONT FOR COOLER TEMPS AND NW WINDS

SUNDAY.



HIGH PRESSURE MOVES ACROSS THE AREA TO BRING CLEARING SKIES AND

LIGHT WINDS BY SUN EVE. THEN STRONG UPPER RIDGING TAKING PLACE

MON/TUE WITH STRONG WARMING ALOFT AND THICKNESSES REACHING 560 DM

BY TUE...850 TEMPS TO 10C. SURFACE PRESSURE GRADIENTS BECOME MORE

FAVORABLY ORIENTED FOR WARMING IN LIGHT SE-S WINDS ALSO. SNOWPACK

STILL A SIGNIFICANT IMPACT ON TEMPS...BUT SHOULD SEE PLENTY OF

MELTING TOO.



MODELS HAVE VARIED A LOT ON THE NEXT SYSTEM APPROACHING FROM THE

W WED...BUT THE TREND IS TO HAVE MORE OF THE ENERGY TO MOVE ACROSS

MT AND S CANADA RATHER THAN FAR TO OUR S AS HAS BEEN THE CASE

LATELY. GFS/GDEX/NOGAPS LEAD THE WAY ON THIS STRONGER N SOLUTION.

ECMWF/GEM MODELS NOT SO CONVINCING...ECMWF LOOKING QUITE CONFUSED

LATELY THOUGH. GFS ENEMBLE MEMBERS INDICATE PLENTY OF DOUBT TOO.

PATTERN OF LATE WOULD INDICATE NEED FOR LEANING TOWARD A DRY AND

WEAKER FRONTAL PASSAGE THAN MOST MODELS SHOW. EXPECT THERE WILL

BE A FRONTAL PASSAGE THOUGH WED...MAINLY DRY WITH A WIND SHIFT AND

INCREASE...AND SOME COOL ADVECTION BEGINNING. A SLIGHT CHANCE OF

SNOW SHOWERS OCCURS WITH UPPER TROUGHING BEHIND THE FRONT

THU...BUT EVEN THAT DOESN'T LOOK LIKE MUCH AT THIS POINT IN TIME.

SIMONSEN





&&



.AVIATION...

VFR TO CONTINUE THROUGH MIDNIGHT. THEN MVFR TO IFR WITH SNOW

PACK...LIGHT WINDS... AND PARTLY CLOUDY SKIES... ADDED FREEZING FOG TO

TERMINAL FORECASTS AGAIN THROUGH FRIDAY MORNING. ONCE FOG BURNS OFF

LATE FRIDAY MORNING... AGAIN EXPECT VFR WITH MOSTLY CLEAR SKIES

AND LIGHT WIND. FREEZING FOG IS A GOOD BET FOR FRIDAY NIGHT. GAH/SCT





&&



.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.



&&



$$



WEATHER.GOV/GLASGOW





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