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AREA FORECAST DISCUSSION
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FXUS65 KGGW 090251
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
851 PM MDT FRI MAY 8 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
CONVECTION SOUTHWEST OF A STATIONARY FRONT HAS BEEN DISSIPATING.
ISOLATED TO SCATTERED SHOWERS REMAIN. TEMPS AND CLOUDS APPEAR TO
BE THE GREATEST CHALLENGE AS A SOUTHERN MANITOBA MID LEVEL LOW IS
TRYING TO BRING CLOUDS INTO THE NE ZONES FROM CANADA.
OTHERWISE...CANCELLED LAKE WIND ADVISORY. REST OF FORECAST LOOKED
GOOD. JAMBA
PREVIOUS DISCUSSION...
TONIGHT... RAIN SHOWERS SHOULD GRADUALLY DECREASE ACROSS WESTERN
AND SOUTHWESTERN PORTIONS OF THE CWA AS DRY AIR FROM SASKATCHEWAN
GRADUALLY FILTERS INTO THE REGION ALONG WITH WEAK CAA. WEAK
RIDGING AT 500 MB IS ALSO FORECAST TO ENTER THE REGION ALLOWING
SHOWERS AND CLOUD COVER TO THIN OVERNIGHT.
FRIDAY NIGHT THROUGH SUNDAY...WEAK NORTHWEST FLOW ALOFT AND AN INCOMING
RIDGE WILL SLOWLY RAISE 850MB TEMPERATURES SUPPORT FROM A SPREAD
OF 0*C TO 5*C TO A RANGE OF 5*C TO 10*C ACROSS THE CWA. WHILE MOST
DYNAMICAL SUPPORT WILL BE DISAPPEARING FROM THE REGION... THE NAM
AND GFS COME TO THE RESCUE HINTING AT A SMALL MESOSCALE VORTICITY
MAX ENTERING THE REGION SATURDAY FROM SASKATCHEWAN. THIS VORT MAX
SHOULD ACTIVELY ENHANCE AFTERNOON CONVECTIVE SHOWERS ACROSS THE REGION
AND COULD ALSO HELP TO SPARK A THUNDERSTORM OR TWO. BY SUNDAY HIGH
PRESSURE SHOULD CONTINUE ITS STRANGLEHOLD OVER THE REGION WITH
ONLY ISOLATED AFTERNOON SHOWERS DUE TO INSTABILITY ACROSS THE
REGION. GAH
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
THE LONG TERM SHOULD BEGIN RELATIVELY QUIETLY WITH SOME MODEST
MID-LEVEL RIDGING OVER MOST OF MONTANA SUNDAY AND MONDAY.
GFS AND ECMWF MODELS AGREE REASONABLY WELL IN BRINGING THE NEXT
STORM SYSTEM INTO THE PACIFIC NORTHWEST BY MONDAY EVENING AND
AFFECTING THE NORTHEAST MONTANA AREA WITH DYNAMICAL FORCING. AFTER
MONDAY...THE LATEST RUN OF THE ECMWF MODEL IS NOW MORE IN TUNE
WITH THE GFS...BUT STILL HAS MORE PRECIP. OVER NORTHEAST MONTANA
TUESDAY EVENING. MODEL DIVERGENCE IS MORE SIGNIFICANT THURSDAY AND
FRIDAY WITH GENERALLY SOME RIDGING BUILDING OUT WEST. MARTIN
PREVIOUS LONG TERM DISCUSSION...
MAIN FEATURE OF THE EXTENDED PERIOD IS UPPER LOW/TROF MOVING ALONG
THE MONTANA/CANADIAN BORDER TOWARD THE MIDDLE OF NEXT WEEK. MODELS
CONTINUE TO OFFER DIFFERENT SOLUTIONS ALTHOUGH REASONABLY GOOD
CHANCE OF PRECIPITATION WITH THE SYSTEM AS DEEP SURFACE LOW
DEVELOPS OVER THE NORTHERN PLAINS. BIGGEST QUESTION WITH REGARD TO
THE PRECIP...IS WILL IT BE CONVECTIVE OR STRATIFORM. ANSWER WILL
BE DEPENDENT ON THE TRACK OF THE LOW WITH A MORE NORTHERLY TRACK
FAVORABLE TO CONVECTION. TIGHT PRESSURE GRADIENT AND STRONG COLD
AIR ADVECTION...WITH 850MB TEMPERATURES DROPPING MORE THE 10C ON
TUESDAY...SHOULD RESULT IN WINDY CONDITIONS FOR TUESDAY AND
POSSIBLY WEDNESDAY DAY. COOLER TEMPERATURES ALSO EXPECTED.
DRIER AND WARMER WEATHER EXPECTED AT THE BEGINNING AND END OF THE
PERIOD WITH WEAK RIDGING BRACKETING THE UPPER TROF. EBERT
&&
.AVIATION...
VFR. ISOLATED SHOWERS ARE LINGERING SOUTHWEST OF A MALTA TO
GLENDIVE LINE AS OF 900 PM. ACTIVITY WILL CONTINUE TO DECREASE
THROUGH THE NIGHT. SHOWER ACTIVITY SHOULD PICK UP AGAIN FOR THE
AFTERNOON...IN ABOUT THE SAME LOCATION AS TODAY. LOCAL MVFR
CONDITIONS CAN BE EXPECTED IN AND NEAR SHOWERS. JAMBA
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
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