Area Forecast Discussion
Issued by NWS Glasgow, MT

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000
FXUS65 KGGW 060959
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
359 AM MDT WED MAY 6 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH FRIDAY...
UPPER TROF DIGGING ACROSS THE PACIFIC NORTHWEST AND INTO THE GREAT
BASIN TODAY. SURFACE BOUNDARY NEARLY PARALLEL TO THE UPPER FLOW SO
ONLY SLOWLY MOVING EASTWARD. MOISTURE STREAMING NORTH PRODUCING
MAINLY SHOWERS JUST BEHIND THE BOUNDARY...ALTHOUGH A FEW SMALL
THUNDERSTORMS HAS BEEN POPPING UP AHEAD OF THE IT. SHOWERS
EXPECTED TO DIMINISH SOME THIS MORNING AS THE SHORTWAVE LIFTING
ACROSS THE REGION MOVES INTO CANADA. ANOTHER SHORTWAVE EXPECTED TO
LIFT OUT OF THE CENTRAL ROCKIES LATER TODAY...TO PRODUCE ANOTHER
SURGE OF RAINFALL ACROSS FAR EASTERN MONTANA INTO THE DAKOTAS.

BEHIND THE FRONT...PRESSURE RISES AND COLD AIR ADVECTION WILL HELP
PUSH NORTHWEST WINDS INTO LAKE WIND CRITERIA...SO HAVE ISSUED AN
ADVISORY FOR FORT PECK LAKE FOR THIS AFTERNOON AND EARLY EVENING.
HIGH PRESSURE SPREADS EAST OVERNIGHT AND THURSDAY...WHILE UPPER
TROF SPLITS...CREATING CLOSED LOW OVER THE DESERT SOUTHWEST. THE
NORTHERN STREAM TROF WILL KEEP SLIGHTLY COOLER AIR OVER THE
NORTHERN PLAINS AS IS SLIDES EAST ACROSS CENTRAL CANADA THROUGH
THE END OF THE WEEK. EBERT

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
THE LATEST 00Z GUIDANCE CONTINUES TO SHOW SUPPORT FOR NORTHEAST
MONTANA TO REMAIN UNDER THE INFLUENCE OF A TROUGH FRIDAY NIGHT
INTO SATURDAY. THE CWA WILL BE SPECIFICALLY AFFECTED BY THE
NORTHERN STREAM UPPER TROUGH WITH A CLOSED LOW DEVELOPING ON THE
BASE AS IT EJECTS INTO THE CENTRAL/NORTHERN PLAINS. THIS WOULD
SEEM TO FAVOR THE STEADIEST RAINFALL REMAINING SOUTH OF THE
FORECAST AREA BUT THE TROUGH WILL PROVIDE ENOUGH DYNAMIC FORCING
TO MENTION A SLIGHT CHANCE FOR SHOWERS FOR MUCH OF NORTHEAST
MONTANA DURING THIS PERIOD. WILL KEEP THE HIGHEST POPS ACROSS THE
SOUTHERN ZONES CLOSER TO THE CLOSED UPPER LOW.

GIVEN THE TRACK OF THE SURFACE LOW WELL TO THE SOUTHEAST...LOCATED
OVER EASTERN SOUTH DAKOTA BY ABOUT MONDAY MORNING...ONE THING THAT
WILL BE NOTED IS PERSISTENT EAST TO NORTHEAST WINDS ACROSS THE
REGION THROUGH EARLY NEXT WEEK...BECOMING SOUTHEAST BY THE END OF
THE PERIOD. THE TROUGH IN PLACE WILL ALSO KEEP TEMPERATURES NEAR
OR BELOW SEASONAL AVERAGES.

MONTANA MAY FIND ITSELF ON THE NORTHERN EXTENT OF A SHORTWAVE
UPPER RIDGE BY ABOUT TUESDAY WHICH WOULD ALLOW FOR A DRY PERIOD
AND A SLIGHT WARMING TREND. BY THE END OF THE UPCOMING WEEK
HOWEVER MODEL SOLUTIONS DIVERGE ENOUGH THAT CONFIDENCE DROPS OFF.
ENSEMBLE 500MB HEIGHTS SHOW INCREASING SPREAD WHICH IS FURTHER
INDICATIVE OF REDUCED FORECAST CONFIDENCE BY THE END OF THE
PERIOD. AT THIS TIME WILL TREND POPS TOWARD CLIMATOLOGY AND
MAINTAIN THE SLIGHT WARMING TREND. MALIAWCO

&&

.AVIATION...
SCATTERED SHOWERS AND PERHAPS A THUNDERSTORM MAY AFFECT THE
TERMINALS TODAY. STEADIER SHOWER ACTIVITY MAY BE ACCOMPANIED BY
MVFR CIGS AND REDUCED VSBYS AS WELL. IN ANY EVENT...SHOWERS WILL
EXIT THIS EVENING WITH A RETURN TO VFR CONDITIONS FOR ALL TAF
SITES. NORTHWEST WINDS WILL PERSIST TODAY AT 10-20 KTS. MALIAWCO

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM 11 AM THIS MORNING TO 9 PM MDT THIS
EVENING FOR FORT PECK LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...
CENTRAL AND SOUTHERN VALLEY...GARFIELD...MCCONE...PETROLEUM.

&&

$$

WEATHER.GOV/GLASGOW




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