Area Forecast Discussion
Issued by NWS Glasgow, MT

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000
FXUS65 KGGW 061538 AAA
AFDGGW

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
938 AM MDT WED MAY 6 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH FRIDAY...

SENT AN UPDATE THIS MORNING TO PROVIDE 3-HOURLY GRID SPACING TODAY
AS THE PRECIPITATION TRANSITIONS FROM OUR WESTERN ZONES TO OUR
EASTERN ZONES. QPF ACCUMULATION FORECASTS FOR SOME PLACES WERE
SPOT ON WHILE OTHER WERE TOO MUCH AS IS THE NATURE OF HIT AND MISS
SCATTERED RAIN SHOWERS. MAJORITY OF THE RAIN TODAY IS EXPECTED
VERY NEAR THE EASTERN BORDER OF OUR CWA WHERE A FEW THUNDERSTORMS
ARE ALSO POSSIBLE BUT NOT HIGHLY ANTICIPATED AS MOST OF THE
CONVECTIVE ENERGY IS SHOWN IN THE MODELS TO LINE UP JUST EAST OF
THE BORDER. ALSO EXPECTING QUICK CLEARING BEHIND THE PRECIPITATION
FROM THE WEST LATER TODAY. WILL NEED TO CONSIDER THE POSSIBILITY
OF FOG TONIGHT. WILL TAKE A CLOSER LOOK AND DECIDE WITH THE
AFTERNOON ISSUANCE. LAKE WIND ADVISORY IS SOLID AND WELL IN PLACE
THROUGH THIS EVENING. BMICKELSON

PREVIOUS SHORT TERM DISCUSSION...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...

VFR AT KGGW TODAY BUT MVFR AT KOLF KSDY AND KGDV.

AN AREA OF RAIN WILL MOVE NORTH THROUGH WESTERN NORTH DAKOTA BUT
LOWERING CIGS MAY REACH MVFR CATEGORY THIS AFTERNOON. LIGHT RAIN
SHOWERS SHOULD NOT DRAG VSBYS DOWN TOO MUCH. SHOWERS WILL EXIT
THIS EVENING WITH A RETURN TO VFR CONDITIONS FOR ALL TAF SITES.
NORTHWEST WINDS OF 10-20 KTS ARE EXPECTED AT ALL SITES BY THIS
AFTERNOON. MALIAWCO/TFJ

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 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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