000
FXUS65 KGGW 130245
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
845 PM MDT MON MAY 12 2008

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH WEDNESDAY...
SHORTWAVE DROPPING THROUGH NORTH CENTRAL MONTANA THIS EVENING.
STILL SOME SHOWERS ACROSS THE AREA...MAINLY THE WESTERN ZONE SO
HAVE ADJUSTED POPS SLIGHTLY TO ACCOUNT FOR THIS. OTHERWISE
FORECAST LOOKS GOOD. SHOWERS WILL CONTINUE TO WEAKEN WITH LOSS OF
DAYLIGHT AND WAVE DROPPING SOUTH. EXPECT SOME CLEARING LATE
TONIGHT...ALONG WITH DIMINISHING WINDS...TO HELP DROP TEMPERATURES
INTO THE 30S. ONLY MINOR UPDATE PLANNED TO FORECAST. EBERT

PREVIOUS SHORT TERM DISCUSSION...SCATTERED SHOWERS WITH POSSIBLY
A LITTLE THUNDER THIS AFTERNOON AND EVENING SHOULD BE ENDING BY
MIDNIGHT AS A TROUGH EXITS THE REGION TO THE EAST. PRECIPITATION
PROBABILITY IS SUPPRESSED IN THE WAKE OF THIS TROUGH ON TUESDAY AS
RIDGING BEGINS OVER THE PACIFIC NORTHWEST. HOWEVER...SHORTWAVES
EMBEDDED IN THE NORTHWESTERLY FLOW ALOFT ARE FORECAST TO LEAD TO A
REASONABLE CHANCE OF RAIN FOR WEDNESDAY. SURFACE LOW HAS MOVED
EAST INTO THE DAKOTAS LEADING TO NORTHERLY WINDS OF AROUND 15 TO
20 KTS OVER MOST OF THE NORTHEAST MONTANA AREA. AS PRESSURE
GRADIENT MOVES EASTWARD...WINDS SHOULD BE LIGHTER ON TUESDAY AND
FROM THE WEST WITH SOME PICK-UP ON WEDNESDAY DUE TO THE SURFACE
REFLECTION OF SHORTWAVE ACTIVITY ALOFT. WINDS COULD TOP 20KTS LATE
WEDNESDAY AND THE NEED FOR A LAKE WIND ADVISORY SHOULD NOT BE
RULED OUT AT THIS POINT.

WITH DECLINING DEWPOINTS IN NORTHERLY FLOW...TUESDAY MORNING
SHOULD BE COOLER WITH LOWS IN THE MID 30S. HIGH TEMPERATURES
TUESDAY AND WEDNESDAY WILL DEPEND ON SKY COVER. SOME HIGH CLOUDS
INDICATED IN THE GFS LATE TUESDAY SHOULD HOLD HIGHS DOWN INTO THE
MID 60S TUESDAY AND PPT SHOULD KEEP HIGHS IN CHECK FOR WEDNESDAY. WJM

.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
LARGE SCALE PATTERN CHANGE STILL IN STORE FOR THE CONUS THIS
PERIOD AS A L/W UPPER RIDGE NOSES INTO THE LOCAL AREA. RECENT NWP
DATA INDICATE EVEN WARMER 850MB TEMPS BY DAYS FOUR AND FIVE...SO
BUMPED THESE TEMPS UP 3-5 DEGREES MOST PLACES. CONCERN STILL
EXISTS THEREAFTER OVER JUST HOW LONG THIS RIDGE CAN REMAIN INTACT.
LATEST ECMWF MAINTAINS A STRONGER RIDGE PRESENCE BY SUNDAY AND
MONDAY THAN THE GFS AND GEFS...SO HAVE MAINTAINED THE INHERITED
DRY FORECAST FOR NOW. SOME CONCERN ALSO BY HPC THAT MODELS ARE TOO
EAGER IN COLLAPSING THIS FEATURE. MCZ

PREVIOUS LONG TERM DISCUSSION...
THE EXTENDED PERIOD BEGINS WEDNESDAY WITH AN EXITING UPPER
DISTURBANCE IN THE NORTHERLY FLOW ALOFT OVER THE AREA IN BETWIXT
UPPER LOW PRESSURE CENTERED OVER HUDSON BAY AND HIGH PRESSURE OVER
THE WEST COAST AS THE PATTERN OVER NORTH AMERICA BECOMES QUITE
AMPLIFIED. THUS WEDNESDAY NIGHT WILL BE ONE OF DIMINISHING CHANCES
FOR SHOWERS AND CLEARING FROM THE NORTH AS THE DISTURBANCE EXITS.
THURSDAY STILL APPEARS TO BE A TRANSITION DAY AS NORTHERLY FLOW
ALOFT STILL REMAINS BUT THE UPPER HIGH FROM THE WEST BEGINS TO
FLEX SOME MUSCLE OUR WAY. THUS TEMPERATURES ARE LIKELY TO REMAIN A
BIT ON THE COOL SIDE. AS STATED 24 HOURS AGO...STILL COULD BE SOME
VERY LIGHT SHOWERS LINGERING IN NORTHERLY FLOW ALOFT BUT NOT
SIGNIFICANT ENUF THREAT TO MENTION AT THIS POINT. THE REMAINDER OF
THE FORECAST PERIOD THURSDAY NIGHT THRU THE WEEKEND WILL BE A
BATTLE BETWEEN THE WEST COAST RIDGE AND THE EASTERN UNITED STATES
TROF. MODELS THIS EVENING HAVE THE WESTERN RIDGING WINNING ENUF OF
THIS BATTLE TO KEEP US DRY AND SEASONAL TO SLIGHTLY ABOVE. SO IT
APPEARS THE UNSETTLED WEATHER OF LATE WHICH PERSISTS THRU THE
MIDDLE OF THIS WEEK WILL GO ON HIATUS FOR LATE IN THE WEEK INTO
EARLY NEXT WEEK AS A BIG WESTERN RIDGE DOMINATES. AFTER WEDNESDAY
NIGHT IT APPEARS THE NEXT THREAT FOR PRECIPITATION WOULD BE PUT
OFF UNTIL AT LEAST NEXT MONDAY NIGHT OR TUESDAY WHEN THE RIDGE
GETS BEATEN DOWN ENUF TO ALLOW A SYSTEM TO MOVE IN.


&&

.AVIATION...
SCATTERED SHOWERS WITH EMBEDDED MVFR CEILINGS WILL DIMINISH IN
COVERAGE BY THIS EVENING LEAVING VFR CONDITIONS IN PLACE FOR
TUESDAY. EXPECT RESIDUAL VFR CEILINGS TO CLEAR OUT OVERNIGHT AS
GUSTY NORTHWEST WINDS SUBSIDE AND REMAIN AROUND 10 KT INTO TOMORROW.
MCZ

&&

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

&&

$$

WEATHER.GOV/GLASGOW

NWS GGW Office Area Forecast Discussion

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