Area Forecast Discussion
Issued by NWS Glasgow, MT

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KGGW 180249
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
849 PM MDT FRI APR 17 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
A QUIET NIGHT ACROSS NORTHEAST MONTANA WILL FEATURE CLEAR SKIES
WITH LIGHT WINDS AND TEMPERATURES FALLING THROUGH THE UPPER 30S
AND LOW 40S BY MORNING. A CHANGE IN WEATHER IS IN THE CARDS FOR
SATURDAY WITH A COLD FRONTAL PASSAGE...EXPECT A FEW PASSING
SHOWERS THAT WILL LARGELY BE HIT OR MISS...WITH INCREASING GUSTY
WINDS BY THE AFTERNOON HOURS ESPECIALLY. THE LAKE WIND ADVISORY
FOR FORT PECK LAKE IS IN GOOD SHAPE. MALIAWCO

PREVIOUS DISCUSSION...

WATER VAPOR IMAGERY AND 500 MB HEIGHT FIELD SHOWS A DRAMATIC SPLIT
FLOW PATTERN OVER THE COUNTRY WITH NORTHEAST MONTANA FIRMLY UNDER
THE INFLUENCE OF THE NORTHERN STREAM WHICH HAS OUR AREA UNDER A
BROAD UPPER-LEVEL RIDGE. THIS IS JUST ENOUGH TO GIVE US SUNNY
SKIES AND RELATIVELY CALM WINDS TODAY WHICH SHOULD CONTINUE WITH
CLEAR SKIES AND CALM WINDS TONIGHT.

AN UPPER-LEVEL TROUGH WILL AMPLIFY A BIT...AS IT DROP OUT OF THE
CANADIAN ROCKIES...AND PUSH A COLD FRONT THROUGH NORTHEAST
MONTANA ON SATURDAY. MAIN FORECAST CHALLENGE HAS BEEN AND WILL BE
THE FIRE WEATHER CONCERNS CONNECTED WITH THESE STRONGER NORTH AND
NORTHWEST WINDS DURING PEAK HEATING. AS MOST OF THE FRONT WILL
HAVE ALREADY PASSED THROUGH THE AREA BY MID-DAY...THE ISOLATED
FIRE WEATHER THREAT MAY BE CONFINED TO SOME SMALL AREAS NEAR AND
SOUTH OF THE YELLOWSTONE RIVER. WITH THIS ISOLATED AND MARGINAL
THREAT...CHOSE NOT TO LEAD WITH ANY FIRE WEATHER HEADLINES FOR
NOW...BUT RATHER ISSUE AN AFTERNOON FIRE WEATHER FORECAST AND
FIRE WEATHER DISCUSSION WITH THESE POINTS OF EMPHASIS.

REGARDLESS...CHOSE TO ISSUE A LAKE WIND ADVISORY FROM SATURDAY
MORNING THROUGH OVERNIGHT SATURDAY NIGHT. MODEL CONSENSUS IS QUITE
GOOD FOR NORTH AND NORTHWEST WINDS OF 25-35 MPH WITH A FEW HIGHER
GUSTS...AND HINTS AT A BRIEF...HALF-DAY...LULL IN THE GUSTY WINDS
DURING THE MORNING HOURS ON SATURDAY...THEN A RETURN TO GUSTY
WINDS IN EXCESS OF 20 MPH SUNDAY AFTERNOON. AS THIS LATTER PORTION
IS WELL INTO DAY 3 OF THE FORECAST...CHOSE TO LEAD WITH THIS LAKE
WIND ADVISORY ENCOMPASSING ONLY THIS FIRST TIME OF WIND THREAT FOR
NOW.

DURING THE DAY ON SUNDAY...WE FIND OUR CWA IN A NORTH OR NORTHWEST
FLOW ALOFT WITH THE COLDER AIR VERY LIGHT PRECIP EXPECTED OVER
OUR NE ZONES AND WARMER AIR OVER OUR SW ZONES. BMICKELSON


.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
NO MAJOR CHANGES FOR THE EXTENDED PERIOD...WITH MOSTLY DRY AND
MILD WEATHER EXPECTED WITH A BLOCKING PATTERN DEVELOPING. CLOSED
LOW LIFTING OUT OF THE DESERT SOUTHWEST WILL LINGER OVER ONTARIO
THROUGH MOST OF NEXT WEEK. TO THE WEST ANOTHER TROF DIGS ALONG
WITH WEST COAST WITH A VERY SHARP HIGH AMPLITUDE RIDGE OVER THE
NORTHERN/CANADIAN ROCKIES. PERSISTENT NORTHWEST FLOW INTO MONTANA
WILL RESULT IN DRY WEATHER ALTHOUGH UPSLOPE AS HIGH PRESSURE
PUSHES OUT OF CENTRAL CANADA COULD PRODUCE SOME SHOWERS OVER
CENTRAL MONTANA LATE IN THE WEEK. EBERT

PREVIOUS LONG TERM DISCUSSION...THE EXTENDED PERIOD BEGINS SUNDAY
NIGHT WITH 00Z MODEL GUIDANCE SHOWING SUPPORT FOR A BUILDING RIDGE
ACROSS THE WESTERN CONUS AND TROUGH/CLOSED LOW OVER THE UPPER
MIDWEST. THIS PATTERN WILL DRIVE NORTHWEST FLOW ALOFT OVER THE
NORTHERN HIGH PLAINS.

MONDAY TO WEDNESDAY WILL FEATURE AN EASTWARD PROGRESSION OF THE
UPPER RIDGE...LEADING TO INCREASING 500-1000MB THICKNESSES AND
THUS WARMER TEMPERATURES. EXPECT HIGHS GRADUALLY INCREASING BACK
TO THE LOW AND MID 60S BY MIDWEEK THOUGH A FEW 50S NEAR THE
CANADIAN BORDER ARE LIKELY. THIS RIDGE WILL PROBABLY BE
RESPONSIBLE FOR LARGE SCALE SUBSIDENCE AND PROMINENTLY DRY
CONDITIONS ACROSS THE AREA.

WEDNESDAY NIGHT AND BEYOND...00Z GUIDANCE SHOWS MORE VARIANCE
DURING THIS TIME PERIOD. ENSEMBLE 500MB HEIGHTS INCREASE IN SPREAD
WHICH LENDS TO SOME UNCERTAINTY. THE FORECAST FOR THE END OF THE
LONG RANGE HAS POPS TRENDING TOWARD CLIMATOLOGY WITH TEMPERATURES
NEAR SEASONAL NORMALS...AND CAN BE BETTER REFINED AS
PREDICTABILITY IMPROVES. IN GENERAL THE ECMWF/GFS EACH BRING A
NARROW TROUGH INTO THE WESTERN CONUS WITH THE RIDGE TRANSLATING A
BIT FURTHER EAST...BUT HANDLE THIS SOMEWHAT DIFFERENTLY...IN
PARTICULAR WITH REGARD TO LOCATION OF CLOSED LOW. MALIAWCO

&&

.AVIATION...
VFR.

SKIES WILL REMAIN MAINLY CLEAR TONIGHT BUT MID AND HIGH CLOUDS
WILL INCREASE DURING THE MORNING. A COLD FRONT WILL SWEEP ACROSS
THE REGION FROM LATE MORNING THROUGH EARLY AFTERNOON WITH WINDS
TURNING NORTHWEST AND INCREASING. GUSTS TO 40 KTS ARE POSSIBLE. TFJ

&&

.FIRE WEATHER...

SOME ISOLATED HEIGHTENED FIRE WEATHER CONDITIONS MAY BE POSSIBLE
SATURDAY AFTERNOON. THE TIMING OF THE COLD FRONTAL WINDS WILL BE
TRICKY. MOST OF THE FRONTAL PASSAGE IS EXPECTED TO HAVE ALREADY
HAPPENED BEFORE THE HUMIDITY DROPS BELOW 30 TO 25 PERCENT...BUT
OUR SE CORNER ZONES...NEAR AND SOUTH OF THE YELLOWSTONE RIVER MAY
JUST BARELY BECOME DRY AND WARM ENOUGH AHEAD OF THE FRONT TO CAUSE
CONCERN. SINCE THE AFFECTED AREA IS EXPECTED TO BE SMALL AND
ISOLATED IN NATURE...CHOSE NOT TO LEAD WITH ANY FIRE WEATHER
HEADLINES...BUT RATHER RE-ISSUE THE FIRE WEATHER FORECAST THIS
AFTERNOON WITH THIS UPDATED INFORMATION AND SEND ANOTHER E-MAIL
MESSAGE TO OUR FIRE WEATHER PARTNERS.

WITH DRY AND DEAD FUELS STILL NOT GIVING WAY COMPLETELY TO THE
SPRING GREEN-UP...A HUMIDITY OF 25 PERCENT OR LESS AND SUDDEN WIND
SPEEDS OF 25 TO 30 MPH AND GUSTS TO 40 MPH NEAR AND BEHIND THE
COLD FRONT...ANY FIRE START COULD QUICKLY SPREAD TOWARD THE SOUTH
AND SOUTHEAST. NEXT SHIFTS TONIGHT AND SATURDAY SHOULD KEEP A
CLOSE EYE ON EVOLVING FIRE WEATHER CONDITIONS ON SATURDAY.
BMICKELSON

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM 7 AM SATURDAY TO 3 AM MDT SUNDAY FOR
FORT PECK LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND
SOUTHERN VALLEY...GARFIELD...MCCONE...PETROLEUM.

&&

$$

WEATHER.GOV/GLASGOW





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.