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 040302 AAA
AFDGGW

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
902 PM MDT MON AUG 3 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH WEDNESDAY...

A FRONTAL BOUNDARY STRETCHES NW TO SE ACROSS CENTRAL AND SOUTHEAST
MONTANA THIS EVENING ALONG A LEE SIDE SURFACE TROUGH. THIS IS THE
FOCUS FOR EVENING RAIN SHOWERS AND THUNDERSTORMS. SOME OF THESE
STORMS MAY DRIFT INTO THE WESTERN COUNTIES OF NORTHEAST MONTANA
LATER TONIGHT. THEREFORE INCREASED POP COVERAGE AND SKY COVER
AFTER MIDNIGHT. SURFACE WIND OVER THE CWA IS SOUTHEASTERLY WITH
THE TROUGH TO OUR WEST. WIND IN THE REGION AROUND MILK RIVER
VALLEY AND FORT PECK LAKE IS ELEVATED ABOVE OTHER AREAS. SO
ADJUSTED EVENING WIND. SCT

PREVIOUS DISCUSSION...
SYNOPTIC SET UP...SHORT TERM BEGINS WITH A HOT HIGH PRESSURE
RIDGE OVER THE WESTERN HALF OF THE CONUS WHICH COMES TO A CREST
OVER ALBERTA. A LARGE COOL CORE TROUGH SETS CENTERED OVER THE THE
CANADIAN SHIELD. NORTHEAST MONTANA LIES BETWEEN THESE TWO LARGE
AIR MASSES ON THE WARMER SIDE OF NORTHWEST FLOW ALOFT. FARTHER
WEST... ANOTHER COLD CORE TROUGH SETS OVER THE COAST OF BRITISH
COLUMBIA.

THIS AFTERNOON THROUGH TONIGHT... CONDITIONS SHOULD REMAIN DRY
THROUGH THE REST OF THIS AFTERNOON AS A LEE SIDE SURFACE TROUGH
BEGINS TO SET UP OFF OF THE FRONT RANGE. THE BC TROUGH WILL DROP
SOUTH INTO THE PACIFIC NORTHWEST AND AS IT MOVES THE RIDGE AXIS
WILL GIVE WAY BY DRIFTING INTO EASTERN MONTANA.

TUESDAY MORNING THROUGH WEDNESDAY MORNING... AS THE RIDGE AXIS
PASSES BY THE REGION... NATURAL INSTABILITY ON THE WESTERN SIDE
OF IT ALONG WITH SHORTWAVES AND NEW PACIFIC MOISTURE WILL SPARK
OFF OVER THE SURFACE TROUGH AND GENERATE SHOWERS AND THUNDERSTORMS
IN A NORTH/SOUTH ORIENTED LINE. THE LINE WILL REMAIN ORIENTED
NORTH/SOUTH ALONG THE RIDGE AXIS AS IT SLOWLY LUMBERS ACROSS THE
STATE. MODELS HAVE SHARPENED THE FOCUS AREA AND TIMING FOR THIS
LINE SO POPS ALONG NARROW CORRIDORS WERE RAISED WHILE OTHER AREAS
WERE LOWERED. CONFIDENCE HAS INCREASE MUCH FROM LAST NIGHT. WITH
LITTLE SHEAR AND A WEAK WINDOW FOR STRONG AFTERNOON CAPE THESE
STORMS LOOK MORE GENERAL THAN SEVERE WITH MAYBE HAIL BEING THE
BIGGEST THREAT.

WEDNESDAY... WITH BULK OF THE OVERNIGHT ACTIVITY EXITING THE STATE
EARLY IN THE MORNING... ATMOSPHERE WILL STABILIZE FOR ABOUT 12
HOURS BEFORE THE NEXT SHORTWAVES ARRIVAL OVER THE CENTRAL MONTANA
MOUNTAINS DURING THE AFTERNOON. THESE SHOWERS SHOULD HOLD OFF
UNTIL THE EVENING HOURS. GAH


.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
THE ONLY REAL CHANGE TO THE EXTENDED TO TO BRING IN SOME SCATTERED
POPS A LITTLE EARLIER SATURDAY EVENING. THE GFS...DGEX AND EC
ALL SHOW A LOW IN NE WYOMING WITH AN INVERTED TROF STRETCHING NW
TOWARDS THE CANADIAN ROCKIES. THE CMC IS THE ONLY ONE HOLDING BACK
A BIT WITH THAT SYSTEM KEEPING THINGS IN SW MT AND WY. FRANSEN

WEDNESDAY NIGHT AND THURSDAY... A COLD FRONT WILL MOVE THROUGH
EASTERN MONTANA WHICH WILL BE FOLLOWED BY AN UPPER TROUGH/LOW
THURSDAY AND THURSDAY NIGHT. THE FRONTAL PASSAGE WILL BRING
ENOUGH MOISTURE AND INSTABILITY FOR A GOOD CHANCE OF SHOWERS AND
THUNDERSTORMS. MODELS CURRENTLY TRACK THE UPPER LOW ACROSS
SOUTHERN SASKATCHEWAN WHICH WILL PUT MOST OF NE MONTANA IN A DRY
SLOT. THIS WILL LIMIT PRECIP CHANCES LATE THURSDAY NIGHT AND
FRIDAY. WILL MAINTAIN A SLIGHT CHANCE FOR NOW.

AN UPPER RIDGE ON SATURDAY WILL ALLOW FOR DRY WEATHER MOST OF THE
DAY. FLOW ALOFT TURNS SOUTHWEST BY EVENING AND COULD BRING A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS SOUTH OF THE MISSOURI
RIVER IN THE AFTERNOON AND EVENING WITH CHANCES FOR THUNDERSTORMS
OVERSPREADING THE ENTIRE FORECAST AREA LATE SATURDAY NIGHT AND
SUNDAY AS A FRONTAL SYSTEM AND SHORTWAVE TROUGH MOVES THROUGH THE
AREA. CHANCES FOR SHOWERS AND THUNDERSTORMS LINGER INTO SUNDAY
NIGHT BEFORE THE TROUGH MOVES TO THE EAST ON MONDAY WITH MAINLY
DRY WEATHER. FORRESTER


&&

.AVIATION...
FLIGHT CATEGORY: VFR OUTSIDE OF THUNDERSTORMS.

SYNOPSIS: UPPER RIDGING WILL MAKE FOR MOSTLY CLEAR SKIES AND
EXCELLENT FLYING WEATHER TONIGHT. SOME HAZE FROM WILDFIRES WILL
REMAIN IN THE REGION...BUT WILL NOT RESTRICT VSBY. STARTING MID
AFTERNOON ON TUESDAY THUNDERSTORMS WILL BEGIN TO APPROACH THE TAF
SITES FROM THE WEST. BRIEF PERIODS OF HEAVY RAIN...GUSTY ERRATIC
WINDS TO 40 MPH...AND SMALL HAIL WILL BE POSSIBLE WITH
THUNDERSTORMS.

CIGS: SKC-SCT200 THROUGH MIDDAY TUESDAY...THEN INCREASING MIDLEVEL
CUMULUS BUILDUPS.

VSBY: UNRESTRICTED.

WINDS: EAST TO SOUTHEAST 5-10KTS TONIGHT IN MOST AREAS. KGGW WILL
HAVE STRONGER EAST WINDS AROUND 15 KNOTS TONIGHT DUE TO THE LOCAL
EFFECTS OF THE MILK RIVER VALLEY. BY 18Z ON THE 4TH...ALL SITES
SHOULD HAVE A PRETTY STIFF EAST-SOUTHEAST WIND AT 14-17KTS. THE
PASSING SURFACE TROUGH WILL BRING A SWITCH TO WEST WINDS FROM WEST
TO EAST TUESDAY EVENING.

FRANSEN/GILCHRIST


&&

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

&&

$$

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.