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000
FXUS65 KGGW 200153
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
753 PM MDT WED JUN 19 2013

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH FRIDAY...
UPDATE...CENTRAL MONTANA CONVECTION CONTINUES TO MOVE NORTH...SOME
CELLS HAVE STARTED IN PETROLEUM COUNTY THIS EVENING. WATER VAPOR
IS SHOWING DIFULENT FLOW ALOFT WITH A WAVE MOVING INTO THE REGION
FROM THE SOUTH. THE HRRR IS DOING OK TONIGHT AND SUPPORTS CURRENT
THINKING AND NATIONAL CENTER THINKING THAT A COMPLEX OF
THUNDERSTORMS IS MOST LIKELY FOR NORTHEAST MONTANA FOR THE LATE
EVENING HOURS INTO THE EARLY OVERNIGHT HOURS. THE LEADING EDGE OF
THIS COULD PRODUCE VERY GUSTY WINDS...AND THEN RAIN HEAVY AT
TIMES. THIS CONTINUES TO SUPPORT THE PHILLIPS COUNTY FLASH FLOOD
WATCH AND ZONE WORDING. DID TWEAK ELEMENTS AROUND TO BEST FIT THE
CURRENT SITUATION.     PROTON

A CLOSED UPPER LEVEL LOW CONTINUES TO SPIN ACROSS THE PACIFIC
NORTHWEST. SHORTWAVE ENERGY PIVOTING AROUND THIS CLOSED LOW IS
PROPAGATING THROUGH SOUTHWEST FLOW ALOFT AND WILL BE RESPONSIBLE
FOR THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS THIS EVENING.
PLENTY OF CAPE EXISTS BUT WIND SHEAR PROFILES ARE NOT ALL THAT
IMPRESSIVE. THERE IS GOOD DIRECTIONAL SHEAR BUT SPEED SHEAR IS
LACKING. GIVEN CAPE/SHEAR PROFILES...WILL EXPECT DEVELOPING
SUPERCELLS TO FORM INTO LINE SEGMENTS THIS EVENING AS THEY PUSH
FROM THE SOUTHWESTERN ZONES THIS EVENING NORTHEASTWARD THROUGH THE
OVERNIGHT. TEMPERATURES THIS AFTERNOON HAVE BEEN WELL INTO THE
80S...SURFACE DEW POINTS HAVE BEEN HOVERING AROUND 60
DEGREES...AND SO THERE IS PLENTY OF WARM...MOIST...LOW LEVEL AIR.
STEEP MIDLEVEL LAPSE RATES ARE ALSO EVIDENT IN NAM BUFKIT
SOUNDINGS.

CONSIDERING ALL OF THIS...A FEW STORMS MAY BECOME SEVERE WITH
LARGE HAIL AND DAMAGING WINDS. HOWEVER...THE PRIMARY THREAT AT
THIS POINT WILL BE THE HEAVY RAINFALL. NAM BUFKIT SOUNDINGS SHOW
PRECIPITABLE WATER VALUES BETWEEN AN INCH AND AN INCH AND A HALF.
THE LATEST NAM/GFS/ECMWF SHOWS THE POTENTIAL FOR HEAVY RAINFALL
ACROSS THE CWA...WITH THE BEST AGREEMENT IN PHILLIPS AND NORTHERN
VALLEY COUNTIES. THIS IS FURTHER SUPPORTED BY THE SREF. THE HRRR
MODEL HAS ALSO BEEN INSISTING ON DEVELOPING CONVECTION AROUND 00Z
IN THE SOUTHWEST AND HAVING IT FORM INTO A LINE AS IT PUSHES
NORTHEAST OVERNIGHT. THEREFORE...SOME OF THE FAR NORTHEASTERN
ZONES MAY ACTUALLY STAY DRY UNTIL MORNING. GIVEN POTENTIAL FOR
EXCESSIVE RAINFALL RATES TO OCCUR OVER A SHORT DURATION...WILL
HOIST A FLASH FLOOD WATCH FOR PHILLIPS COUNTY. WILL OPT TO LEAVE
OUT NORTHERN VALLEY AT THIS POINT BECAUSE BEST AGREEMENT IS ON
RAINFALL FURTHER WEST BUT THE NEXT SHIFT WILL HAVE TO MONITOR
CLOSELY. A LAKE WIND ADVISORY REMAINS IN EFFECT UNTIL MIDNIGHT AND
GIVEN WINDS ALONG FORT PECK LAKE RECENTLY GUSTING ABOVE 40
MPH...THIS HEADLINE LOOKS GOOD.

SHOWERS AND THUNDERSTORMS MAY LINGER IN THE NORTHEASTERN ZONES ON
THURSDAY. OTHERWISE BEHIND THE COLD FRONTAL PASSAGE EXPECT MUCH
COOLER TEMPERATURES FOR AFTERNOON HIGHS. THE UPPER LOW ACROSS THE
PACIFIC NORTHWEST WILL REMAIN FIRMLY IN PLACE THROUGH FRIDAY
THOUGH AS ADDITIONAL SHORTWAVE ENERGY PUSHES INTO THE FORECAST
REGION. THUS...AFTER A BREAK IN BETWEEN SYSTEMS ON THURSDAY
NIGHT...INCREASED POPS AGAIN ON FRIDAY WITH THE NEXT APPROACHING
SHORTWAVE FEATURE. MALIAWCO

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
GOING FORECAST IN GOOD SHAPE BUT DID TWEAK UP THE POPS/WEATHER FOR
LATE SATURDAY INTO EARLY SUNDAY AS SHOWERS SEEM TO BE A PRETTY GOOD
BET WITH THE UPPER LOW IN PROXIMITY. JAMBA

PREVIOUS DISCUSSION...
LONG TERM FORECAST PERIOD BEGINS AS THE MAIN ENERGY FROM THE
MEANDERING LOW PRESSURE SYSTEM OVER THE PACIFIC NORTHWEST AND
NORTHERN ROCKIES REGIONS FINALLY KICKS OUT THROUGH THE EASTERN
SLOPES OF THE ROCKY MOUNTAINS AND THEN THE NORTHERN HIGH PLAINS
THROUGH THE REMAINDER OF THE WEEKEND.

EXPECT THIS WEEKEND TO BE FAIRLY WET WITH A LITTLE UNCERTAINTY
REGARDING PRECIPITATION AMOUNTS AS THE 00Z RUN OF THE EC HAS YET
TO COME IN. SOME COMPARISONS SHOW SIGNIFICANT DISCREPANCIES TO THE
POINT OF BEING EXACT OPPOSITES. WOULD HAVE TO GIVE IT LESS THAN
AVERAGE FORECAST CONFIDENCE AT BEST. TRIED TO INCREASE POPS IN A
BROAD-BRUSHED AND BLENDED KIND OF WAY WHERE BEST MODEL AGREEMENT
IF ANY WAS TO BE FOUND...THEN REDUCED POPS SIMILARLY WHERE MODELS
AGREED IN THE LACK THEREOF.

THERE SEEMS TO BE A BRIEF SHORT WAVE RIDGE FROM SUNDAY THROUGH
MONDAY MORNING WHICH SHOULD BRING AN END TO THE WET PERIOD FROM
THE WEEKEND.

NORTHEAST MONTANA THEN FINDS ITSELF IN A PERSISTENT ZONAL OR
SLIGHTLY SOUTHWESTERN FLOW ALOFT WITH SOME SMALL SCALE EMBEDDED
DISTURBANCES. ALTHOUGH THE MODELS ARE TRENDING A BIT DRIER TOWARD
THE END OF THE FORECAST PERIOD AS THE GULF OF ALASKA LOW BATTLES
AGAINST THE FOUR CORNERS HIGH. BMICKELSON

&&

.AVIATION...
VFR CONDITIONS ARE EXPECTED BUT MVFR CONDITIONS ARE POSSIBLE
STARTING AT GLASGOW THIS EVENING. EVENING SHOWERS AND
THUNDERSTORMS WILL CONTINUE OVERNIGHT...MOST OF THEM ARE EXPECTED
TO IMPACT LOCATIONS ALONG AND NORTH OF HIGHWAY 2 WITH HEAVY RAIN
POSSIBILITIES.

SOUTHEAST WINDS WILL DECREASE TONIGHT AS A COLD FRONT ARRIVES FROM
THE WEST/SOUTHWEST. EXPECT WEST WINDS ON THURSDAY AT ABOUT 10 TO
20 KTS. JAMBA

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 6 AM MDT THURSDAY FOR CENTRAL AND
SOUTHEAST PHILLIPS...NORTHERN PHILLIPS...SOUTHWEST PHILLIPS.

LAKE WIND ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR FORT PECK LAKE
FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.

&&

$$

WEATHER.GOV/GLASGOW