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000
FXUS65 KGGW 132057
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
257 PM MDT MON MAY 13 2013

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH WEDNESDAY...
THE UPPER TROUGH REMAIN WELL OFF TO THE WEST...BUT THE EXIT REGION
HAS BEEN HIGHLIGHTED FOR SLIGHT CHANCE FOR SEVERE THUNDERSTORMS
BY SPC. THIS AREA EXTENDS WELL INTO THE WESTERN HALF OF THE CWA.
TODAY WAS WARM LIKE SUNDAY BUT THE DEW POINTS WERE A LITTLE
HIGHER...INCREASING THE LEVEL OF INSTABILITY. YET THE COLD FRONT
WILL BE POSITIONED ALONG THE FRONT RANGE AT 00Z THIS EVENING AND
SHOULD NOT REACH NORTHEAST MONTANA UNTIL MID EVENING...WHEN
INSTABILITY IS BEGINNING TO LOSE ITS STRENGTH AROUND SUNSET. THE
MAIN THREAT TO ANY THUNDERSTORM APPEARS TO THE POSSIBILITY OF
STRONG WINDS AS INDICATED BY THE INVERTED-V SOUNDING PROFILE AT
00Z. CONVECTIVE PARAMETERS SHOW MODERATE TO GOOD SUPPORT FOR A
GENERAL THUNDERSTORM THREAT ACROSS NORTHEAST MONTANA THIS EVENING
AND TONIGHT. OVERALL SEVERE THUNDERSTORM PARAMETERS DIMINISH
THROUGH NORTHEAST MONTANA THROUGH THE EVENING HOURS. A GOOD
WETTING RAIN CAN BE EXPECTED FOR MUCH OF OUR CWA. MODELS FAVOR
AREAS NORTH OF THE HI-LINE FOR THE BEST QPF...UP TO A QUARTER
INCH. LESSER AMOUNTS ARE EXPECTED SOUTH OF THE MISSOURI RIVER.

STRONG WIND TODAY WITH LOW RH HAS CREATED CRITICAL FIRE WX
CONDITIONS. THEREFORE ISSUED A RED FLAG WARNING THROUGH TUESDAY
EVENING. SEE FIRE WX DISCUSSION. IN ADDITION...WIND OVER FORT PECK
LAKE BECAME HAZARDOUS TO BOATERS WITH CONDITIONS CONTINUING THROUGH
TUESDAY WENT AHEAD AND ISSUED A LAKE WIND ADVISORY THROUGH TUESDAY
EVENING.

TUESDAY...THE VIGOROUS COLD FRONT PASSING THROUGH THE CWA LATE
TONIGHT AND EARLY TUESDAY MORNING WILL BRING STRONG SUBSIDENCE
AND COLD AIR ADVECTION BEHIND THE FRONT. THIS WILL ALLOW STRONG
AND ENHANCED WINDS BEHIND THE FRONT TO PERSIST THROUGHOUT MOST OF
THE DAY ON AS ISOLATED SHOWERS LINGER ALONG THE CANADIAN BORDER.
THE COOLER AIR WILL CAP MAXIMUM TEMPERATURES MUCH LOWER THAN
THOSE ON MONDAY...BUT WITH GOOD MIXING...HIGHS WILL CONTINUE ABOVE
AVERAGE. CRITICAL FIRE WEATHER CONDITIONS LOOK MORE LIKELY ON
TUESDAY WITH WIDESPREAD SUSTAINED WINDS IN EXCESS OF 25 TO 20
KNOTS. SEE FIRE WEATHER DISCUSSION.

TUESDAY NIGHT AND WEDNESDAY...WIND DIMINISHES RAPIDLY IN THE
EVENING AS THE SHORT WAVE MOVES INTO THE GREAT LAKES REGION.
ZONAL FLOW WILL SETTLE THINGS DOWN FOR A MILD DAY. THIS WILL ALLOW
TEMPERATURES TO CREEP UP SLIGHTLY OVER HIGHS ON TUESDAY AS A VERY
WEAK RIDGE COVERS THE REGION. SCT

.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
UPDATE...GOING FORECAST WAS IN OVERALL EXCELLENT SHAPE DEPICTING A
DRY ZONAL FLOW THROUGH MIDWEEK...FOLLOWED BY A COOLER MORE
UNSETTLED UPPER TROUGH FOR THURSDAY AND BEYOND. ONLY TWEAKS WERE
MAINLY MADE FOR CONSISTENCYS SAKE...NO SIGNIFICANT CHANGES WERE
MADE. GILCHRIST

PREVIOUS DISCUSSION...EXTENDED PERIOD OPENS WITH DRY ZONAL FLOW
OVER MONTANA. BY THURSDAY MORNING FLOW BEGINS TO TURN INCREASINGLY
SOUTHWEST WITH UPPER TROF PUSHING ACROSS THE WEST COAST AND INTO
THE GREAT BASIN. MODELS IN GOOD AGREEMENT WITH SLOWLY LIFTING THIS
TROF INTO THE NORTHERN PLAINS OVER THE WEEKEND THEN FORMING A
CLOSED LOW IN THE UPPER MIDWEST EARLY NEXT WEEK. SOME INDICATION
OF THE FIRST GOOD LOW LEVEL JET FROM THE GULF INTO THE NORTHERN
PLAINS DEVELOPING ON THURSDAY. THIS WILL INCREASE THE MOISTURE
AVAILABLE FOR THE INCOMING SYSTEM...WHICH ALREADY WILL CONTAIN MID
TO HIGH LEVEL PACIFIC MOISTURE...LEADING TO THE POTENTIAL FOR
SIGNIFICANT RAINFALL FOR MUCH OF THE REGION SOMETIME OVER THE
WEEKEND. EBERT

&&

.AVIATION...
VFR. TODAY WILL BRING SCT-BKN HIGH CLOUDS ALONG WITH WESTERLY
WINDS AT 20 TO 30KTS.

AN APPROACHING COLD FRONT TONIGHT COULD CAUSE A FEW STRONG TO
SEVERE THUNDERSTORMS DURING THE LATE AFTERNOON AND EVENING WITH
GUSTY WINDS AND BRIEF MVFR FLIGHT CONDITIONS.

WINDS ARE EXPECTED TO INCREASE SIGNIFICANTLY BEHIND THE FRONTAL
PASSAGE EARLY TUESDAY MORNING...LASTING THROUGH THE DAY ON
TUESDAY. GILCHRIST

&&

.FIRE WEATHER...

A FRONT MOVING THROUGH EASTERN MONTANA HAS BROUGHT STRONG WINDS OF
15 TO 25 MPH WITH GUSTS TO 35 MPH OVER MOST OF THE AREA. WITH LOW
RELATIVE HUMIDITY...CRITICAL FIRE WEATHER CONDITIONS HAS BEEN
REACHED. THEREFORE ISSUED A RED FLAG WARNING FOR MOST OF NORTHEAST
MONTANA...EXCEPT ZONE 137 WHERE WIND IS MUCH LESS.

A MORE VIGOROUS COLD FRONT WILL SLIDE THROUGH THE REGION LATE
TONIGHT. STRONG SUBSIDENCE AND COLD AIR ADVECTION WILL SUSTAIN
STRONG AND GUSTY WIND FROM THE WEST THROUGH THE ENTIRE DAY
TUESDAY. ALTHOUGH COOLING TEMPERATURES WILL RESULT IN HIGHER
HUMIDITY...THE MUCH STRONGER WINDS WILL MAINTAIN CRITICAL FIRE
CONDITIONS THROUGH TUESDAY EVENING. THEREFORE WITH AN EARLY START
TO THE STRONG WINDS THE RED FLAG WARNING WILL CONTINUE THROUGH
EARLY EVENING WITH THE ADDITION OF FIRE ZONE 137.

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM 6 AM TO 9 PM MDT TUESDAY FOR MTZ137.

RED FLAG WARNING UNTIL 9 PM MDT TUESDAY FOR MTZ120-122-134>136.

LAKE WIND ADVISORY UNTIL 9 PM MDT TUESDAY FOR FOR FORT PECK
LAKEFORT PECK LAKE.

&&

$$

WEATHER.GOV/GLASGOW