Wildfire in Montana, September 16, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
230 PM MDT SUN SEP 16 2007

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH TUESDAY...
A COLD FRONT WILL CROSS THE AREA TOMORROW RETURNING TEMPERATURES TO
MORE SEASONABLE LEVELS BY TUESDAY.  THE BEST CHANCE OF SHOWERS IN
THE SHORT TERM WILL BE MONDAY NIGHT SOUTH OF THE MISSOURI RIVER.

TONIGHT...UPPER TROUGHS ARE VISIBLE ON SATELLITE ACROSS THE SOUTHERN
YUKON/NORTHERN BC AND ACROSS THE INTERMOUNTAIN WEST.  THESE TROUGHS
WILL JOIN FORCES TO CARVE OUT A FULL LATITUDE TROUGH FROM NORTHERN
ALBERTA SOUTH INTO THE SOUTHWEST UNITED STATES.  THIS WILL PUT THE
LOCAL AREA IN A SOUTHWEST FLOW ALOFT.  ANY SIGNIFICANT MOISTURE
SHOULD REMAIN ALONG AND WEST OF THE DIVIDE TONIGHT WITH NOTHING MORE
THAN SOME HIGH CLOUDS ACROSS THE LOCAL AREA.  AREA RADARS SHOWING
SOME ISOLATED CONVECTION ACROSS WESTERN AND CENTRAL MONTANA...AND
EXPECT MOST OF THIS TO TAKE A BIG HIT WITH THE LOSS OF DAYTIME
HEATING.  DEW POINT DEPRESSIONS ARE ALSO ON THE ORDER OF 50+ DEGREES
(F) ACROSS THE WESTERN ZONES SO ANYTHING THAT DOES DRIFT IN FROM THE
SOUTHWEST EARLY THIS EVENING IS NOT LIKELY TO BE MORE THAN A LITTLE
VIRGA WITH PERHAPS A BRIEF GUST OF WIND. THE AIRMASS HAS
CONTINUED TO WARM DURING THE LAST 48 HOURS AND TEMPERATURES
TONIGHT WILL NOT BE AS COOL AS THE LAST FEW NIGHTS. WITH THE
EXCEPTION OF SOME OF THE DEEPER RIVER VALLEY BOTTOMS WHICH MAY
DROP INTO THE 40S THE REST OF THE CWA SHOULD HAVE LOWS IN THE 50S.

MONDAY...THE UPPER TROUGH AXIS BEGINS TO PUSH EAST AND OUT INTO
CENTRAL MONTANA BY LATE IN THE DAY.  A WEAK COLD FRONT WILL SLIDE
EAST OF THE AREA DURING THE AFTERNOON WITH SOME COLD AIR ADVECTION
IN IT/S WAKE.  THE UPPER ENERGY ALSO BEGINS TO SPLIT WITH THE BEST
MOISTURE REMAINING TO THE NORTH AND SOUTHWEST OF THE AREA.  IT WILL
ALSO TAKE SOME TIME FOR THE LOW/MID LEVELS TO MOISTEN UP WHICH
SHOULD MAKE FOR A DRY DAY.  TEMPERATURES WILL NOT BE AS WARM AS
TODAY...BUT WITH A MILD START TO THE DAY TEMPERATURES WILL STILL END
UP SEVERAL DEGREES ABOVE AVERAGE.

MON NIGHT & TUESDAY...THE UPPER TROUGH CONTINUES TO SLIDE EAST
MONDAY NIGHT WITH THE ENERGY SPLITTING WITH THE SOUTHERN BRANCH
TROUGH PUSHING THROUGH WYOMING.  THIS MAY PRODUCE A FEW SHOWERS
MONDAY NIGHT...MAINLY SOUTH OF THE MISSOURI.  BY TUESDAY...THE
SHORTWAVE TROUGH PUSHES WELL EAST OF THE AREA WITH SOME WEAK MID
LEVEL RIDGING BETWEEN THE DEPARTING TROUGH AND AN UPPER TROUGH THAT
WILL BEGIN TO RE-LOAD IN THE PAC NW.  THIS WILL ALLOW SOME DRIER AIR
TO TEMPORARILY FILTER INTO THE AREA.  THE BIGGEST CHANGE DURING THIS
TIME WAS TO DRY OUT THINGS FROM WEST TO EAST ON TUESDAY.  HEIGHTS
AND THICKNESS VALUES AS WELL AS 850MB TEMPS SUPPORT TEMPERATURES
NEAR TO SLIGHTLY BELOW AVERAGE. CB

.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
THERE IS BETTER CONSISTENCY IN THE FORECAST MODELS THROUGH
THURSDAY...THUS HIGHER CONFIDENCE. MODELS ARE CONSISTENT WITH A
CUT OFF LOW FORMING OVER THE WEST COAST TUESDAY NIGHT...DROPPING
SOUTHWARD INTO CALIFORNIA ON WEDNESDAY. EASTERN MONTANA WOULD SEE
A SOUTHWEST FLOW ALOFT UNDER THIS PATTERN WITH EMBEDDED SHORTWAVE
ENERGY SPUN OFF THE DIVING LOW...MAKING FOR A CHANCE OF SHOWERS.

AS THE LOW BECOMES FREE OF THE GENERAL FLOW PATTERN ON THURSDAY...A
SECOND TROUGH WILL DROP SOUTHWARD OUT OF CANADA...BRINGING WITH IT
COOLER TEMPERATURES AND CONTINUED CHANCES FOR SHOWERS.

THURSDAY NIGHT AND BEYOND CONFIDENCE FALLS OFF CONSIDERABLY
GIVEN THE UNCERTAINTY IN THE FORECAST MODELS WITH HOW TO HANDLE
THE CLOSED LOW OVER CALIFORNIA. WOULD EXPECT THE LOW TO BECOME
CAUGHT UP IN THE FLOW BEHIND THE EXITING TROUGH...POSSIBLY
EJECTING ACROSS EASTERN MONTANA LATE IN THE PERIOD WHEN ALL IS
SAID AND DONE. BUT GIVEN THE LACK OF CONFIDENCE PREFERRED THE
CONSISTENCY OF THE GOING FORECAST. GILCHRIST

PREVIOUS LONG TERM DISCUSSION...PERIOD CONTINUES TO LOOK
UNSETTLED...BUT MODELS SHOWED BETTER AGREEMENT TONIGHT. LOOKS LIKE
WED-THU TO BE THE BEST SHOT FOR PRECIP WITH THE POSSIBILITY
RETURNING NEXT WEEKEND.

PERIOD STARTS OFF WITH A WEST COAST TROUGH DIGGING AND CUTTING OFF
BY WEDNESDAY AS IT LOOKS TO BECOME AN INSIDE SLIDER DROPPING INTO
CENT/S CA BY FRIDAY. THEN MOST OF THE MODELS EJECT IT NORTHEAST OVER
THE WEEKEND INTO MONTANA THANKS TO A KICKER COMING INTO THE PACIFIC
NORTHWEST.

TUESDAY NIGHT THRU THURSDAY...SW FLOW ALOFT OVER THE AREA IS
PREVALENT WITH THE NORTHERN BRANCH OF THE TROUGH MOVING THROUGH THE
AREA ABOUT THURSDAY. THE OPERATIONAL GFS WAS A BIT SHARPER THAN ITS
ENSEMBLE MEMBERS AND COMPARED TO OTHER MODELS. BUT ALL WERE IN
AGREEMENT WITH MOISTURE AFFECTING THE REGION. THEREFORE POPS
OVERSPREADING THE AREA STILL LOOK GOOD. SOME OF THE MODELS ARE
SHOWING SIGNS THAT MOST OF THE PRECIP WILL COME WED NT...SO
INCREASED POPS FURTHER.

SYSTEM LOOKS TO BEGIN LIFTING OUT THURSDAY OR THURSDAY NIGHT...SO
POPS WERE DECREASED FROM WEST TO EAST INTO THUR NT. BY FRIDAY...THE
OPERATIONAL GFS AN OUTLIER WITH THE NORTHERN JET STREAM AS IT BRINGS
IT STRETCHES FROM THE PAC NW TO THE NORTHERN PLAINS. IT/S ENSEMBLE
AND OTHER MODELS KEEP THE JET NORTH OF THE CANADIAN BORDER.
THEREFORE LOWERED POPS FOR FRIDAY AND FRIDAY NIGHT TO WHERE VERY
LITTLE WEATHER IS MENTIONED. THEN CUT-OFF LOW BEGINS TO MOVE TOWARD
MONTANA FRIDAY NIGHT/SATURDAY. THIS SYSTEM LOOKS LIKE IT WILL BRING
SHOWERS TO THE AREA...BUT EXACTLY WHEN IS STILL UP IN THE AIR AT
THIS POINT. FOR NOW BROADBRUSHED WITH SLIGHTLY ABOVE CLIMATOLOGY
POPS.

TEMPERATURES THROUGH THE PERIOD TAKE A SLIGHT ROLLER COAST RIDE WITH
READINGS CLOSE OR SLIGHTLY BELOW NORMAL INTO FRIDAY. THEY THEN LOOK
TO RIDE ABOVE NORMAL SATURDAY AHEAD OF THE EXPECTED SYSTEM THEN COOL
OFF FOR SUNDAY. JAMBA

&&

.AVIATION...
FOR THE MOST PART VFR. MAINLY CLEAR SKIES AND LIGHT WINDS ARE
EXPECTED THROUGH THE REMAINDER OF THE WEEKEND. HOWEVER ISOLATED
THUNDERSTORMS WILL CONTINUE TO FORM ACROSS THE MOUNTAINS OF
CENTRAL MONTANA...DRIFTING EASTWARD ONTO THE PLAINS THROUGH THE
EVENING. WIND GUSTS TO 40 MPH ARE THE MAIN THREAT FROM STORMS THIS
EVENING. GILCHRIST

&&

.FIRE WEATHER...
A COLD FRONT WILL CROSS THE DISTRICTS TOMORROW.  IN THE WAKE OF THIS
FRONT THE WIND WILL PICK UP OUT OF THE NORTHWEST TO AROUND 15 MPH
DURING THE AFTERNOON...WITH A FEW GUSTS TO AROUND 25 MPH POSSIBLE.
TEMPERATURES WILL BE A FEW TO SEVERAL DEGREES COOLER
TOMORROW...WHICH SHOULD KEEP MINIMUM RELATIVE HUMIDITIES A BIT
HIGHER THAN TODAY.  CONDITIONS MAY COME CLOSE TO CRITICAL LEVELS FOR
A FEW HOURS IN DISTRICT 122 TOMORROW AFTERNOON.  A FEW SHOWERS ARE
POSSIBLE ACROSS THE SOUTHERN DISTRICTS MONDAY NIGHT.  TEMPERATURES
ON TUESDAY WILL BE MORE SEASONABLE ALONG WITH HIGHER AFTERNOON
RELATIVE HUMIDITIES.  CB

&&

.CLIMATE...
THE FIRST HALF OF SEPTEMBER TURNED OUT TO BE CLOSE TO NORMAL ON
TEMPERATURES AND RAINFALL. ALTHOUGH THE FIRST 4 DAYS WERE
HOT...THE 5TH THROUGH THE 15TH AVERAGED A LITTLE ON THE COOL
SIDE. THE AVERAGE TEMPERATURE THROUGH THE 15TH WAS 61.9
DEGREES...WHICH IS 1.4 DEGREES ABOVE NORMAL. RAINFALL OF 0.62
INCHES IS .09 INCHES ABOVE NORMAL. NEARLY ALL OF THAT OCCURRED ON
THE 7TH AND 8TH...THE MOST 24 HOUR RAINFALL IN NEARLY 3 MONTHS...
SINCE THE BIG JUNE 16TH STORM. THE FIRST FREEZE OCCURRED THE
MORNING OF THE 14TH...EARLIEST FREEZE IN GLASGOW SINCE 1993.
SIMONSEN

&&

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

&&

WEATHER.GOV/GLASGOW