Hail in Montana, May 1, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
301 PM MDT TUE MAY 1 2007

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY...
UPPER TROF PUSHING INTO THE PACIFIC NORTHWEST WILL BE THE MAIN
WEATHER MAKER FOR NORTHEAST MONTANA THROUGH THE SHORT TERM. RIDGE
OVER THE REGION TODAY WILL BE SLOWLY PUSHED TO THE EAST. THIS WILL
OPEN EASTERN MONTANA TO SOUTHWEST FLOW AND INCREASE MOISTURE AND
ENERGY EJECTING FROM THE TROF. SURFACE BOUNDARY EXPECTED TO SET UP
IN CENTRAL MONTANA AND SLIDE VERY SLOWLY EAST THROUGH THURSDAY.
STRONG LOW LEVEL SOUTHEAST JET AHEAD OF THE FRONT WILL KEEP WINDS
STRONG ACROSS THE REGION AND WILL KEEP THE LAKE WIND ADVISORY.
BEST MOISTURE AND LIFT WILL BE ALONG AND WEST OF THE FRONT...
MOVING ACROSS EASTERN MONTANA WEDNESDAY NIGHT AND THURSDAY. STRONG
WARM AIR ADVECTION ALSO AHEAD OF THE FRONT TO PUSH TEMPERATURES
TOWARD 80 ON WEDNESDAY AND ONLY A FEW DEGREES COOLER ON THURSDAY
DUE TO INCREASE IN CLOUD COVER. EBERT

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...
NO CHANGES OF SIGNIFICANCE TO PREVIOUS LONG TERM PACKAGE. LATEST
ECMWF AND GFS CONTINUE TO CONVERGE ON A SOLUTION REGARDING THE
DEVELOPMENT AND BEHAVIOR OF THE CUT OFF LOW FORECAST TO SINK INTO
THE FOUR CORNERS REGION THIS WEEKEND. GFS CONTINUES TO BE THE MORE
AGGRESSIVE OF THE TWO WITH THE NORTHERN STREAM TROUGHING ACROSS
THE LOCAL AREA BY LATE SATURDAY WHILE THE ECMWF MAINTAINS A
STRONGER RIDGE EXTENSION OVERHEAD COURTESY OF THE OMEGA BLOCK
DOWNSTREAM. NOT ENOUGH EVIDENCE EITHER WAY TO JUSTIFY TWEAKING POP
GRIDS ANY...SO WILL CONTINUE TO MONITOR FUTURE MODEL RUN TRENDS. MCZ

PREVIOUS LONG TERM DISCUSSION...
AN UPPER TROUGH WHICH IS CURRENTLY IN THE GULF OF ALASKA WILL BE
THE MAIN WEATHER FEATURE DURING THE EXTENDED PERIOD. THE WEATHER
PATTERN WILL BECOME HIGHLY AMPLIFIED LATE THIS WEEK INTO THE
WEEKEND.

THURS NIGHT & FRIDAY...AN UPPER TROUGH NOW IN THE PACIFIC REALLY
DIGS INTO THE WESTERN UNITED STATES LATE THIS WEEK WHILE TAKING ON
A NEGATIVE TILT.   THE LOCAL AREA WILL BE A STRONG SOUTHERLY FLOW
AHEAD OF THE STRONG UPPER LOW.  THIS SHOULD KEEP THE AREA UNSETTLED
WITH SOME SHOWER AND THUNDERSTORM ACTIVITY.  IT IS REALLY IMPOSSIBLE
THIS FAR OUT TO KEY IN ON ANY PARTICULAR SHORTWAVE IN THE FLOW THAT
COULD ENHANCE THE CHANCE OF PRECIPITATION.  THE ONGOING FORECAST
THAT HAS A CHANCE OF SHOWERS THURSDAY NIGHT AND A CHANCE OF SHOWERS
AND THUNDERSTORMS ON FRIDAY SEEMS REASONABLE.  AS THE TIME PERIOD
NEARS HOPEFULLY WE WILL BE ABLE TO REFINE THE POPS A BIT AND GIVE A
BETTER INDICATION OF JUST WHEN AND WHERE THE HIGHEST CHANCES WILL
RAIN WILL BE FOUND.

NEXT WEEKEND...DECENT AGREEMENT BETWEEN THE VARIOUS MODELS THAT
THE WESTERN LOW FORMS INTO A STRONG CUT OFF LOW ACROSS THE
SOUTHWEST. FROM A CLIMATOLOGY STANDPOINT THIS IS A HIGHLY FAVORED
SOLUTION. THIS WOULD SET UP AN OMEGA BLOCK WITH STRONG RIDGING TO
OUR EAST AND ANOTHER UPPER LOW IN THE ATLANTIC. THIS COULD VERY
WELL LEAD TO A DRY...OR AT LEAST MOSTLY DRY WEEKEND AS THE AREA
REMAINS CUT OFF FROM THE DEEPER MOISTURE WELL TO OUR SOUTHWEST.
STILL A FAIR AMOUNT OF UNCERTAINTY NORTH OF THE CLOSED LOW AS FAR
AS THE UPPER AIR PATTERN ACROSS NORTHEAST MONTANA. SOME MODELS AND
ENSEMBLES HAVE SOME TROUGHINESS IN THE NORTHERN BRANCH THAT
EXTENDS INTO THE AREA.  OTHERS HAVE THE AREA UNDER SOME WEAK
RIDGING THAT EXTENDS NORTHEAST OF THE CUT OFF LOW. TEND TO FAVOR
THE LATER SOLUTION WHICH WOULD KEEP THE AREA CUT OFF FROM THE
MOISTURE TO THE SOUTH.  UNTIL THERE IS BETTER CONSISTENCY WILL NOT
MAKE ANY SIGNIFICANT CHANGES TO THE ONGOING FORECAST. LOWERED THE
CLOUD COVER SOME FOR SUNDAY IN THE NORTH...AND LATER SHIFTS MAY
NEED TO CONSIDER LOWER POPS/CLOUD COVER AND RAISING TEMPS FOR
SUNDAY.

MONDAY & TUESDAY...A LOT OF UNCERTAINTY.  KIND OF LIKE THE NOGAPS
SOLUTION THAT KEEPS THE LOW IN THE SOUTHWEST AND THE LOCAL AREA HIGH
AND DRY WELL TO THE NORTH.  ESPECIALLY WITH A STRONG RIDGE TO OUR
EAST AND A TROUGH OFF THE EAST COAST IT WOULD FAVOR KEEPING THINGS
SLOW MOVING.  JUST ABOUT ANYTHING COULD HAPPEN WITH THE LOW IN THE
SOUTHWEST FROM HAVING IT PUSHED OUT INTO THE PACIFIC TO IT LIFTING
NORTHEAST.  IT LOOKS LIKE THE ONLY REAL THREAT OF SHOWERS WILL BE IF
IT WERE TO EJECT NORTHEAST TOWARD THE AREA AND BEGIN TO OPEN UP
SOME.  FOR NOW WILL KEEP SOME VERY LOW POPS IN FOR EARLY NEXT
WEEK...BUT BELOW THE THRESHOLD FOR A MENTION OF PRECIPITATION IN THE
FORECAST. CB

&&

.AVIATION...
VFR. SCATTERED LOW TO MID LEVEL CLOUDS CURRENTLY ACROSS THE FAR
EASTERN AREAS WILL EXIT EARLY THIS EVENING. SOUTHEASTERLY WINDS
WILL REMAIN BREEZY AT GGW THROUGH THE OVERNIGHT INTO WEDNESDAY
WITH GUSTS TO 35 KTS POSSIBLE BY WEDNESDAY AFTERNOON. REMAINING
TAF SITES CAN EXPECT TO SEE WINDS DIMINISH THIS EVENING BEFORE
INCREASING WEDNESDAY MORNING. MCZ

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 7 PM MDT THURSDAY FOR FORT PECK LAKE.

&&

WEATHER.GOV/GLASGOW