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000
FXUS65 KGGW 170442
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
1042 PM MDT THU MAY 16 2013

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SATURDAY...
UPDATE INCLUDED LOWERING POPS AS CONVECTIVE SHOWERS WERE DIMINISHING
WITH THE LOSS OF DAYTIME HEATING. KEPT LIKELY POPS GOING FOR SHOWER
AREA NORTH OF WOLF POINT INTO DANIELS COUNTY AND GARFIELD COUNTY.
POPS WERE NOT LOWERED BELOW 30 PERCENT MOST AREAS WITH THE MOIST SW
FLOW IN PLACE.

LOW LEVEL MOISTURE WAS ON THE INCREASE OVER THE SE ZONES AS HIGHER
HUMIDITIES WERE ADVECTING IN ON AN EASTERLY FLOW. LOW CLOUDS ARE
CERTAIN AND FOG SEEMS TO BE A BETTER POSSIBILITY FOR THE HIGHER
ELEVATIONS INTO FRIDAY MORNING.  JAMBA

PREVIOUS SHORT TERM DISCUSSION...
SYNOPTICALLY UPPER LEVEL SOUTHWEST FLOW ALOFT WITH PERIODIC
EMBEDDED DISTURBANCES WILL DOMINATE THE WEATHER PATTERN INTO THE
WEEKEND. LOW LEVEL SOUTHEAST FLOW WILL PROVIDE AMPLE MOISTURE
SOURCED OUT OF THE GULF OF MEXICO...THUS EXPECT A CONTINUED TREND
TOWARD WETTER CONDITIONS IN THE SHORT TERM.

CURRENTLY SHOWERS CONTINUE TO SLOWLY BUILD IN FROM THE
SOUTHWEST...WITH WEAK CONVECTION SHOWING UP ALONG A LINE THAT
EXTENDS FROM MEDICINE LAKE TO VIDA. EXPECT THESE TRENDS TO
CONTINUE INTO THE EVENING HOURS...WITH ADDITIONAL SHOWERS AND
THUNDERSTORMS DEVELOPING ACROSS THE EAST AND SOUTHEAST.

OVERNIGHT TONIGHT INTO FRIDAY MORNING SHOWER ACTIVITY WILL CONTINUE AS
DISTURBANCES CROSS IN THE SOUTHWEST FLOW ALOFT. TEMPERATURES
OVERNIGHT WILL REMAIN ON THE WARM SIDE THANKS TO AMPLE CLOUD
COVER. SOUTHEAST WINDS WILL CONTINUE AT 8-12 MPH.

FRIDAY AFTERNOON CONVECTION ACROSS THE SOUTHEAST DOES NOT LOOK AS
STRONG AS IT DID IN PREVIOUS RUNS...WITH THE BEST POTENTIAL FOR
STRONG OR EVEN SEVERE STORMS WELL SOUTHEAST OF THE AREA. THUS
PULLED MENTION OF SMALL HAIL AND GUSTY WINDS FROM THE FORECAST.
WITH THAT SAID EXPECT WIDESPREAD SHOWERS WITH SCATTERED
THUNDERSTORMS DURING THE AFTERNOON AND EVENING HOURS.

AT THIS TIME THE WETTEST PERIOD OF THE SHORT TERM LOOKS TO BE ON
SATURDAY. SOME DIFFERENCES REMAIN ON EXACT PLACEMENT OF THE
HEAVIEST PRECIPITATION...AS THE MODELS DIFFER ON THE TRACK AND
POSITION OF THE ASSOCIATED 700 MB LOW. CURRENTLY PREFER THE ECMWF
SOLUTION WHICH IS FURTHER SOUTH AND MORE IN LINE WITH THE SREF
SOLUTION SO WENT AHEAD AND TRENDED UP POPS ACROSS THE SOUTHERN
ZONES. SHEAR AND INSTABILITY LOOK GOOD ENOUGH TO WARRANT A MENTION
OF SMALL HAIL AND GUSTY WINDS ACROSS THE SOUTHEAST DURING THE
AFTERNOON HOURS ON SATURDAY. GILCHRIST

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...

THE LONG TERM FORECAST BEGINS WITH A LARGE DEVELOPING SURFACE LOW
SUNDAY EAST AND SOUTHEAST OF MONTANA. THIS LOW IS THE MAJOR
WEATHER MAKER FOR SUNDAY THROUGH WEDNESDAY. LOW GRADUALLY MOVES
NORTH AND EAST WITH THE REGION NOT BEING OUT OF ITS AFFECTS UNTIL
LATE WEDNESDAY. SYSTEM GRADUALLY PHASES WITH AN UPPER STORM
SYSTEM...BECOMING VERTICALLY STACKED BY TUESDAY MORNING.

UPPER DYNAMICS ARE NOT PARTICULARLY STRONG WITH THIS SYSTEM...BUT
LOW WILL BRING CONSIDERABLE MOISTURE INTO THE AREA AND AN EXTENDED
PERIOD OF RAIN...SOME WIND...COOLER TEMPERATURES...AND SOME THUNDERSTORMS.
BEST PERIOD OF MOISTURE ADVECTION IN THE LONG RANGE FORECAST LOOKS
TO BE MONDAY WITH SURFACE FLOW BECOMING A LITTLE DRYER AND MORE
NORTHERLY AFTER THAT. AFTER SYSTEM EXITS...THE NEXT UPSTREAM
STREAM SYSTEM WILL BEGIN TO AFFECT THE AREA...KEEPING POPS
SOMEWHAT ELEVATED THROUGHOUT THE FORECAST.

DETAILS OF THE SURFACE LOW ARE SOMEWHAT UNRELIABLY REPRESENTED
IN THE MODELS. MOST MODEL RUNS HAVE A PERIOD OF WET WEATHER...BUT
THERE IS A LOT OF VARIANCE IN THE DETAILS..  MARTIN

PREVIOUS DISCUSSION...
AN UPPER-LEVEL TROUGH MOVING ACROSS THE WESTERN STATES WILL KEEP
MOST OF THE REGION WET AND UNSETTLED. EASTERN MONTANA WILL HAVE
MOIST SOUTH-SOUTHWESTERLY FLOW ALOFT THROUGH THE WEEKEND AS THE
TROUGH AXIS TRACKS ACROSS THE ROCKIES. THIS PATTERN TENDS TO BE
FAVORABLE FOR HIGHER PRECIPITATION AND ORGANIZED CONVECTION.

THE BEST TIME FRAME FOR CONVECTIVE DEVELOPMENT FOR NEMONT WILL BE
SATURDAY AFTERNOON AND EVENING... WITH HIGHEST PRECIPITATION
VALUES EXPECTED FOR THE SOUTHERN AND SOUTHEAST COUNTIES. AT THIS
POINT IN TIME MODEL GUIDANCE IS SHOWING CAPE VALUE AROUND
1200-1500 J/KG OVER MUCH OF THE SOUTHEAST WITH LI VALUES AROUND
-5. FORECAST SOUNDINGS ALSO SHOW PW VALUES NEAR 1 INCH WHICH IS
HIGHER THAN THE CLIMATIC NORMAL. SHOWER ACTIVITY WILL LIKELY TAPER
OFF DURING THE OVERNIGHT HOURS. AEC

BEGINNING SUNDAY...SEVERAL PINWHEELING BANDS OF SHOWERS AND
THUNDERSTORMS ARE LIKELY GIVEN VERY GOOD MODEL AGREEMENT. WHILE
ALL THE MODELS SHOW A WET SOLUTIONS...SOME INDICATE MORE QPF THAN
OTHERS. SYNOPTICALLY...NORTHEAST MONTANA WILL FIND ITSELF UNDER A
WELL-DEFINED UPPER LEVEL LOW PRESSURE TROUGH FROM SUNDAY THROUGH
TUESDAY MORNING. ALL LOCATIONS HAVE A VERY GOOD CHANCE OF GETTING
AT LEAST A WETTING RAIN. SOME LOCATIONS COULD EASILY GET MUCH MORE
THAN THAT. EXACT DETAILS ARE STILL TO FAR AWAY TO PIN DOWN AT THIS
TIME. THE GFS ADVERTISES THE MOST RAINFALL...BUT LATELY IT IS
CONSISTENT IN DOING SO...AND THE EC HAS BEGUN TO SHOW MORE QPF THAN
ITS OWN PREVIOUS RUN. WOULD EXPECT THIS TIME FRAME TO BE IN A
HEIGHTENED CONCERN FOR POSSIBLE FLOODING EFFECTS...BUT OF COURSE
IT IS TOO EARLY TO GET INTO ANY DETAILS AT THIS TIME.

TUESDAY THROUGH WEDNESDAY...A BIT OF A LULL BETWEEN SYSTEMS WILL
TEMPORARILY DRY THINGS OUT OVER NORTHEAST MONTANA BEFORE ANOTHER
LARGE LOW PRESSURE SYSTEM SLIDES IN FROM THE PACIFIC NORTHWEST.
THIS ALSO LOOKS LIKE A SLOW MOVING SYSTEM AND WOULD POTENTIALLY
BRING ANOTHER LENGTHY PERIOD OF UNSETTLED WEATHER THROUGH THAT
NEXT WEEKEND. BMICKELSON


&&

.AVIATION...
SCATTERED SHOWERS WILL CONTINUE THROUGH THE OVERNIGHT...WITH
PERHAPS A RUMBLE OF THUNDER. ADDITIONAL SHOWERS AND THUNDERSTORMS
ARE EXPECTED ON FRIDAY. CEILINGS AND VISIBILITIES MAY DROP DOWN
TO MVFR WITHIN THE STEADIEST SHOWER ACTIVITY. EASTERLY WINDS OF
AROUND 10 KTS ARE ANTICIPATED THROUGH THE TAF PERIOD. HIGHER GUSTS
ARE POSSIBLE WITH ANY THUNDERSTORMS. MALIAWCO


&&

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

&&

$$

WEATHER.GOV/GLASGOW