000
FXUS65 KMSO 160239
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
839 PM MDT THU MAY 15 2008
UPDATE
MASSAGED A FEW MINIMUM TEMPERATURES FOR TONIGHT.
DISCUSSION
THE RIDGE OF HIGH PRESSURE WAS SHIFTING EASTWARD INTO
THE NORTHERN ROCKIES THIS EVENING. THE AIR MASS HAS WARMED BETWEEN
11 TO 20 DEGREES AS COMPARED TO YESTERDAY...INCLUDING HIGHER
ELEVATIONS. SKIES HAVE CLEARED AND WINDS ARE DIMINISHING THIS
EVENING. HAVE MADE ONLY A FEW TWEAKS TO MINIMUM TEMPERATURES FOR
TONIGHT...OTHERWISE THE FORECAST IS IN GOOD SHAPE.
AVIATION
CLEAR CALM CONDITIONS WILL PREVAIL ACROSS WESTERN
MONTANA AND NORTH-CENTRAL IDAHO THROUGH FRIDAY.
PREV DISCUSSION
/ISSUED 229 PM MDT THU MAY 15 2008/
..RECORD SETTING HEAT WAVE LEADING TO ENHANCED SNOW MELT AND
POTENTIAL FLOODING THIS WEEKEND...
DISCUSSION...A VERY STRONG UPPER LEVEL RIDGE CAN CLEARLY BE SEEN
BUILDING OVER THE PACIFIC NORTHWEST TODAY ON WATER VAPOR IMAGERY.
THE RIDGE WILL CONTINUE TO STRENGTHEN THROUGH THE WEEKEND LEADING
TO CLEAR SKIES WITH RECORD OR NEAR RECORD HIGH TEMPERATURES
SATURDAY AND SUNDAY AFTERNOON. FORECAST MODELS ARE SHOWING
SATURDAY AS THE HOTTEST DAY ALOFT WITH 850MB TEMPERATURES BETWEEN
24-26 DEGREES CELSIUS. BUT BELIEVE BETTER ATMOSPHERIC MIXING WITH
A SLIGHTLY LONGER PERIOD OF SUPERADIABATIC LAPSE RATES ON SUNDAY
WILL LEAD TO MAXIMUM TEMPERATURES EQUAL OR SLIGHTLY HOTTER THAN
SATURDAY'S VALUES. RIVERS AND STREAMS WILL BEGIN TO RISE
NOTICEABLY THIS WEEKEND AS HOT TEMPERATURES LEAD TO INCREASED
MELTING OF THE SNOW PACK IN THE MOUNTAINS. ON MONDAY FORECAST
MODELS CONTINUE TO SUGGEST THE RIDGE WILL BEGIN TO BREAK DOWN. BUT
TEMPERATURES WILL BE SLOW TO RESPOND AND STILL WELL ABOVE NORMAL
MONDAY AFTERNOON. CLOUDS WILL BE ON THE INCREASE AS THE MID AND
UPPER PORTIONS OF THE ATMOSPHERE BEGIN TO SLOWLY MOISTEN UNDER THE
DEVELOPING WESTERLY FLOW WITH DRY CONDITIONS PERSISTING IN THE
LOWER LEVELS THROUGH AT LEAST MONDAY NIGHT.
TUESDAY THROUGH FRIDAY...CONFIDENCE IN MODEL SOLUTIONS IN THE LONG
TERM IS LOW AS TIMING AND OVERALL WEATHER FEATURES ARE DIFFERENT.
TUESDAY LOOKS TO BE A TRANSITION DAY AS A TROUGH OF LOW PRESSURE
IS EXPECTED TO APPROACH THE NORTHERN ROCKIES INCREASING CLOUDS AND
BEGIN A COOLING TREND AND WITH A CHANCE OF SHOWERS OVER THE ID
PANHANDLE AND NORTHWEST MT. ON WEDNESDAY...ALTHOUGH THE TIMING OF
FEATURES ARE QUITE A BIT DIFFERENT FROM EACH MODEL IT LOOKS LIKE
WIDESPREAD SHOWERS CAN BE EXPECTED WITH TEMPERATURES COOLING TO
BELOW NORMAL VALUES. THE COOL AND SHOWERY REGIME IS ADVERTISED TO
CONTINUE THROUGH THE WEEKS END.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
SHORT TERM...MSJ
LONG TERM....FELSCH
AVIATION...MSJ
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