FXUS65 KTFX 260440
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
940 PM MST WED NOV 25 2009
.UPDATE...
A QUIET WEATHER NIGHT ACROSS THE CWA WITH ONLY SOME UPPER CLOUDS
MOVING ACROSS THE TOP OF THE RIDGE THAT HAS FOUND A HOME OVER THE
WESTERN US. EXPECT BREEZY CONDITIONS TO CONTINUE THROUGH THE NIGHT
FOR LOCATIONS CLOSE TO THE EASTERN SLOPES OF THE ROCKIES. NO MAJOR
CHANGES TO THE FORECAST. ONLY A FEW COSMETIC TWEAKS TO MATCH UP A
BIT BETTER WITH OBSERVATIONS AND NEIGHBORS.
&&
.AVIATION
UPDATED 0439Z.
AN UPPER LEVEL HIGH PRESSURE RIDGE OVER THE REGION WILL SLOWLY MOVE
EAST DURING THE NEXT 24 HOURS. A SHORT WAVE WILL MOVE ACROSS
SOUTHERN CANADA TONIGHT AND THIS WILL KEEP STRONG...GUSTY WINDS
ACROSS THE NORTHERN ROCKIES AND ADJACENT PLAINS THROUGH THE
NIGHT...AND STRONG WINDS WILL AGAIN BECOME GUSTY THURSDAY AFTERNOON
ACROSS THE PLAINS. VFR CONDITIONS WILL PREVAIL DURING THE NEXT 24
HOURS.
&&
.PREV DISCUSSION...
/ISSUED 414 PM MST WED NOV 25 2009/
SHORT TERM...
TONIGHT AND THANKSGIVING DAY...A FEW HIGH CLOUDS IN CONJUNCTION
WITH A DEVELOPING CHINOOK ARCH WILL MOVE OVER NORTH-CENTRAL MONTANA
THIS EVENING AS MOISTURE SPILLS OVER AN UPPER-LEVEL RIDGE. VERY
STRONG GAP WINDS THAT HAVE PERSISTED OVER MARIAS PASS THROUGHOUT
THE DAY WILL CONTINUE THROUGH THIS EVENING BUT BEGIN TO SUBSIDE
LATER THIS EVENING AS THE PRESSURE GRADIENT RELAXES.
NEVERTHELESS...GUSTY WEST-SOUTHWESTERLY WINDS WILL PERSIST ALL
ACROSS THE ROCKY FRONT AND ADJACENT NORTH-CENTRAL PLAINS AS
SEVERAL SHORTWAVES FLATTEN THE UPPER-LEVEL RIDGE OVERNIGHT. WINDS
ARE EXPECTED TO REMAIN BELOW HIGH WIND CRITERIA SO HIGHLIGHTS
SHOULD NOT BE NEEDED THROUGH THANKSGIVING BUT WILL CONTINUE TO
MONITOR. STRONG DOWNSLOPING WINDS WILL KEEP TEMPERATURES ABOVE
AVERAGE ONCE AGAIN ON THANKSGIVING WITH HIGHS 20 TO 25 DEGREES
ABOVE SEASONAL AVERAGES OVER SOME AREAS.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...UNSETTLED WESTERLY FLOW WILL
CONTINUE THROUGH THE FORECAST PERIOD WITH SOME UNCERTAINTY IN THE
TIMING AND INTENSITY OF OUR NEXT SHORTWAVE TROUGH. DRY CONDITIONS
ARE EXPECTED ACROSS THE FORECAST AREA ON THURSDAY NIGHT THEN AS
OUR NEXT SHORTWAVE TROUGH MOVES INTO THE PACIFIC NORTHWEST
MOISTURE WILL BEGIN TO MOVE OVER THE CONTINENTAL DIVIDE SO HAVE
RAISED POPS ALONG THE ROCKY MOUNTAIN FRONT ON FRIDAY AFTERNOON. BY
FRIDAY NIGHT...TROUGH IS EXPECTED TO MOVE INTO THE INTERIOR
PACIFIC NORTHWEST AND DEEPEN. MODELS ARE CONSISTENT IN SPLITTING
THIS TROUGH WITH A DEVELOPING LOW OVER NORTHERN CALIFORNIA AND
THEN THE NORTHERN SHORTWAVE MOVING THROUGH MONTANA AND IDAHO. EC
SEEMS TO BE THE WETTEST MODEL WITH THE GFS FOLLOWING CLOSE BEHIND
BUT AM NOT CONFIDENT THAT THERE WILL BE SUFFICIENT MOISTURE OVER
THE FORECAST AREA. CURRENT THINKING IS THAT THE SOUTHERN LOW WILL
WRAP IN MAJORITY OF PACIFIC MOISTURE WHICH MAY LEAVE OUR PORTION
WITH LESS MOISTURE. ALSO...THIS IS A FAST-MOVING SYSTEM WHICH WILL
LIMIT PRECIP CHANCES AS WELL. NEVERTHELESS...UPPER-LEVEL JET MAX
AND MODEST DYNAMICS SHOULD FAVOR OROGRAPHIC PRECIPITATION WITH
LIGHT ACCUMULATING SNOW POSSIBLE IN THE HIGHER ELEVATIONS ALONG
THE ROCKY MOUNTAIN FRONT AND SOUTHWEST MONTANA LATE FRIDAY THROUGH
SATURDAY MORNING. AT THIS TIME...WINTER HIGHLIGHTS ARE NOT
ANTICIPATED BUT WILL CONTINUE TO MONITOR. OVER THE VALLEYS AND
PLAINS...MILD TEMPERATURES SHOULD ALLOW FOR A RAIN AND SNOW MIX
DURING THIS TIME FRAME. DRIER AND COLDER AIR WILL MOVE IN ONCE THE
SHORTWAVE MOVES EASTWARD BY SATURDAY MORNING. MLS
LONG TERM...
SATURDAY AND SUNDAY...
UPPER LEVEL TROUGH PUSHES THROUGH THE REGION SATURDAY HELPING TO
DRAW DOWN COOLER AIR INTO THE REGION...SURFACE HIGH WORKS EAST FROM
THE PACNW COAST. SOME DECENT LAPSE RATES THROUGH THE AFTERNOON AND
EVENING WITH JUST ENOUGH OF MOISTURE TO ALLOW FOR SOME SCTD SNOW
SHOWERS ACROSS THE AREA. UPPER LEVEL RIDGING WILL WORK INTO THE AREA
BY EARLY SUNDAY...AND LINGER INTO THE START OF THE WORK WEEK. DRYING
CONDITIONS FROM SATURDAY EVENING INTO SUNDAY...NO PRECIP LIKELY ON
SUNDAY INTO MONDAY. TEMPS WILL BE FAIRLY SEASONAL ON
SATURDAY...SLIGHTLY WARMER THAN AVERAGE ON SUNDAY.
MONDAY THROUGH WEDNESDAY..
RIDGING STARTS TO PUSH OUT OF THE REGION ON MONDAY AS THE NEXT
SYSTEM DROPS INTO AND THROUGH THE TREASURE STATE LATE MONDAY INTO
TUESDAY. GUSTY WINDS WILL BE LIKELY MONDAY NIGHT INTO
TUESDAY...POSSIBLE HEADLINES FOR THE WINDS ALONG THE NORTHERN ROCKY
MTN FRONT RANGE. SIGNIFICANT MOISTURE SEEN ALONG AND JUST BEHIND THE
TROUGH AS IT MOVES THROUGH...GOOD AGREEMENT THAT THE MOISTURE WILL
BE THERE BETWEEN THE EURO/GFS/GFS ENSEMBLE MEAN...THEREFORE HAVE
BUMPED UP POPS SOME...AND IF TREND CONTINUES THEN AN AREA WIDE SNOW
MAY BE POSSIBLE TUESDAY. ABOVE NORMAL TEMPS MONDAY...AS THE FRONT
PUSHES THROUGH TUESDAY THAT COULD BE THE START OF A SIGNIFICANT
COLDER PERIOD THAT MAY LAST INTO NEXT WEEKEND. MODEST UNCERTAINTY
FOR THIS POSSIBILITY...BUT SIGNALS ARE HEADING IN THIS DIRECTION AS
VERY COLD AIRMASS IN ALASKA/NW CANADA LOOKS TO BE ON THE MOVE NEXT
WEEK. SOMETHING TO DEFINITELY KEEP AN EYE ON OVER THE NEXT FEW
DAYS. --SCHOTT
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 38 58 35 52 / 0 0 0 10
CTB 36 56 33 48 / 0 0 0 10
HLN 29 50 26 48 / 0 0 0 20
BZN 20 42 18 45 / 0 0 0 20
WEY 13 38 13 36 / 0 0 0 30
DLN 23 45 21 43 / 0 0 0 20
HVR 30 60 29 53 / 0 0 0 10
LWT 31 58 30 53 / 0 0 0 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GUSTAFSON
LONG TERM...SCHOTT
AVIATION...ZELZER
WEATHER.GOV/GREATFALLS
