382
FXUS65 KSLC 091139
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
439 AM MST MON NOV 9 2009
SYNOPSIS
A MILD SOUTHWEST FLOW WILL BECOME STRONGER THROUGH
MIDWEEK. A PACIFIC STORM SYSTEM WILL IMPACT THE GREAT BASIN FOR
THE LATTER PART OF THE WEEK.
DISCUSSION
FLAT RIDGING OVER THE WEST IS SHIFTING EAST THIS
MORNING AND THE FLOW ALOFT HAS BACKED AROUND TO SOUTHWEST. THE
FLOW WILL INCREASE TODAY THROUGH WEDNESDAY AS THE NEXT LARGE TROF
IN THE ERN PAC BEGINS TO EDGE INLAND.
SOUTHWEST WINDS SHOULD SURFACE IN THE MORE PRONE AREAS SUCH AS
SOUTHWEST UTAH THIS AFTERNOON BUT MOST OF THE NORTHERN AND EASTERN
VALLEYS WILL LIKELY NOT MIX MUCH.
THE ERN PAC TROF IS FORECAST TO BECOME POSITIVELY TILTED TUE AND
WED SLOWING ITS ADVANCE BUT THE INCREASING SOUTH WINDS WILL MIX
MORE AREAS TUE AND SHOULD SURFACE PRETTY MUCH EVERYWHERE WED.
THE 00Z EC THEN OPENS UP THE TROF AND ADVANCES THE COLD FRONT
ABOUT 1/3 OF THE WAY THRU UT BY 12Z THU AND OUT OF THE CWA BY 00Z
FRI. THE 00Z GFS MAINTAINED A MORE POS TILTED AND SPLIT FEATURE
BUT ALSO SHOWED THE COLD FRONT PAST SLC BY 12Z THU. THE 06Z GFS
WENT EVEN MORE TOWARDS THE EC IDEA ALTHO WAS STILL MORE SPLIT AND
STALLED THE COLD FRONT ACROSS NRN UT UNTIL THU NIGHT.
COMPARING THE 00Z MODEL RUNS TO THE PREV ONES POINTS TO THE EC
SOLUTION AS THE MORE STABLE AND THE FACT THAT THE GFS HAS TRENDED
THAT WAY WITH THE 00Z AND 06Z RUNS LENDS EVEN MORE CREDENCE TO
THAT SOLUTION. SO HAVE ADJUSTED THE GRIDS THAT WAY WITH HIGHER
POPS STARTING LATE WED NIGHT THRU THU THEN LOWERED POPS SOMEWHAT
THU NIGHT AND FRI.
THE AIRMASS IN EITHER SOLUTION IS COLD ENOUGH FOR SNOW TO MOST
VALLEY FLOORS BY THU AFTN OR FRI MORNING ALTHO BOTH MODELS SHOW IT
WOULD BE SHOWERY BY THAT TIME. SO THE THREAT OF SIGNIFICANT VALLEY
ACCUMULATION IS SMALL. MOST MOUNTAIN AREAS HAVE THE POTENTIAL TO
PICK UP ADVISORY LEVEL AMOUNTS BUT SUFFICIENT UNCERTAINTY REMAINS
TO PREVENT DETERMINING WHICH MOUNTAINS WOULD BE MOST FAVORED.
THE EC HAS A SMALL BUT POTENT SECOND TROF FOR SAT WHILE THE 06Z
GFS NOW HAS A GRAZING WAVE INSTEAD OF A RIDGE. SO KEPT NEAR CLIMO
POPS IN THE GRIDS THRU SAT NIGHT THEN DRIED IT OUT.
AVIATION
SURFACE WINDS AT THE SLC TERMINAL ARE EXPECTED TO SWITCH
TO THE NORTHWEST BETWEEN 18Z AND 20Z...WITH A 20 PERCENT CHANCE THAT
WINDS WILL REMAIN SOUTHERLY THROUGH 21Z. OTHERWISE...VFR CONDITIONS
WILL PREVAIL...AND ANY CEILINGS THAT FORM WILL BE WELL ABOVE 7000FT
AGL.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...NONE.
WILENSKY/SCHOENING
FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)
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