Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 021246
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
546 AM MST MON MAR 2 2015

.SYNOPSIS...AN UPPER LEVEL TROUGH WILL LINGER OVER THE GREAT
BASIN TODAY THROUGH TONIGHT THEN SHIFT EAST LATE TUESDAY. A
DRYING AND WARMING TREND WILL FOLLOW FOR THE REMAINDER OF THE
WEEK.

&&

.SHORT TERM (THRU 00Z THU)...HEAVY PRECIP EVENT UNDER WAY ACROSS
THE CWA IN THE VERY MOIST SOUTHERLY FLOW EAST OF AN UPPER LOW JUST
OFF THE SRN CA COAST. GOOD JET SUPPORT HAS ASSISTED THE WARM
FRONT LIFTING THRU THE CWA OVERNIGHT AND WATER AMOUNTS OVER AN
INCH IN THE LAST 12 HOURS ARE SHOWING UP ON SOME OF THE SNOTEL
SITES IN THE SRN MTNS.

THE AIRMASS THIS MORNING IS ABOUT AS WARM AS IT IS FORECAST TO
GET IN THIS EVENT AND IT WILL STAY WARM THRU MIDDAY BEFORE COOLER
AIR STARTS SPREADING IN FROM THE WEST.

UNDER THIS MILD AIRMASS VALLEY IMPACTS SO FAR APPEAR TO BE VERY
DEPENDENT ON SNOW INTENSITY WITH THE FEW CAMS UNDER LIGHTS
SHOWING ROADS BECOMING SNOW COVERED DURING PERIODS OF HEAVIER SNOW
AND MELTING OFF AS SOON AS INTENSITIES DROP OFF. EXPECT THIS
PATTERN TO PERSIST INTO THIS MORNING WITH EVEN LESS IMPACT ONCE
WEAK SOLAR HEATING STARTS FILTERING THRU THE CLOUDS AND SURFACE
TEMPERATURES START TO CLIMB. AS A RESULT HAVE NOT EXPANDED THE
WINTER WEATHER ADVISORIES NORTHWARD AT THIS TIME.

THE CA LOW EJECTS THRU NV TODAY AND INTO WRN UT LATE TODAY. THIS
SENDS THE MOISTURE PLUME AND THE JET OFF TO THE EAST BY LATE AFTN
WITH PRECIP TAPERING OFF SOUTH AND EAST. THE UPPER TROF DOES
ENHANCE PRECIP ACROSS WESTERN UT THRU THIS EVE AND WITH COLDER AIR
MOVING IN PRECIP SHOULD BECOME ALL SNOW AND START ACCUMULATING IN
THE WRN VALLEYS.

MODELS INDICATE A LULL IN THE PRECIP OVERNIGHT BEFORE IT STARTS UP
AGAIN BEFORE DAYBREAK TUE AS A LAST COLD SHORT WAVE DROPS INTO
THE MEAN TROF. THIS MAINLY IMPACTS THE NRN MTNS AND NWRN VALLEYS
IN THE MORNING THEN SHIFTS INTO SWRN UT IN THE AFTN BUT WEAKENS AS
IT HEADS SOUTH. THIS FALLS AS SNOW AND THE COLDER AIRMASS WOULD
ALLOW IT TO STICK TO ALL SURFACES LIKELY IMPACTING THE COMMUTE FOR
THE WASATCH FRONT AND BACK TUE MORNING.

THE WHOLE TROF MOVES EAST BY WED MORNING WITH A CHILLY BUT DRY DAY
EXPECTED WED.

&&

.LONG TERM (AFTER 00Z THURSDAY)...MODEL TRENDS REMAIN SIMILAR RUN TO
RUN REGARDING THE POTENTIAL OF A WEAK WAVE GRAZING NORTHERN UTAH
FRIDAY NIGHT INTO SATURDAY. PRIMARY DIFFERENCE BETWEEN THE GFS
/NO WAVE/...AND THE ECMWF /GRAZING WAVE/ ARE SUBTLE DIFFERENCES OF
THE WEST COAST RIDGE AXIS PLACEMENT AND EVOLUTION OF SHORT WAVE
ENERGY OUT OF THE GULF OF AK. CONTINUE TO MAINTAIN A DRY FORECAST AS
EVEN THE ECMWF IS QUITE BENIGN W/THIS FEATURE...AND NEITHER MODEL
HAS BUDGED THAT MUCH IN DEPICTION OVER THE LAST FEW RUNS.

OVERALL...THE MOST NOTABLE CHANGES TO SENSIBLE WEATHER IN THE LONG
TERM WILL BE A NET DRYING AND WARMING TREND FOR ALL AREAS ACROSS THE
FORECAST AREA MID/LATE WEEK. A RETURN TO WELL ABOVE NORMAL TEMPS
CAN BE EXPECTED BY NEXT WEEKEND AS THE RETURN OF A LARGE SCALE
WEST COAST RIDGE LOOKS TO MAINTAIN A VERY DRY AND STABLE
NORTHWESTERLY FLOW ALOFT.

&&

.AVIATION...CIGS AT THE KSLC TERMINAL ARE EXPECTED TO CONTINUE TO
LOWER THIS MORNING WITH SUB 6000FT AGL LEVELS PREVAILING AGAIN BY
16Z. LIGHT AND VARIABLE TO LIGHT SOUTHEAST WINDS ARE EXPECTED TO
BECOME PREVAILING NORTHWEST BETWEEN 15-17Z...WITH LIGHT RAIN
SHOWERS BECOMING MORE LIKELY THIS AFTERNOON.

A THREAT OF ACCUMULATING SNOW WILL INCREASE AFTER 03Z
TONIGHT...WITH POTENTIAL FOR SOME ACCUMULATING SLUSH ON UNTREATED
SURFACES AFTER 06Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER WEATHER ADVISORY UNTIL 9 PM MST THIS EVENING FOR UTZ012-
     013-016-020.

     WINTER WEATHER ADVISORY UNTIL 4 PM MST TUESDAY FOR UTZ008>010-
     517.

     WINTER STORM WARNING UNTIL 4 PM MST TUESDAY FOR UTZ518.

WY...NONE.
&&

$$

SHORT TERM...WILENSKY
LONG TERM/AVIATION...MERRILL

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)



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