Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 141621
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
921 AM MST SUN FEB 14 2016

.SYNOPSIS...A MOIST NORTHWEST FLOW WILL DEVELOP OVER NORTHERN
UTAH TODAY AND LAST INTO MONDAY. HIGH PRESSURE ALOFT WILL REBOUND
ACROSS THE REGION TUESDAY THEN SHIFT EAST WEDNESDAY AHEAD OF THE
NEXT PACIFIC COLD FRONT.

&&

.DISCUSSION...NORTHWEST FLOW PREVAILS ACROSS THE INTERMOUNTAIN
WEST THIS MORNING. A 140KT 300MB JET EMBEDDED WITHIN THIS FLOW IS
NOTED ACROSS THE NORTHERN ROCKIES THIS MORNING...WITH THE NOSE OF
THIS FEATURE PROVIDING SUFFICIENT LIFT TO INDUCE LIGHT
PRECIPITATION ACROSS NORTHERN UT. PRECIPITATION BEGAN AS LIGHT
SNOW ACROSS MANY NORTHERN VALLEYS...HOWEVER AS DRIER AIR ALOFT HAS
BEGUN TO WORK INTO NORTHERN UT A LACK OF SATURATION WITHIN THE
SNOW-GROWTH ZONE IS RESULTING IN AREAS OF LIGHT FREEZING RAIN AS
WELL. UPDATED TO INCLUDE THIS THROUGH THE REMAINDER OF THE
MORNING...BEFORE PRECIPITATION QUICKLY WINDS DOWN BY EARLY
AFTERNOON AS THE JET AXIS SHIFTS EAST AWAY FROM THE AREA...AND THE
CURRENT FORECAST OF QUICKLY DIMINISHING POPS SEEMS REASONABLE.

THE OTHER QUESTION REMAINS THE EFFECT OF THE PASSING SYSTEM ON THE
INVERSIONS WHICH HAVE PLAGUED NORTHERN AND CENTRAL UT VALLEYS FOR
THE PAST WEEK OR SO. A COMBINATION OF COOLING ALOFT (700MB TEMPS
DOWN TO NEAR -6C THIS MORNING)...PRECIPITATION AND CLOUD COVER
WILL LIKELY ALLOW FOR SOME VERTICAL MIXING/DISPERSION OF THESE
STAGNANT AIRMASSES ACROSS NORTHERN UT TODAY...AND MODEL BUFR
SOUNDINGS SUGGEST LOW LEVEL LAPSE RATES EVEN APPROACH MOIST
ADIABATIC FOR A TIME THIS AFTERNOON. HOWEVER WARMING ALOFT WHICH
REDEVELOPS THIS AFTERNOON WILL RESULT IN AN INVERSION LAYER
REDEVELOPING NEAR CREST LEVEL THIS EVENING AND LOWERING OVERNIGHT.
SO...ALTHOUGH ITS NOT OUT OF THE QUESTION INVERSIONS WILL
COMPLETELY DISSIPATE ACROSS NORTHERN UT...THE MORE LIKELY SCENARIO
SEEMS TO BE SOME IMPROVEMENT IN AIR QUALITY TODAY BUT NOT A
COMPLETE DISPERSION OF THE STAGNANT AIRMASSES. FURTHER SOUTH
ACROSS CENTRAL UT WITH LESS COOLING ALOFT IT SEEMS MORE LIKELY THE
VALLEY INVERSIONS WILL REMAIN FULLY INTACT THROUGH THE MIDDLE OF
THE WEEK.

&&

.AVIATION...AT THE SLC TERMINAL...IFR CONDITIONS IN SNOW OR
SNOW PELLETS ARE EXPECTED TO PERSIST THROUGH THE MORNING. PRECIP
SHOULD TRANSITION TO RAIN OR A MIX OF RAIN AND SNOW BETWEEN 18Z AND
19Z...RESULTING IN MVFR CONDITIONS...BEFORE PRECIPITATION TAPERS OFF
BY LATE AFTERNOON...ALLOWING FOR VFR CONDITIONS TO PREVAIL.
SOUTHERLY WINDS ARE EXPECTED TO SHIFT TO THE NORTHWEST BETWEEN 19Z
AND 21Z...BUT THERE IS A 30 PERCENT CHANCE THIS SHIFT OCCURS LATER
THAN EXPECTED OR WINDS REMAIN SOUTHERLY THROUGHOUT THE DAY.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...NONE.
&&

$$

PUBLIC...SEAMAN
AVIATION...TRAPHAGAN

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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