Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 182301
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
400 PM MST TUE NOV 18 2014

.SYNOPSIS...A STRONG UPPER LEVEL RIDGE OVER THE WEST COAST STATES
WILL SHIFT EAST INTO THE GREAT BASIN THROUGH WEDNESDAY. A SERIES OF
WEAKENING WEATHER DISTURBANCES WILL MOVE EAST ACROSS THE REGION LATE
IN THE WEEK...WITH A MUCH STRONGER SYSTEM EXPECTED FOR THE WEEKEND.

&&

.SHORT TERM (THROUGH 00Z SATURDAY)...A HIGH-AMPLITUDE RIDGE UPSTREAM
OF THE FORECAST AREA IS STILL MAKING ITS WAY INTO THE GREAT BASIN
THIS AFTERNOON. WITH UTAH ON THE LEADING EDGE OF THIS RIDGE...DRY
AND STABLE CONDITIONS WILL CONTINUE THROUGH TONIGHT. HIGH CLOUDS ARE
INCREASINGLY ENCROACHING ON THE AREA AT THIS TIME...SO EXPECT TO SEE
SOME INCREASE IN CLOUD COVER TONIGHT. SOME VALLEYS...INCLUDING THE
WASATCH FRONT FROM OGDEN SOUTH...SAW THE LOW LEVELS MIX A BIT BETTER
TODAY WHICH LED TO WARMER TEMPERATURES. HOWEVER...SOME OF THE
NORMALLY COLDER BASINS...INCLUDING THE CACHE VALLEY AND THE SALT
FLATS...ARE STILL STRUGGLING AND CURRENTLY SIT NEAR THE FREEZING
MARK. BECAUSE OF THE SOMEWHAT BETTER MIXING TODAY AND GENERAL
WARMING OF THE AIRMASS...EXPECT OVERNIGHT MINS TO BE A BIT WARMER
TONIGHT MOST AREAS...BUT STILL COLDER THAN NORMAL IN THE LOWER
VALLEYS.

THE RIDGE WILL START TO BREAK DOWN TOMORROW AS THE TROUGH CURRENTLY
EVIDENT ON WATER VAPOR IMAGERY OFF THE CALIFORNIA COAST HEADS INLAND
TOMORROW. THIS SACRIFICIAL TROUGH WILL WEAKEN AS IT CROSSES THE
GREAT BASIN...BUT COULD PRODUCE SOME LIGHT PRECIPITATION MAINLY
ACROSS THE NORTH TOMORROW NIGHT INTO THURSDAY. GENERAL TREND CALLS
FOR GRADUALLY INCREASED MIXING OF THE AIRMASS AND THUS WARMING
TREND. AS A RESULT...SNOW LEVELS 5-6KFT ARE GENERALLY EXPECTED...BUT
SOME OF THE COLDER VALLEYS MAY STILL FAIL TO MIX ENOUGH TO CHANGE TO
RAIN. ALTHOUGH THE PRECIPITATION AMOUNTS DO NOT LOOK VERY
PROMISING...THIS IS JUST THE FIRST IN A SERIES OF STORM SYSTEMS
EXPECTED TO IMPACT THE AREA THROUGH THE WEEKEND.

THE NEXT TROUGH THURSDAY NIGHT THROUGH FRIDAY LOOKS TO TAKE A MORE
SOUTHERLY TRACK...AS IT IS STILL FORECAST TO STRONGLY SPLIT AS IT
MOVES INLAND. EACH SUCCESSIVE MODEL RUN SEEMS TO BE MORE AGGRESSIVE
WITH THIS SPLIT. AS IT STANDS NOW...SOUTHERN UTAH IS EXPECTED TO SEE
SOME LIGHT PRECIPITATION WITH SNOW LEVELS NEAR 6KFT WITH THIS
SYSTEM...BUT WITH THE WAY THE MODELS ARE TRENDING...WOULD NOT BE
SURPRISED IF MOST OF THE PRECIPITATION FALLS SOUTH OF THE FORECAST
AREA.

&&

.LONG TERM (AFTER 00Z SATURDAY)...WARM ADVECTION INTENSIFIES FRIDAY
EVENING AHEAD OF A MOIST MULTI-PART WINTER STORM APPROACHING UTAH
FROM THE NORTHWEST. PRECIPITATION IS EXPECTED TO DEVELOP SATURDAY
MORNING IN THE NORTH AS VALLEY RAIN AND MOUNTAIN SNOW...SPREADING
SOUTHWARD AS THE DAY PROGRESSES. THE ACCOMPANYING COLD FRONT BLASTS
THROUGH THE STATE SATURDAY AFTERNOON...THOUGH THE MUCH COLDER AIR
LAGS SEVERAL HOURS BEHIND THE FRONT. THUS SNOW LEVELS WILL LIKELY
RESIST PLUMMETING TO THE VALLEY FLOORS UNTIL LATE SATURDAY
NIGHT/EARLY SUNDAY MORNING. A LONG PERIOD OF INTENSE COLD ADVECTION
AT 500MB ON SATURDAY ATOP WARM ADVECTION AT 700MB WILL FURTHER SET
THE STAGE FOR A SIGNIFICANT OROGRAPHIC EVENT IN THE NORTHERN
MOUNTAINS THIS WEEKEND.

THE COLDEST AIR ARRIVES BY SUNDAY IN CONFIDENT NORTHWEST FLOW AND
CONTINUING MOIST ENVIRONMENT. THIS COMBINATION...ATOP THE STILL-WARM
GREAT SALT LAKE...HOLDS GOOD POTENTIAL FOR A LAKE-EFFECT EVENT IN
THE SALT LAKE AND TOOELE VALLEYS EARLY SUNDAY MORNING. A STRONG VORT
MAX ACCOMPANIED BY 145 KT JET SHOOTING INTO SW UTAH ON SUNDAY WILL
ENCOURAGE CONTINUED SNOWFALL FOR THE CENTRAL MOUNTAINS AS WELL. SNOW
MAY LINGER IN NORTHERN MOUNTAINS ON MONDAY AND TUESDAY...AS THE
LATEST GFS USHERS IN ANOTHER ROUND OF WARM ADVECTION IN THE STILL-
MOIST ENVIRONMENT.

&&

.AVIATION...NORTHWESTERLY WINDS AT THE SLC TERMINAL WILL SHIFT TO
THE SOUTHEAST AROUND 03Z.

&&

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

$$

CHENG/VERZELLA

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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