Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 251132
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
432 AM MST WED FEB 25 2015

.SYNOPSIS...THE NORTHWEST FLOW ALOFT ACROSS THE GREAT BASIN WILL
BRING A SERIES OF INCREASINGLY STRONG WEATHER DISTURBANCES INTO
UTAH THROUGH THURSDAY. AN ENERGETIC AND SLOW MOVING STORM SYSTEM
WILL AFFECT THE REGION LATE FRIDAY THROUGH THE UPCOMING WEEKEND.

&&

.SHORT TERM (THROUGH 06Z SATURDAY)...THE MEAN UPPER RIDGE
POSITIONED ACROSS THE EASTERN PACIFIC WILL MAINTAIN A DOWNSTREAM
NORTHWEST FLOW ACROSS THE GREAT BASIN THE NEXT COUPLE OF DAYS.
LOOKING AT TWO OR THREE EMBEDDED SHORTWAVES TO CROSS UTAH THROUGH
THURSDAY. THE FIRST SHORTWAVES CURRENTLY OVER FAR NORTHERN UTAH
WILL GENERATE CLOUDS BUT NO REAL PRECIP AS LIFT WILL BE WEAK AND
FAIRLY SHALLOW.

THE NEXT SHORTWAVE WILL REACH FAR NORTHERN UTAH AND SOUTHWEST
WYOMING BY LATE THIS AFTERNOON OR EARLY THIS EVENING. THIS SECOND
FEATURE WILL EXHIBIT GOOD LOW-LEVEL COLD ADVECTION WITH MODEST
MID-LEVEL COOLING AND ADEQUATE MOISTURE. LIGHT PRECIP WILL
CONCENTRATE IN THE AREA OF BEST LIFT OVER THE NORTHERN WASATCH
MOUNTAINS...SOUTHWEST WYOMING AND INTO THE NORTH SLOPES OF THE
UINTAS THIS EVENING.

THE THIRD SHORTWAVE LOOKS TO BE THE BEST OF THREE AS IT ARRIVES
OVER NORTHWEST UTAH LATE TONIGHT...THEN TRACKS SOUTHEAST THROUGH
UTAH THURSDAY. INCREASINGLY DEEP AND MOIST WARM ADVECTION WILL
LEAD THIS FEATURE INTO NORTHERN UTAH LATE TONIGHT/EARLY THURSDAY.
LIGHT PRECIP COULD START AS EARLY AS LATE TONIGHT OVER NORTHWEST
UTAH...WITH A FAIRLY RAPID INCREASE IN INTENSITY AND AREAL
COVERAGE OF PRECIP ACROSS NORTHERN AND WESTERN UTAH THURSDAY
MORNING WITH THE ARRIVAL OF THE SHORTWAVE. SEVERAL INCHES OF SNOW
OF SNOW WILL ACCUMULATE OVER THE NORTHERN MOUNTAINS...WITH SOME
TRAVEL IMPACTS EXPECTED DURING THE MORNING COMMUTE. THE NORTHERN
AND CENTRAL PORTIONS OF THE URBAN CORRIDOR MAY ALSO SEE TRAVEL
IMPACTS FROM ROAD SLUSH IF SNOWFALL RATES ARE SUFFICIENTLY HIGH
ENOUGH DURING THE COMMUTE. SNOW WILL LIKELY CONTINUE INTO THE
NORTHERN AND CENTRAL MOUNTAINS AS A MOIST COLD ADVECTION NORTHWEST
FLOW CONTINUES THROUGH EARLY THURSDAY EVENING.

A NEW SHORTWAVE DIVING SOUTH ALONG THE PACIFIC NORTHWEST COAST
FRIDAY WILL EVOLVE INTO A CLOSED LOW OVER NORTHERN CALIFORNIA AND
NORTHWEST NEVADA AS IT EXITS OREGON LATE FRIDAY. THIS
STRENGTHENING STORM WILL LEAD TO A SIGNIFICANT WINTER STORM FOR
PORTIONS OF THE FORECAST AREA HEADING INTO THE UPCOMING WEEKEND.
SEE THE LONG TERM DISCUSSION FOR FURTHER DETAILS.

&&

.LONG TERM (AFTER 06Z SATURDAY)...THE DEEP TROUGH IS FORECAST TO DIG
FURTHER SOUTH THROUGH THE DAY SATURDAY AND CLOSE OFF INTO A VERY
LARGE CLOSED LOW OVER THE GREAT BASIN. PRECIPITATION ACROSS THE
FORECAST AREA CONTINUES TO LOOK QUITE PROMISING THROUGH THE
WEEKEND...ESPECIALLY ACROSS THE SOUTHERN HALF OF UTAH. THIS SYSTEM
IS VERY SIMILAR TO THE STORM EARLIER THIS WEEK IN SEVERAL
RESPECTS...MOST NOTABLY THE LONG-DURATION PRECIPITATION IN THE
SOUTH...AND THE CHANCE FOR STRONG DOWNSLOPE/CANYON WINDS IN THE
NORTH. HAVE INCREASED THESE EASTERLY WINDS ACROSS NORTHERN UTAH AND
SOUTHWEST WYOMING FOR SATURDAY NIGHT...AS MODELS ARE PRODUCING AN
IMPRESSIVE EASTERLY MSLP GRADIENT THE LATTER HALF OF SATURDAY AND
INTO SUNDAY. THESE WINDS WILL HAVE TO BE RAMPED UP MORE IF THIS
SOLUTION HOLDS FOR SEVERAL RUNS.

THE STORM LOOKS TO EXIT THE REGION A LITTLE MORE SLOWLY THAN
PREVIOUS RUNS INDICATED...SO HAVE INCREASED POPS A BIT FOR LINGERING
SHOWERS SUNDAY NIGHT AND MONDAY. THE ACTIVE PATTERN CONTINUES ON
TUESDAY AS YET ANOTHER TROUGH DROPS INTO THE REGION FROM THE NORTH-
NORTHWEST. THIS TROUGH LOOKS TO HAVE A COLDER AIRMASS AND PERHAPS A
MORE DIRECT HIT ON NORTHERN UTAH. HOWEVER...MODEL TRENDS HAVE
GENERALLY BEEN TO TAKE THIS SYSTEM A BIT FURTHER SOUTH AND PERHAPS
FURTHER WEST....PARTICULARLY IN THE ECMWF...SO WATCH FOR THE
POSSIBILITY THAT THIS STORM COULD TAKE A SOMEWHAT SIMILAR TRACK TO
THE TWO MAJOR STORMS BEFORE IT.

&&

.AVIATION...CEILINGS AT THE SLC TERMINAL IN THE 7-10KFT RANGE AS OF
11Z ARE EXPECTED TO MOVE SOUTH OF THE AREA BETWEEN 14Z AND 18Z.
THERE IS A 20 PERCENT CHANCE OF CEILINGS BELOW 7000FT THROUGH THE
DAY...AS A WEAK WEATHER DISTURBANCE MOVES THROUGH THE AREA...BUT
MOST SHOWERS AND LOWER CLOUDS SHOULD REMAIN EAST OF THE TERMINAL.
WINDS WILL LIKELY TURN TO THE NORTHWEST BETWEEN 15Z AND
18Z...BECOMING STRONGER AFTER 18Z.

&&

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

$$

SHORT TERM...CONGER
LONG TERM/AVIATION...SCHOENING

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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