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AREA FORECAST DISCUSSION

 
 FXUS65 KSLC 012322
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
422 PM MST SUN MAR 1 2015

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

&&

.SHORT TERM (THROUGH 00Z THURSDAY)...AN UPPER LOW SPINNING ALONG
THE CALIFORNIA COAST THIS AFTERNOON...WITH A DOWNSTREAM JET
POSITIONED FROM SOUTHERN CA NORTHEASTWARD ACROSS SOUTHERN UT.
LARGE SCALE ASCENT WITHIN THE ENTRANCE REGION COUPLED WITH STRONG
MOISTURE ADVECTION ASSOCIATED WITH A SUBTROPICAL MOISTURE TAP IS
RESULTING IN WIDESPREAD PRECIPITATION FROM SOUTHERN CA THROUGH
THE LOWER CO RIVER VALLEY. THIS AND INTO SOUTHERN UT. AS FORCING
INCREASES OVERNIGHT ACROSS SOUTHERN UT IN RESPONSE TO A VORT LOBE
EJECTING FROM THIS MEAN LOW POSITION...PRECIPITATION WILL INCREASE
IN COVERAGE AND INTENSITY...SLOWLY SPREADING INTO CENTRAL UT AND
EVENTUALLY PORTIONS OF NORTHERN UT BY SUNRISE MONDAY. THE ABSENCE
OF A STRONG SURFACE HIGH ACROSS THE REGION SUPPORTS RISING SNOW
LEVELS OVERNIGHT INTO THE DAY MONDAY ACROSS THE SOUTH AS A MORE
MILD AIRMASS SPREADS NORTHWARD. AS SUCH MAY SEE SNOW LEVELS RISE
ABOVE 5000 FEET OVERNIGHT ACROSS THE SOUTH...AND PERHAPS ABOVE
6000 FEET DURING THE DAY MONDAY DEPENDING ON PRECIP INTENSITY.

WENT AHEAD AND UPGRADED THE SOUTHERN MOUNTAINS TO A WINTER STORM
WARNING WHERE SNOWFALL SHOULD BE HEAVIEST. ITS POSSIBLE NORTHERN
PORTIONS OF SOUTH CENTRAL UT /ZONE 20/ MAY REMAIN SNOW INTO THE
DAY MONDAY AND REACH WARNING CRITERIA...BUT THESE POCKETS WILL
LIKELY REMAIN ISOLATED. ELSEWHERE EXPANDED THE GOING WINTER WX
ADVISORY INTO THE SAN RAFAEL SWELL REGION ABOVE 5500 FEET...WITH
THE MAIN CONCERN BEING TRAVEL ALONG THE HIGHER PASSES OF I-70.
ALSO EXPANDED THIS ADVISORY INTO THE SOUTHERN WASATCH AND WESTERN
UINTA RANGES WHERE SNOWFALL SHOULD BEGIN DURING THE PRE-DAWN HOURS
MONDAY.

PRECIPITATION WILL LINGER INTO THE MORNING HOURS MONDAY ACROSS
MUCH OF UTAH SOUTH OF I-80...HOWEVER ANY SNOWFALL WHICH OCCURS IN
THE NORTHERN VALLEYS WILL LIKELY REMAIN LIGHT...WHILE RISING SNOW
LEVELS IN THE SOUTH SHOULD ALLOW MOST LOCATIONS TO SWITCH OVER TO
RAIN BELOW ROUGHLY 6000 FEET...ESPECIALLY EAST OF THE I-15
CORRIDOR. AS THIS EJECTING LOBE QUICKLY MOVES EAST DURING THE DAY
MONDAY WHICH MAY BRING A LULL TO PRECIPITATION DURING THE
AFTERNOON AND EVENING HOURS.

A COLDER NORTHERN STREAM SHORTWAVE IS FORECAST TO DIG THROUGH
NORTHERN UT LATE MONDAY NIGHT INTO TUESDAY MORNING BRINGING A
MUCH COLDER AIRMASS SOUTH INTO THE AREA. EXPECT TO SEE A PERIOD OF
SNOW ACROSS BOTH THE HIGHER TERRAIN OF NORTHERN UT AS WELL AS THE
NORTHERN VALLEYS...WHICH MAY IMPACT THE MORNING COMMUTE ALONG THE
WASATCH FRONT. THIS SYSTEM WILL QUICKLY SPREAD INTO SOUTHERN UT
DURING THE AFTERNOON BEFORE PRECIP ENDS ACROSS THE REGION BY
TUESDAY NIGHT. WITH 700MB TEMPS NEAR -15C DURING THE AFTERNOON
TUESDAY TEMPERATURES ACROSS THE NORTHERN VALLEYS WILL LIKELY
REMAIN IN THE 30S...WITH ONLY SLIGHT WARMING FOR WEDNESDAY.

&&

.LONG TERM (AFTER 00Z THURSDAY)...RIDGE BUILDING INTO THE GREAT
BASIN THURSDAY YIELDING MOSTLY SUNNY SKIES WITH A WARMING TREND. BY
FRIDAY THE EC AND THE OPERATIONAL GFS SHOW A WEAK BRUSH BY
DISTURBANCE MOVING INTO WYOMING BUT THE GFS ENSEMBLE DOES NOT SHOW
THIS DISTURBANCE. BECAUSE THE OPERATIONAL IS WEAKER THAN ITS
PREVIOUS RUN HAVE LEANED TOWARD THE ENSEMBLE SOLUTION WHICH KEEPS
POPS OUT OF THE EXTENDED. LITTLE CHANGE IN TEMPERATURE IS EXPECTED
FROM FRIDAY THROUGH SUNDAY AS THE FLOW REMAINS NORTHWEST WITH H7
TEMPERATURES NEARLY UNCHANGED. OVERALL PATTERN SHIFT BACK TO A RIDGE
IN THE WEST SEEMS TO BE WHAT THE GLOBAL MODEL SOLUTIONS ARE HEADING
TOWARDS IN THE LONG RANGE.

&&

.AVIATION...THE SLC TERMINAL WILL SEE VFR CONDITIONS THROUGHOUT THIS
EVENING WITH CIGS STAYING AT OR ABOVE 7K FT AGL UNTIL ABOUT 04Z.
CIGS COULD LOWER TO BELOW 7K FT AGL AT TIMES BEFORE 04Z. NORTHWEST
WINDS ARE EXPECTED TO PREVAIL THROUGH 04Z BEFORE SHIFTING TO THE
SOUTHEAST. THERE IS A 30 PERCENT CHANCE OF WINDS REMAINING NORTHERLY
THROUGH THE NIGHT. LIGHT SNOW IS POSSIBLE BETWEEN 12 AND 15Z.

&&

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

WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 4 PM MST
TUESDAY FOR UTZ008-009.

WINTER WEATHER ADVISORY UNTIL 4 PM MST TUESDAY FOR UTZ010-517.

WINTER STORM WARNING UNTIL 4 PM MST TUESDAY FOR UTZ518.

WY...NONE.
&&




PUBLIC...
AVIATION...

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)