Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 282237
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
337 PM MST WED JAN 28 2015

.SYNOPSIS...HIGH PRESSURE WILL BUILD OVER THE FORECAST AREA
TONIGHT INTO THURSDAY. A RATHER MOIST STORM SYSTEM WILL IMPACT
PRIMARILY CENTRAL AND SOUTHERN UTAH THURSDAY NIGHT THROUGH
SATURDAY.

&&

.SHORT TERM (THROUGH 00Z SUNDAY)...HIGH PRESSURE STARTING TO BUILD
OVER THE FORECAST AREA THIS AFTERNOON AS THE WEAK WAVE EXITS THE
AREA. SATELLITE INDICATING SOME LINGERING CLOUDS OVER NORTHERN
UTAH...BUT ONLY A FEW ECHOES OVER THE GSL ON RADAR. ANY LINGERING
PRECIP WILL DIMINISH BY EARLY THIS EVENING.

THE RIDGE OVER THE AREA WILL BE SHORT LIVED...AS IT SHIFTS EAST
BEGINNING THURSDAY AFTERNOON AS A BROAD PACIFIC TROUGH MOVES ONTO
THE SOUTHERN CALIFORNIA COAST. AS THE CENTER MOVES INTO WESTERN
ARIZONA THROUGH SATURDAY MORNING IT WILL DRAW DEEP MOISTURE INTO
MUCH OF THE FORECAST AREA. BEST MOISTURE WILL BE OVER SOUTHERN
UTAH...WHERE PWS ARE EXPECTED TO RISE TO AROUND 0.6...AROUND THREE
STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME OF YEAR.

BEST DYNAMICS REMAIN SOUTH OF THE AREA WITH THE MAIN TROUGH.
HOWEVER...THERE SHOULD BE ENOUGH IN THE RATHER MOIST AIRMASS TO
RESULT IN WIDESPREAD PRECIP OVER CENTRAL AND SOUTHERN UTAH WITH
SNOW LEVELS AROUND 6500 TO 7000 FEET. IMPACTS SHOULD BE LIMITED
DUE TO THE HIGH SNOW LEVELS...BUT TOTALS MAY BE JUST ENOUGH TO
WARRANT A HIGH ELEVATION ADVISORY. PRECIP SHOULD BE LIMITED FOR
NORTHERN UTAH...BUT A BIT OF LIGHT VALLEY RAIN/MOUNTAIN SNOW IS
CERTAINLY NOT OUT OF THE QUESTION. THE SYSTEM IS PROGGED TO TRACK
SOUTH DURING THE DAY SATURDAY...BRINGING DRIER AIR BACK INTO UTAH
AND SOUTHWEST WYOMING.

&&

.LONG TERM (AFTER 00Z SUNDAY)...RIDGE BUILDS IN FROM THE
NORTHWEST BEHIND THE EXITING STORM SYSTEM. TEMPERATURES AT 700 MB
WARM TO NEAR 0C OR BETTER ACROSS MUCH OF THE CWA SUNDAY AFTERNOON
WHICH SHOULD HAVE NO PROBLEM BEING REALIZED IN THE MOUNTAINS BUT IS
ALWAYS A CHALLENGE FOR THE VALLEYS AS AN INVERSION WILL PLAY A ROLE
IN KEEPING THE TEMPS DOWN SOME. PROBABLY HAVE NOT GONE WARM ENOUGH
BUT WILL HAVE TIME TO PUSH UPWARDS AS THE WEEKEND APPROACHES.

THE RIDGE GETS FLATTENED BY A KIND OF ZONAL FLOW BY MONDAY WHICH
CONTAINS A COUPLE OF WEAK DISTURBANCES. THE GFS AND EC ARE SOMEWHAT
SIMILAR IN THE DEGREE OF COOLING AT 700 MB BUT THE EC IS ABOUT 2-3C
COLDER AT 500MB BY 18Z MONDAY MAKING IT THE MORE UNSTABLE MODEL YET
IT IS THE GFS THAT INDICATES SOME QPF ACROSS THE NORTHERN PORTION OF
THE CWA.  HAVE LEANED TOWARD THE GFS SOLUTION FIGURING THAT THERE
APPEARS TO BE ENOUGH INSTABILITY FOR A CHANCE OF LIGHT
PRECIPITATION. THIS ZONAL FLOW ON MONDAY CHANGES ORIENTATION TO MORE
NORTHWEST AS THE EASTERN PACIFIC RIDGE BEGINS TO BUILD TUESDAY
THROUGH WEDNESDAY. ANOTHER RIPPLE OR TWO MOVES THROUGH THIS
NORTHWEST FLOW WHICH SINKS FARTHER SOUTH INTO CENTRAL UTAH TUESDAY
AFTERNOON AND NIGHT. HAVE INCREASED THE POPS AND EXTENDED THEM A
LITTLE FARTHER SOUTH FOR THIS TUESDAY PERIOD AS THE GFS TREND HAS
MORE MOIST NORTHWEST FLOW ACROSS THE REGION. THE CANADIAN IS THE
COLDEST OF THE GLOBAL MODEL SOLUTIONS WITH MINUS 10C PUSHING IN
ACROSS THE NORTH. CHOSE THE GFS TO BASE TEMPERATURES AS IT WAS CLOSE
TO THE AVERAGE BETWEEN THE CANADIAN AND EC.

THE FINAL WAVE WEAKENS AS IT MOVES SOUTHEAST ACROSS THE CWA
WEDNESDAY SO PULLED BACK ON THE POPS A LITTLE FOR WEDNESDAY
AFTERNOON AS THE RIDGE BEGINS TO HAVE AN IMPACT ON AT LEAST THE
WESTERN PORTION OF THE CWA WHICH WILL SEE SOME STABILIZATION.


&&

.AVIATION...NORTHERLY FLOW IS EXPECTED TO REMAIN AT THE SLC TERMINAL
THROUGH MOST OF TONIGHT WITH A SWITCH TO SOUTHEAST LIKELY AFTER 11Z
BUT COULD SWITCH A FEW HOURS EARLIER. CIGS IN GENERAL ARE EXPECTED
TO GRADUALLY RISE ABOVE 7K FT AGL BY O2-03Z BUT THERE WILL BE TIMES
OF CIGS AT OR BELOW 6K FT AGL THROUGH 02Z.


&&

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

$$

SHORT TERM...TRAPHAGAN
LONG TERM/AVIATION...STRUTHWOLF

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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