Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 232205
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
405 PM MDT THU APR 23 2015

.SYNOPSIS...AN UNSETTLED WEATHER PATTERN WILL REMAIN OVER THE
FORECAST AREA THROUGH FRIDAY. A COLD AND ENERGETIC PACIFIC STORM
SYSTEM WILL IMPACT THE REGION THIS WEEKEND. HIGH PRESSURE WILL
RETURN FOR EARLY NEXT WEEK.


&&

.SHORT TERM (THROUGH 00Z MONDAY)...SHOWERS AND THUNDERSTORMS HAVE
DEVELOPED OVER PORTIONS OF THE FORECAST AREA THIS AFTERNOON. PER
RADAR...GREATEST COVERAGE IS CURRENTLY OVER NORTHERN UTAH AND
SOUTHWEST WYOMING NEAR A WEAK BOUNDARY. GUSTY WINDS REMAIN THE
PRIMARY THREAT WITH THESE CELLS THROUGH THIS EVENING THOUGH THERE
HAVE ALSO BEEN A FEW REPORTS OF PEA SIZED HAIL AND BRIEF HEAVY
RAIN. THE WEAKLY DEFINED SYSTEM MOVING INTO SOUTHERN ARIZONA IS
HELPING TO PRODUCE SOME ISOLATED SHOWERS OVER PRIMARILY SOUTHWEST
UTAH...BUT THEY ARE NOT PARTICULARLY IMPRESSIVE AT THIS TIME.
CLOUD COVER AND SLIGHT COOLING OF THE AIRMASS IS KEEPING
TEMPERATURES DOWN A BIT COMPARED TO YESTERDAY AFTERNOON...BUT
MAXES ARE STILL RUNNING AT LEAST 10F ABOVE SEASONAL NORMS.

A BROAD PACIFIC NORTHWEST TROUGH IS PROGGED TO MOVE ONSHORE
TOMORROW. EJECTING WAVE ON THE FRONT END OF THIS SYSTEM SHOULD
BRING ANOTHER FRONTAL BOUNDARY INTO NORTHERN UTAH FRIDAY
AFTERNOON/EVENING.  WITH THE INCREASED MOISTURE AND INSTABILITY
WITH THIS INITIAL BOUNDARY...EXPECTING AN INCREASE IN COVERAGE OF
SHOWERS AND THUNDERSTORMS. TERRAIN WILL BE THE FOCUS AGAIN BUT
INCREASING STEERING FLOW SHOULD ALLOW FOR SOME MORE DRIFT. THE
FRONT IS EXPECTED TO STALL OVER CENTRAL UTAH FRIDAY NIGHT/EARLY
SATURDAY...ACTING AS A FOCUS FOR NOCTURNAL CONVECTION.

EC/GFS INDICATING THAT THE MAIN TROUGH WILL ENTER WESTERN UTAH BY
LATE SATURDAY AFTERNOON. THE ASSOCIATED COLD FRONT IS ON TRACK TO
CROSS THE FORECAST AREA SATURDAY EVENING/EARLY SUNDAY AS THE
CENTER OF THE TROUGH DIVES SOUTH INTO NORTHERN ARIZONA. THE OLD
BOUNDARY THAT WAS STALLED OVER CENTRAL UTAH ALSO LOOKS TO ACT AS A
SECONDARY FOCUS FOR PRECIPITATION AS IT MOVES THROUGH SOUTHERN
UTAH OVERNIGHT SATURDAY. ADDITIONAL INSTABILITY SHOWERS WILL
CONTINUE SUNDAY...DECREASING IN COVERAGE FROM WEST TO EAST SUNDAY
AFTERNOON. PRECIPITATION TYPE SHOULD BE MOUNTAIN SNOW/VALLEY RAIN.
12Z RUNS INDICATE A SLIGHTLY WARMER SYSTEM...WITH 700 MB TEMPS IN
THE -4C TO -6C RANGE...LIMITING THE THREAT OF SNOW IN VALLEY
LOCATIONS.

&&

.LONG TERM (AFTER 00Z MONDAY)...BOTH THE EC AND GFS SHOW SOME 700 MB
MOISTURE AND PRECIP REMAINING OVER THE EASTERN PORTION OF THE CWA
THROUGH SUNDAY EVENING AND INTO MONDAY OVER THE UINTAS AND SOUTHWEST
WYOMING. THE 700 MB WINDS WILL ARE FORECAST TO BE NORTHWEST TO NORTH
AT 20-35 KTS ACROSS THE MOST OF THE CWA SUNDAY EVENING WHICH SHOULD
MAKE FOR SOME BREEZY CONDITIONS WITH POSSIBLY LOCALLY WINDY
CONDITIONS IN THE FAVORABLE DOWNSLOPE REGIONS IN CASTLE COUNTRY AND
IN WASHINGTON COUNTY.

THE SURFACE HIGH BUILDS IN MONDAY WITH A MODEST SURFACE GRADIENT
REMAINING OVER THE SOUTHERN AND EASTERN PORTIONS OF THE CWA.
TEMPERATURES WILL WARM ABOUT 4-6 DEGREES CELSIUS AT 700 MB FROM LATE
SUNDAY TO LATE MONDAY WITH ANOTHER 3-4 DEGREES FROM MONDAY TO
TUESDAY...SO THE WARMING TREND WILL BE RAPID AND CONTINUE INTO
MIDWEEK. WARMEST TEMPERATURES OF THE SEASON EXPECTED WEDNESDAY AND
THURSDAY.

AFTER A SLIGHT CHANCE OF PRECIP OVER THE NORTHERN MOUNTAINS THURSDAY
EVENING AS MODELS STARTING TO HINT AT A TROUGH APPROACHING WITH THE
EC MORE PROGRESSIVE AND WEAKER THAN THE GFS.

&&

.AVIATION....OUTFLOWS FROM NEARBY SHOWERS WILL DICTATE THE WIND
DIRECTION AT THE SLC TERMINAL THROUGH ABOUT 00Z BEFORE THE WINDS ARE
LIKELY TO TAKE ON A SOUTHEAST DIRECTION ONCE AGAIN. THERE IS A 30
PERCENT CHANCE THAT THE WINDS BECOME NORTHWEST FROM 00Z UNTIL 03Z
BEFORE SHIFTING SOUTHERLY.

&&

.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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