Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 272203
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
403 PM MDT SUN JUL 27 2014

.SYNOPSIS...MONSOONAL MOISTURE ACROSS SOUTHERN AND CENTRAL UTAH
WILL SLOWLY WORK ITS WAY NORTHWARD THROUGH MONDAY...AND REMAIN
IN PLACE THROUGH MIDWEEK. AN UPPER LEVEL LOW PRESSURE WILL TRACK
NORTH ACROSS UTAH MONDAY THROUGH TUESDAY.

&&

.DISCUSSION...AN UPPER LEVEL RIDGE AXIS CONTINUES TO SHIFT NORTH
AND EAST AT THIS TIME...WITH PLACEMENT FROM WEST CENTRAL COLORADO
TO NORTHWEST UTAH. WIDELY SCATTERED CONVECTION HAS FORMED THIS
AFTERNOON ALONG AND SOUTHWEST OF THIS AXIS...WITH ACTIVITY ACROSS
CENTRAL UTAH AIDED BY A WEAK MID LEVEL WAVE THAT CONTINUES TO
DISSIPATE. NORTHEAST OF THIS ENVIRONMENT REMAINS DRIER AND MORE
SUPPRESSED. HRRR SUGGESTS CONVECTION CURRENTLY DEVELOPING OVER
NORTHERN AND EASTERN NEVADA WILL HOLD TOGETHER AT LEAST IN SOME
MANNER THIS EVE/OVERNIGHT...TRACKING INTO SOUTHERN AND CENTRAL
UTAH OVERNIGHT. RAISED POPS ABOUT 15 PERCENT ACROSS THE
SOUTHERN/CENTRAL MOUNTAINS TONIGHT INTO TOMORROW MORNING AS RAP13
IMPLIES SIMILAR AND IT APPEARS YET ANOTHER RETURN FLOW WAVE MAY BE
DRIVING THIS PER WATER VAPOR. ELSEWHERE SLIGHT CHANCE POPS EXIST
SOUTH AND WEST OF THE AXIS.

GOES DERIVED PWAT AND SPC MESOANALYSIS SHOWING A NORTHWARD SURGE
OF DEEPER MOISTURE FOCUSED ACROSS WESTERN UTAH. NAM12/GFS CONTINUE
THIS TREND OVER THE NEXT 24 HOURS AND CONTINUE TO INDICATE PWATS
OF 1 INCH OR GREATER OVER MOST ALL OF THE CWA BY THIS TIME
TOMORROW.

SHORT WAVE CIRCULATION NOTED IN VISIBLE SATELLITE OVER
SOCAL/AZ BORDER THE PRIMARY FEATURE TO WATCH THROUGH NOW THROUGH
WEDNESDAY. FEEL GLOBAL GUIDANCE HAS THE BEST GRASP ON ITS
EVOLUTION THROUGH THAT TIME...TRACKING INTO CENTRAL NEVADA
RETAINING A CLOSED CIRCULATION BENEATH THE RIDGE AS IT AMPLIFIES
NORTH INTO CANADA. STREAMLINES INDICATE A FAIRLY SUBSTANTIAL
DEFORMATION AXIS ASSOCIATED WITH THIS LIFTING NORTHEAST THROUGH
THE AREA BEGINNING TOMORROW. INTERACTION OF THIS AXIS W/DEEP
MOISTURE IN PLACE WILL BRING A FAIRLY HIGH LIKELIHOOD OF SHOWERS
AND STORMS TO ALL AREAS...WITH LOCALLY HEAVY RAIN POTENTIAL MOVING
INTO THE SOUTHWEST TOMORROW AND CENTRAL/NORTHERN UTAH TUESDAY.

GLOBAL GUIDANCE ALSO SUGGESTS ANOTHER CIRCULATION WILL SPIN UP
OVER NORTHERN UTAH/SOUTHERN IDAHO TUESDAY NIGHT/WEDNESDAY WITHIN
SAID DEFORMATION. LEFT HIGH CHANCE POPS ACROSS THE FAR NORTH TO
NORTHEAST DUE TO THIS...BUT THE SOUTHERN TW0-THIRDS OF THE STATE
APPEAR TO BE QUITE SUPPRESSED IN WAKE OF PASSAGE OF THIS
DEFORMATION AXIS...WITH A SLIGHTLY DRIER AIRMASS.

MADE SIGNIFICANT CHANGES TO MAX TEMPS TUESDAY AND
WEDNESDAY...SHYING AWAY FROM BIAS CORRECTED GUIDANCE. FAIRLY
WIDESPREAD CONVECTION/PRECIP AND H7 TEMPS LOWERING TO NEAR 10C
MAY MAKE IT HARD TO EVEN REACH 80 DEGREES ALONG THE WASATCH FRONT
TUESDAY WITH ONLY A FAIR REBOUND WEDNESDAY. BC GUIDANCE EASILY 10
DEGREES WARMER DUE TO CLIMO INFLUENCE.

THEREAFTER RIDGE POSITIONING WILL SHIFT SLIGHTLY WEST WITH CENTER
OF CIRCULATION OVER CENTRAL ARIZONA. THIS ALLOWING A SOMEWHAT
MOIST WEST TO SOUTHWESTERLY FLOW ALOFT TO PERSIST THROUGH THE
REMAINDER OF THE WEEK. SENSIBLE WEATHER LOOKS PER NORM FOR THIS
TIME OF THE YEAR...WITH DAILY AIRMASS TYPE SHOWERS/STORMS FOCUSED
OVER THE HIGHER TERRAIN AND A GRADUAL WARMING TREND OF TEMPS AFTER
THE MIDWEEK COOL DOWN.

OF NOTE IN THE LONG TERM IS ANOTHER INVERTED TROUGH WITHIN THE
RETURN FLOW NEXT WEEKEND. ECMWF WAS THE FIRST TO INDICATE THIS A
FEW RUNS BACK...WITH 12Z GFS LATCHING ONTO THIS TO SOME DEGREE
THOUGH PRIOR RUNS HAD NOT. GRIDS TRENDING TO THE ECMWF DUE TO ITS
RUN TO RUN CONSISTENCY.

&&

.AVIATION...NORTH TO NORTHWEST WINDS WILL CONTINUE AT THE SLC
TERMINAL BEFORE SWITCHING BACK TO THE SOUTH BETWEEN 03-04Z. THERE IS
A 20 PERCENT CHANCE THAT THUNDERSTORMS IN THE VICINITY OF THE
TERMINAL THROUGH 02Z. ANY THUNDERSTORMS WILL PRODUCE GUSTY AND
ERRATIC WINDS.

&&

.FIRE WEATHER...HUMIDITY HAS COME UP ACROSS ALL BUT THE FAR NORTHERN
PORTIONS OF THE DISTRICT TODAY. HUMIDITY WILL KEEP RISING OVER THE
ENTIRE AREA TONIGHT THROUGH MONDAY AND REMAIN ELEVATED TUESDAY. THIS
WILL KEEP SHOWERS AND THUNDERSTORMS ACTIVE ACROSS THE REGION INTO
TUESDAY WITH A GOOD CHANCE OF WETTING RAINS WITH ANY STORMS. A
REDUCTION IN SHOWER AND THUNDERSTORM COVERAGE IS EXPECTED OVER THE
SOUTH TUESDAY AFTERNOON AND ACROSS PRETTY MUCH THE ENTIRE DISTRICT
WEDNESDAY. HUMIDITY WILL ALSO START TO LOWER AGAIN WEDNESDAY BUT
SUFFICIENT MOISTURE WILL REMAIN ACROSS THE REGION FOR AFTERNOON AND
EVENING MOUNTAIN THUNDERSTORMS EACH DAY THROUGH THE END OF THE
WEEK.

&&

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

$$

MERRILL/KRUSE/WILENSKY


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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