Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 051002
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
402 AM MDT WED AUG 5 2015

.SYNOPSIS...A WEAK UPPER LEVEL DISTURBANCE WILL SCRAPE ACROSS THE
NORTHERN GREAT BASIN TODAY...WITH AN ASSOCIATED WEAK COLD FRONT
DROPPING INTO NORTHERN UTAH. A RIDGE OF HIGH PRESSURE WILL BUILD
OVER THE REGION ON THURSDAY. A TROUGH OF LOW PRESSURE OVER
CALIFORNIA WILL LIFT ACROSS THE GREAT BASIN FRIDAY AND SATURDAY.

&&

.SHORT TERM (THROUGH 06Z SUNDAY)...AN UPPER LOW CURRENTLY SPINNING OVER
NORTHERN CALIFORNIA IS FORECAST TO TRANSLATE EAST-NORTHEASTWARD
ACROSS THE NORTHERN GREAT BASIN TODAY...BEFORE PUSHING A RELATIVELY
WEAK COLD FRONT THROUGH NORTHERN UT LATE THIS AFTERNOON THROUGH THIS
EVENING. AHEAD OF THIS FRONT STRENGTHENING SOUTHWESTERLY FLOW SHOULD
YIELD BREEZY CONDITIONS ACROSS MOST WESTERN VALLEYS...WHILE MAX
TEMPERATURES RUN NEAR CLIMO. DYNAMICS ASSOCIATED WITH THE PASSING
TROUGH AND ATTENDANT UPPER JET WILL SUPPORT A GOOD CHANCE OF SHOWERS
AND THUNDERSTORMS LATER THIS AFTERNOON NORTH OF THE SURFACE BOUNDARY
ALONG THE TRAILING 700MB BAROCLINIC ZONE...AND HAVE INCREASED POPS
NORTH OF I-80 ACCORDINGLY. THIS SYSTEM QUICKLY LIFTS OFF TO THE
NORTHEAST THIS EVENING BRINGING A QUICK END TO THE CHANCE OF PRECIP.

MID LEVEL RIDGING IS FORECAST TO BRIEFLY AMPLIFY ACROSS THE REGION
DURING THE DAY THURSDAY. MOISTURE SHOULD BE SUFFICIENT TO SUPPORT
ISOLATED CONVECTION OVER THE HIGHER TERRAIN FROM THE UINTAS
SOUTHWARD INTO CENTRAL AND SOUTHERN UT.

THE MODELS HAVE BEEN QUITE CONSISTENT OVER THE PAST FEW DAYS
ADVECTING MONSOONAL MOISTURE NORTHWARD INTO THE FORECAST AREA LATE
IN THE WEEK...IN ADVANCE OF AN UPPER LOW WHICH IS FORECAST TO BE
SITUATED ALONG THE CA COAST FRIDAY MORNING. THERE HAVE BEEN
DIFFERENCES FROM RUN TO RUN REGARDING JUST HOW ROBUST THIS MOISTURE
SURGE WILL BE...WITH BOTH THE 00Z GFS AND EC SUGGESTING A
SUBSTANTIAL SURGE INTO THE FORECAST AREA LATE THURSDAY NIGHT THROUGH
FRIDAY. GIVEN THE MODEL CONSISTENCY WITH THE OVERALL MOISTENING
TREND HAVE INCREASED POPS BEGINNING LATE THURSDAY ACROSS THE
SOUTH...AND FRIDAY INTO FRIDAY EVENING AREA WIDE. HEAVY RAIN AND
FLASH FLOOD POTENTIAL WILL BE LARGELY DEPENDENT ON ANY CLOUD
COVER AND THE ABILITY OF THE AIR MASS TO DESTABILIZE. ASSUMING
SUFFICIENT DESTABILIZATION...DEEP LAYER SHEAR LOOKS TO BE
SUPPORTIVE FOR ORGANIZED AND POTENTIALLY STRONG CONVECTION.

AS THIS UPPER LOW EJECTS INLAND DRIER AIR IS FORECAST TO QUICKLY
OVERSPREAD THE AREA FROM THE SOUTHWEST...WITH ANY CHANCE FOR
CONVECTION SATURDAY CONFINED TO THE NORTH.


.LONG TERM (AFTER 06Z SUNDAY)...REMNANTS OF UPPER LEVEL LOW SLIDE
EAST ACROSS ROCKIES EARLY IN THE PERIOD.

GFS AND ECMWF IN GOOD AGREEMENT WITH BUILDING RIDGE OF HIGH
PRESSURE OVER THE REGION...WITH RIDGE CENTER JUST EAST OF FOUR
CORNERS AREA MONDAY AND TUESDAY. WITH MAJORITY OF GFS ENSEMBLE
MEMBERS INDICATING SIMILAR SOLUTION...CONFIDENCE IS RATHER HIGH.
PERSISTENT...THOUGH RATHER WEAK...SOUTHERLY MID LEVEL FLOW ON
WESTERN PERIPHERY OF HIGH WILL PUSH MOISTURE NORTH INTO REGION
MONDAY NIGHT AND TUESDAY...WITH PRECIPITABLE WATER VALUES PROGGED
TO INCREASE TO OVER AN INCH. THOUGH DISTINCT LACK OF ANY FORCING
MECHANISM...ENOUGH MOISTURE TO JUSTIFY SLIGHT CHANCE TO CHANCE
WORDING FOR SHOWERS AND THUNDERSTORMS OVER AT LEAST SOUTHEASTERN
HALF OF FORECAST AREA ON TUESDAY.

&&

.AVIATION...SOUTH WINDS WILL INCREASE AT KSLC THROUGH THE MORNING
WITH GUSTS IN EXCESS OF 25 KTS LIKELY AFTER 16Z OR SO. WINDS WILL
LIKELY REMAIN SOUTHERLY THROUGH THE AFTERNOON UNTIL THE ARRIVAL OF A
COLD FRONT AROUND 00Z. VFR WINDS ARE EXPECTED TO PREVAIL THROUGH THE
PERIOD.

&&

.FIRE WEATHER...SOUTHWESTERLY WINDS WILL STRENGTHEN LATE THIS
MORNING INTO THE AFTERNOON HOURS ACROSS MUCH OF THE AREA. ALONG WITH
THIS INCREASE IN WINDS...RH VALUES ARE EXPECTED TO FALL INTO THE
TEENS BY EARLY AFTERNOON. THIS IS IN ADVANCE OF A WEAK COLD FRONT
WHICH WILL CROSS NORTHERN UTAH LATE THIS AFTERNOON THROUGH THIS
EVENING...BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS TO FAR
NORTHERN UTAH. HIGH PRESSURE WILL BRIEFLY STRENGTHEN
THURSDAY...BEFORE MONSOON MOISTURE SURGES NORTHWARD ACROSS THE AREA
LATE THURSDAY NIGHT THROUGH FRIDAY. WETTING RAINS WILL BE LIKELY
ACROSS MUCH OF THE AREA WITH THIS MOISTURE RETURN BEFORE DRIER AIR
SPREADS BACK TO THE REGION FROM THE SOUTHWEST BEGINNING SATURDAY.

&&

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

&&

$$

PUBLIC...BARJENBRUCH/SEAMAN
AVIATION...SEAMAN
FIRE WEATHER...SEAMAN

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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