Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 220848
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
248 AM MDT SAT AUG 22 2015

.SYNOPSIS...A RIDGE OF HIGH PRESSURE WILL BUILD OVER THE REGION
ON SATURDAY...THEN PERSIST INTO EARLY NEXT WEEK. MOISTURE WILL
SPREAD NORTHWARD INTO AREA BY MIDWEEK.

&&

.SHORT TERM (THROUGH 12Z TUESDAY)...
WATER VAPOR LOOP SHOWS A STRONG SHORTWAVE TROUGH CROSSING THE
NORTHERN ROCKIES WITH A FLAT RIDGE OVER THE SOUTHWEST CONUS. AMDAR
400-250MB WIND OBSERVATIONS SHOW A 90-125KT NORTHWESTERLY JET FROM
BRITISH COLUMBIA INTO THE PACIFIC NORTHWEST. GOES/GPS/RAP/00Z SLC
RAOB INDICATE THE PRECIPITABLE WATER VALUE RANGES BETWEEN 0.25"-
0.33" NORTHERN MOUNTAINS...TO 0.75"-1.00" ACROSS CENTRAL AND
SOUTHERN VALLEYS.

LOOKS LIKE THE SMOKE FROM THE CALIFORNIA/PACIFIC NORTHWEST FIRES
WILL REMAIN IN PLACE THROUGH THE WEEKEND.

COLD FRONT WILL SETTLE INTO CENTRAL UTAH TODAY. THE NORTH WILL SEE A
DRY STABLE NORTHWEST FLOW ALOFT WITH TEMPERATURES ABOUT 10F COOLER
THAN YESTERDAY. ISOLATED CONVECTION EXPECTED ACROSS CENTRAL AND
SOUTHERN UTAH AS THE FIRST HINT OF THE NEXT MOISTURE SURGE RESTS
ALONG THE ARIZONA BORDER.

SHORT RANGE ENSEMBLES INDICATE WEAK INSTABILITY BUILDS NORTH ALONG
THE SPINE SUNDAY SO EXPANDED MENTION BACK NORTH INTO THE UINTAS AND
BUMPED POPS INTO SCATTERED BASED ON INCREASING MOISTURE AND NCAR WRF
ENSEMBLE SIMULATED REFLECTIVITY OUTPUT. LOOKS LIKE WE DRY OUT A BIT
MONDAY AS SOUTHWESTERLY FLOW ALOFT DEVELOPS...TAPERING CONVECTIVE
CHANCES BACK DOWN TO ISOLATED IN THE MOUNTAINS.

.LONG TERM (AFTER 12Z TUESDAY)...
IN A TREND THAT STARTED WITH THE 00Z EC LAST NIGHT...GLOBAL
MODELS HAVE CONTINUED TO DELAY THE MONSOONAL SURGE PREVIOUSLY
FORECAST TO BEGIN IN EARNEST TUESDAY. TODAYS 00Z GFS AND 00Z
CANADIAN HAVE SLOWED DOWN MUCH CLOSER TO YESTERDAYS EC SOLUTION.
THE NEW EC HAS REMAINED RELATIVELY CONSISTENT WITH PREVIOUS RUNS.

ALL THAT SAID...IT APPEARS NOW AS IF THE MONSOONAL SURGE WILL BEGIN
ACROSS FAR SOUTHERN UTAH TUESDAY AFTERNOON...REACHING THE REMAINDER
OF SOUTHERN AND CENTRAL UTAH OVERNIGHT TUESDAY INTO WEDNESDAY.

GLOBAL MODELS ARE STILL QUITE VARIABLE WITH THE TIMING OF THE
SHORTWAVE FORECAST TO RIDE UP THE WESTERN SIDE OF THE RIDGE...WITH
SOME MODELS BRINGING THE SHORTWAVE NORTHWARD ALONG THE NEVADA/UTAH
BORDER OVERNIGHT TUESDAY INTO WEDNESDAY MORNING. THIS TIMING WOULD
LIKELY LIMIT THE AREAL COVERAGE OF CONVECTION ACROSS THE STATE AS AT
LEAST PORTIONS OF THE STATE WOULD LIKELY BE SUBSIDENT BEHIND THE
WAVE.

GIVEN THAT MUCH OF THE GLOBAL GUIDANCE HAS SHIFTED TO A SLOWER
DEVELOPMENT OF THE MONSOONAL SURGE...DECREASED POPS ACROSS MUCH OF
THE STATE TUESDAY AFTERNOON. INCREASED POPS A BIT WEDNESDAY
AFTERNOON...BUT STILL KEPT POPS FAIRLY LOW GIVEN THE AMOUNT OF DEEP
MOISTURE DUE TO THE LACK OF CONSISTENCY WITH THE TIMING OF THE
SHORTWAVE.

BY THURSDAY...THE UPPER LEVEL RIDGE IS FORECAST TO BUILD BACK INTO
THE AREA...EFFECTIVELY TYING ANY CONVECTION TO MAINLY THE HIGHER
TERRAIN BY THURSDAY AFTERNOON.

&&

.AVIATION...LIGHT AND VARIABLE WINDS ARE EXPECTED TO BECOME
SOUTHERLY BETWEEN 09-12Z AT THE SLC TERMINAL. EXPECT A RELATIVELY
EARLY SWITCH TO A NORTHWEST WIND GIVEN THE GRADIENT...SOMETIME
BETWEEN 15-17Z. OTHERWISE...SMOKE/HAZE ALOFT WILL CONTINUE ACROSS
MUCH OF NORTHERN UTAH TODAY.

&&

.FIRE WEATHER...HUMIDITY VALUES HAVE CREPT HIGHER ACROSS SOUTHERN
UTAH AS A RIDGE OF HIGH PRESSURE BEGINS TO BUILD IN FROM THE SOUTH.
A COLD FRONT THAT MOVED THROUGH NORTHERN UTAH OVERNIGHT WILL SETTLE
ACROSS CENTRAL UTAH TODAY. THIS WILL RESULT IN A 10F DEGREE DROP
ACROSS THE NORTH WITH A SLIGHT INCREASE IN HUMIDITY.

CONVECTION TODAY SHOULD BE ISOLATED AND MAINLY ACROSS THE HIGHER
TERRAIN OF CENTRAL AND SOUTHERN UTAH. WITH MOISTURE SPREADING NORTH
SUNDAY...EXPECTING TO SEE SCATTERED CONVECTION ALONG THE SPINE NORTH
INTO THE UINTA MOUNTAINS.

A PATTERN CHANGE IS IN STORE FOR NEXT WEEK...WITH THE RIDGE OF HIGH
PRESSURE TAKING HOLD OF THE REGION. THIS MONSOONAL PATTERN WILL
SUPPORT AN INCREASE IN CLOUD COVER...CAPPING TEMPERATURES...RISING
HUMIDITY...AND AN INCREASE IN CONVECTIVE COVERAGE.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...RED FLAG WARNING UNTIL 8 PM MDT SATURDAY FOR WYZ277.

&&

$$

SHORT TERM/FIRE WEATHER...ROGOWSKI
LONG TERM/AVIATION...KRUSE

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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