Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 172236
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
436 PM MDT WED SEP 17 2014

.SYNOPSIS...HIGH PRESSURE ALOFT OVER UTAH WILL SHIFT EAST OF THE
STATE TONIGHT. MOISTURE WILL INCREASE AHEAD OF A PACIFIC TROUGH
WHICH WILL SETTLE INTO THE GREAT BASIN LATE IN THE WEEK.



&&

.DISCUSSION...A RIDGE REMAINS OVER THE INTERMOUNTAIN WEST THIS
AFTERNOON...HELPING TO PRODUCE VERY WARM MAXIMUM TEMPERATURES. FOR
EXAMPLE...THE SALT LAKE CITY INTERNATIONAL AIRPORT HAS HIT 94
DEGREES AS OF 22Z...BREAKING THE PREVIOUS RECORD OF 93 SET IN
1937. ENOUGH MOISTURE HAS REMAINED UNDER THIS RIDGE TO FUEL
DIURNAL CONVECTIVE ACTIVITY...PRIMARILY INITIATING OFF THE HIGHER
TERRAIN. AS EXPECTED...ONE EXCEPTION TO THIS IS ALONG THE
UTAH/ARIZONA BORDER...WHERE STRONGER STORMS HAVE BEEN ABLE TO
DEVELOP ON THE NORTHERN EDGE OF THE TROPICAL MOISTURE OVER
ARIZONA. THESE STORMS WILL CONTINUE INTO THE EVENING...BEFORE
POTENTIALLY DISSIPATING DURING THE OVERNIGHT HOURS.

MOISTURE IS STILL ON TRACK TO MOVE NORTHWARD INTO MUCH OF THE
STATE OVERNIGHT...WHICH SHOULD HELP TO FUEL INCREASED SHOWERS AND
THUNDERSTORMS ON THURSDAY. THE BEST COVERAGE IS EXPECTED TO BE
ACROSS NORTHERN UTAH...WHERE A PACIFIC TROUGH SHOULD PROVIDE GOOD
FORCING THROUGH THURSDAY NIGHT. SOME OF THESE STORMS COULD
POTENTIALLY BECOME SEVERE...WITH 0-6 KM BULK SHEAR FORECAST TO
REACH 30-40 KNOTS OVER NORTHWEST UTAH BY 00Z FRIDAY. THAT
SAID...WAS UNABLE TO RAISE POPS MUCH MORE FOR THURSDAY AFTERNOON
OR THURSDAY NIGHT...AS RECENT GFS AND ECMWF RUNS HAVE PRODUCED
LESS QPF AND A SOMEWHAT LESS ORGANIZED BAROCLINIC ZONE MOVING
THROUGH THE NORTHERN CWA.

SHOWERS COULD CONTINUE INTO FRIDAY...ESPECIALLY IN THE
MOUNTAINS...BUT SYNOPTIC SCALE FORCING DECREASES CONSIDERABLY
THROUGH THE DAY...AS THE SOUTHERN BRANCH OF THE TROUGH CUTS OFF
AND MOVES OVER CALIFORNIA...AND THE NORTHERN BRANCH SLIDES OFF
INTO THE DAKOTAS. INCREASED NORTHWESTERLY FLOW FROM THAT NORTHERN
BRANCH SHOULD HELP DRY OUT THE CWA THROUGH FRIDAY AND FRIDAY
NIGHT...WITH PRECIPITABLE WATER VALUES FORECAST TO DROP FROM ONE
INCH TO HALF AN INCH IN A LITTLE MORE THAN 24 HOURS.

HOWEVER...THIS DRYING WILL BE FAIRLY SHORT-LIVED. MOST OF THE CWA
WILL SEE A SUNNY DAY ON SATURDAY...BUT SOUTHERLY FLOW AHEAD OF THE
CLOSED LOW OVER CALIFORNIA WILL PUSH MOISTURE BACK INTO SOUTHERN
UTAH SATURDAY AFTERNOON OR SATURDAY EVENING. THAT LOW IS THEN
PROGGED TO PUSH NORTHEASTWARD...DIRECTLY THROUGH UTAH...SUNDAY AND
MONDAY. HAVE CONTINUED TO INCREASE POPS ACROSS THE AREA FOR THIS
TIMEFRAME...AS CONDITIONS ARE LOOKING MORE AND MORE FAVORABLE FOR
RAIN ACROSS ALMOST THE ENTIRE CWA. BEYOND MONDAY...THE LOW EXITS
THE AREA...AND A RIDGE REBUILDS OVER THE REGION. WITH DECENT MODEL
AGREEMENT IN THIS SOLUTION...HAVE INCLUDED THIS DRYING AND WARMING
TREND IN THE FORECAST FOR TUESDAY AND WEDNESDAY.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED THROUGH THE OVERNIGHT
PERIOD AT THE KSLC TERMINAL. LIGHT NORTHWEST WINDS THIS AFTERNOON
WILL SWITCH TO THE SOUTHEAST BETWEEN 0200 UTC AND 0400 UTC. SOUTH
WINDS ARE EXPECTED TO INCREASE AFTER 1200 UTC.


&&

.FIRE WEATHER...MOISTURE HAS SURGED INTO SOUTHERN UTAH THIS AFTERNOON
TRIGGERING THUNDERSTORMS ACROSS THE HIGH TERRAIN. THIS MOISTURE WILL
CONTINUE TO INFILTRATE THE FORECAST AREA THURSDAY INTO FRIDAY
...INTERACTING WITH AN APPROACHING PACIFIC TROUGH TO ENHANCE THE
LIKELIHOOD AND COVERAGE OF AFTERNOON THUNDERSTORMS EACH
DAY...PARTICULARLY ACROSS NORTHERN AND CENTRAL UTAH. SATURDAY
USHERS IN A BRIEF DRYING TREND QUICKLY FOLLOWED BY A LOW PRESSURE
SYSTEM WHICH WILL INCREASE WETTING RAIN POTENTIAL AGAIN SUNDAY AND
MONDAY.

&&

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

$$

PUBLIC...SCHOENING
FIRE WEATHER...VERZELLA
AVIATION...GRAHAM

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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