Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 191616
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1016 AM MDT SAT JUL 19 2014

.SYNOPSIS...IN ASSOCIATION WITH AN UPPER LEVEL DISTURBANCE
LIFTING NORTHEAST ACROSS THE INTERMOUNTAIN REGION...MOISTURE WILL
INCREASE TONIGHT AND SUNDAY. A RIDGE OF HIGH PRESSURE CENTERED
NEAR THE FOUR CORNERS AREA WILL AMPLIFY EARLY NEXT WEEK.


&&

.DISCUSSION...WATER VAPOR IMAGE THIS MORNING SHOWS SUBSIDENCE
DRYING IN NORTHERN UTAH FOLLOWING THE PASSAGE OF A WEAK WAVE TO
THE NORTHEAST...WHICH SHOULD KEEP THE NORTHERN THIRD OF UTAH DRY
THROUGH THE DAY. CONVECTION WILL LIKELY FIRE UP OVER THE HIGHER
TERRAIN SOUTH OF THIS BOUNDARY...AS SUPPORTED BY PW VALUES OF
0.7-0.9 INCHES AND SUFFICIENTLY NEGATIVE GFS LIFTED INDEX VALUES
OVER THE CENTRAL AND SOUTH CENTRAL MOUNTAINS.

A POTENT FEATURE MOVING RAPIDLY NORTHWEST THROUGH SOUTHERN
ARIZONA WILL SEND A SURGE OF MOISTURE INTO THE STATE BEGINNING
THIS EVENING. THIS WAVE SHEARS AS IT NUDGES THE WESTERN UTAH
BORDER BUT STILL DELIVERS THE BEST CHANCE OF MOISTURE DURING
SUNDAY AFTERNOON FOR MUCH OF THE NORTHERN TWO-THIRDS OF THE
STATE...AS SHOWN IN THE NAM12.

AS THIS DISTURBANCE EXITS ON MONDAY...HIGH PRESSURE
BUILDS...SOUTHWEST FLOW BEGINS TO DOMINATE AND A RAPID DRYING
TREND ENSCONCES THE ENTIRE STATE BY TUESDAY. MODELS AGREE ON AN
EAST-WEST ELONGATION OF THE RIDGE AXIS ON WEDNESDAY...ALLOWING A
SHORT-LIVED RETURN OF MOISTURE INTO THE REGION. AFTER MID-WEEK
UTAH QUICKLY BECOMES SANDWICHED BETWEEN THIS RIDGE AND AN UPPER
LEVEL LOW CAREENING TO THE NORTH...BRINGING ZONAL FLOW AND DRIER
AIR STATEWIDE THROUGH THE END OF THE WEEK.

&&

.AVIATION...LIGHT SOUTHEAST WINDS AT THE KSLC TERMINAL WILL SHIFT TO
NORTHWEST AROUND 18Z TODAY. THERE WILL BE HAZY SKIES DUE TO SMOKE
FROM DISTANT FIRES.

&&

.FIRE WEATHER...A DRIER NORTHWEST FLOW WILL REMAIN ACROSS NORTHERN
UTAH THROUGH TODAY AND INTO TONIGHT. RELATIVE HUMIDITY VALUES NEAR
10 PERCENT ARE EXPECTED IN THE NORTHWEST VALLEYS. ENOUGH RESIDUAL
MOISTURE REMAINS IN PLACE OVER CENTRAL AND SOUTHERN AREAS TO
SUPPORT ISOLATED THUNDERSTORMS THIS AFTERNOON AND EVENING...MAINLY
ACROSS THE HIGHER TERRAIN BUT WILL DRIFT SOUTHEAST ACROSS ADJACENT
VALLEYS BY EVENING. A DISTURBANCE MOVING RAPIDLY NORTHWARD FROM
SOUTHERN CALIFORNIA WILL BEGIN TO SPREAD MOISTURE NORTHWARD INTO
SOUTHERN UTAH TONIGHT AND ACROSS CENTRAL AND NORTHERN UTAH SUNDAY.
DUE TO THE TIMING THE SOUTH WILL HAVE THE LOWEST THREAT OF
THUNDERSTORMS BY SUNDAY AFTERNOON AS THE BEST MOISTURE AND DYNAMICS
WILL BE NORTH OF THAT AREA BY THEN. WINDS WILL INCREASE OUT OF THE
SOUTHWEST ACROSS SOUTHERN AND CENTRAL UTAH SUNDAY AFTERNOON BEHIND
THIS DISTURBANCE AND SPEEDS COULD LOCALLY EXCEED CRITICAL VALUES BUT
HUMIDITY VALUES SHOULD REMAIN GENERALLY HIGH ENOUGH TO PREVENT THE
DEVELOPMENT OF  WIDESPREAD CRITICAL FIRE WEATHER CONDITIONS.

THE SOUTHERLY FLOW WILL CONTINUE MONDAY AND TUESDAY WITH BREEZY
CONDITIONS EXPECTED OVER THE WESTERN VALLEYS AND THE AIRMASS WILL
DRY OUT. THIS WILL SEND HUMIDITY VALUES DOWN INTO CRITICAL LEVELS
AND A FIRE WEATHER WATCH REMAINS IN EFFECT FOR THE WESTERN VALLEYS
BOTH DAYS. WINDS ARE EXPECTED TO INCREASE WEDNESDAY BUT AN UPTICK IN
RELATIVE HUMIDITY VALUES MAY KEEP THESE WESTERN ZONES FROM FALLING
BELOW CRITERIA AGAIN WEDNESDAY AFTERNOON. LIGHTER WINDS ARE FORECAST
FOR THE REST OF THE WEEK.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY EVENING
     FOR UTZ478-492-495.

WY...NONE.
&&

$$

PUBLIC...VERZELLA
FIRE WEATHER/AVIATION...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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