Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 201617
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1017 AM MDT SAT SEP 20 2014

.SYNOPSIS...AN UPPER LEVEL LOW PRESSURE SYSTEM ALONG THE SOUTHERN
CALIFORNIA COAST WILL LIFT NORTHEAST INTO THE THEN ACROSS THE
GREAT BASIN SUNDAY THROUGH EARLY MONDAY. HIGH PRESSURE WILL
FOLLOW FOR MID WEEK.

&&

.DISCUSSION...THE UPPER LOW CURRENTLY POSITIONED ALONG THE
SOUTHERN CALIFORNIA COAST WILL BEGIN TO TRACK NORTHEAST THIS
AFTERNOON. THIS FEATURE WILL CONTINUE ON A NORTHEAST INTO THE
WESTERN GREAT BASIN EARLY SUNDAY...REACHING NORTHERN UTAH SUNDAY
EVENING. THE UPPER LOW WILL TAKE A TURN TO THE EAST AS IT EXITS
THE REGION LATE SUNDAY NIGHT/EARLY MONDAY. HEIGHTS WILL BEGIN TO
BUILD BEHIND THE EXITING LOW...WITH A STRONG UPPER RIDGE CENTERED
ACROSS THE EASTERN GREAT BASIN MIDWEEK.

THE STRONGEST CONVECTION ASSOCIATED WITH THE UPPER LOW REMAINS IN
THE NORTHEAST FLANK ACROSS SOUTHERN AND WESTERN NEVADA THIS
MORNING. CONVECTION REMAINS SOMEWHAT MUTED ACROSS SOUTHWEST UTAH
LATE THIS MORNING. CONVECTION WILL PICKUP THROUGH THE AFTERNOON
AS GOOD SURFACE HEATING DEVELOPS AND PWAT VALUES RANGE BETWEEN
/.75/ AND /1.00/ INCHES. DEEP CONVECTION MAY STRUGGLE TO DEVELOP
THIS AFTERNOON AS MID-LEVEL TEMPS REMAIN STATIC AND INHIBIT DEEP
LAYER INSTABILITY.

SHOWERS/THUNDERSTORMS SHOULD INCREASE DRAMATICALLY TONIGHT AS THE
UPPER LOW ADVANCING INTO THE WESTERN GREAT BASIN. THE GREATEST
CONCENTRATION OF CONVECTION SHOULD REMAIN IN THE NORTHEAST FLANK
OF THE LOW...WITH WESTERN UTAH IN LINE FOR SCATTERED SHOWERS AND
STORMS THIS EVENING. NORTHERN UTAH WILL BECOME THE FOCUS FOR
PRECIP LATE TONIGHT/EARLY MONDAY AS THE CENTER OF THE UPPER LOW
MOVES EAST-NORTHEAST THROUGH EXTREME NORTHERN UTAH. MOST PRECIP
SHOULD TAPER OFF DURING THE AFTERNOON...WITH ONE QUICK SHOT OF
ADDITIONAL SHOWERS ALONG A TRAILING SHORTWAVE MONDAY EVENING.

BUILDING HEIGHTS IN THE WAKE OF THE EXITING UPPER LOW WILL
EVENTUALLY FORM A VERY STRONG UPPER RIDGE EXTENDING FORM THE
NORTHERN PLAINS TO THE DESERT SOUTHWEST MIDWEEK. UNSEASONABLY
WARM TEMPS AND BONE DRY CONDITIONS WILL EXISTS THROUGH AT LEAST
THURSDAY...FOLLOWED BY A NEW AND FAIRLY STRONG PACIFIC TROUGH
SCHEDULED TO REACH THE WESTERN GREAT BASIN BY THE END OF THE WEEK.

&&

.FIRE WEATHER...MOISTURE RETURNS NORTH TODAY ACROSS SOUTHERN
UTAH...PROMPTING SCATTERED CONVECTION WHICH MAY BRING LOCALLY HEAVY
RAINFALL IN ADDITION TO CLOUD TO GROUND LIGHTNING. THIS ACTIVITY IS
FORECAST TO SPREAD INTO CENTRAL UTAH TONIGHT AND NORTHERN UTAH
SUNDAY. SUNDAY WILL SEE THE MOST WIDESPREAD CHANCE OF RAINFALL AS A
WEAKENING STORM SYSTEM CROSSES THE EASTERN GREAT BASIN. THIS PATTERN
WILL BRING MORE EXPANSIVE CLOUD COVER...RISING HUMIDITY LEVELS AND
COOLING TEMPERATURES. CONVECTION LINGERS MONDAY ACROSS THE NORTH AND
EAST...DECAYING FOR GOOD MONDAY EVENING.

A WARMING AND DRYING TREND WILL BEGIN MONDAY ACROSS THE SOUTH AND BE
IN PLACE ACROSS THE ENTIRE REGION THROUGH MID WEEK AS A RIDGE OF
HIGH PRESSURE AMPLIFIES OVERHEAD.

THERE REMAINS SIGNIFICANT UNCERTAINTY REGARDING THE TIMING OF A
STRONG COLD FRONT LATE IN THE WEEK. CRITICAL FIRE WEATHER CONDITIONS
WILL BE POSSIBLE AHEAD OF THE COLD FRONT WITH STRONG GUSTY SOUTH
WINDS DEVELOPING...BEFORE CONVECTIVE CHANCES ONCE AGAIN INCREASE
NEXT WEEKEND.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH THE VALID TAF PERIOD
AT THE SLC TERMINAL...THOUGH A CEILING ABOVE 8000 FT CAN BE
ANTICIPATED NEAR THE END OF THE TAF PERIOD WHEN THE CHANCE FOR
SHOWERS AND AN EMBEDDED THUNDERSTORM SIGNIFICANTLY INCREASE SUNDAY
MORNING. A LIGHT SOUTHEASTERLY DRAINAGE WIND WILL SHIFT TO A
NORTHWEST FLOW LAKE BREEZE A BIT EARLIER TODAY...AROUND MIDDAY...DUE
TO A NORTHERLY PRESSURE GRADIENT IN PLACE. A SOUTHEAST DRAINAGE WIND
WILL DEVELOP AGAIN TONIGHT AND SHOULD BE ENHANCED A BIT BY A
DEVELOPING EASTERLY FLOW ALOFT.

&&

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

$$

PUBLIC...CONGER
FIRE WEATHER/AVIATION...ROGOWSKI

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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