Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 281021
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
421 AM MDT MON JUL 28 2014

.SYNOPSIS...INCREASING MONSOONAL MOISTURE WILL SPAWN SHOWER AND
THUNDERSTORM ACTIVITY ACROSS MUCH OF UTAH THROUGH THIS EVENING.
MOISTURE WILL REMAIN IN PLACE THROUGH MIDWEEK...WITH A GRADUAL
DRYING TREND TO FOLLOW AS HIGH PRESSURE ALOFT STRENGTHENS ACROSS
THE REGION LATE IN THE WEEK.

&&

.DISCUSSION...THE UPPER RIDGE AXIS EXTENDING FROM THE SOUTHERN
ROCKIES NORTH-NORTHWEST INTO WESTERN MONTANA THIS MORNING WILL
GAIN A MORE NORTH-TO-SOUTH ORIENTATION AS THE RIDGE STRENGTHENS
BEGINNING MIDWEEK. FOR TODAY A FAIRLY MOIST AIRMASS AS DEFINED BY
THE 1.00+ INCH PWAT VALUES COVERS MUCH OF SOUTHERN AND WESTERN
UTAH. WHAT APPEARS IN WATER VAPOR IMAGERY TO BE A COUPLE OF WEAK
EASTERLY WAVES OVER ARIZONA WILL LIFT NORTH ALONG THE WEST SIDE
OF THE RIDGE AXIS. THESE FEATURE WILL IMPACT SOUTHWEST AND CENTRAL
UTAH THROUGH EARLY THIS EVENING. THE SLOW-MOVING CONVECTION
GENERATED FROM THIS DYNAMIC LIFT WILL PRODUCE SOME INTENSE HEAVY
RAIN ACROSS THE SOUTH THIS AFTERNOON...THEN INTO CENTRAL UTAH
LATE AFTERNOON AND EVENING. MUCH OF THIS CONVECTION WILL CROSS
FLASH FLOOD PRONE AREAS. HAVE ISSUED A FLASH FLOOD WATCH TO
ADDRESS THE FLOOD POTENTIAL FOR MUCH OF SOUTHERN AND CENTRAL UTAH
FOR THIS AFTERNOON THROUGH MID-EVENING.

LOOKING AT A SIGNIFICANT INCREASE IN CONVECTION ACROSS WEST-
CENTRAL THROUGH NORTHWEST UTAH AS THESE ABOVE MENTIONED DYNAMIC
FEATURES CROSS THE REGION LATER IN THE AFTERNOON AND ON THROUGH
THE OVERNIGHT HOURS. SIMILAR...THOUGH MORE ISOLATED HEAVY RAIN
EVENTS ARE POSSIBLE TONIGHT. WILL HAVE TO WATCH THE OLD BURN
SCARS ACROSS THE NORTH WITH AN EYE ON THE POSSIBILITY OF INTENSE
RAINFALL CREATING DEBRIS FLOWS/FLOODING AT THOSE LOCATIONS.

MOISTURE WILL REMAIN IN PLACE TUESDAY...WITH THE FOCUS MOVING UP
NORTH WHERE THE BEST DYNAMIC SUPPORT FOR CONVECTION WILL EXIST.
SOUTHERN UTAH SHOULD EXPERIENCE A SIGNIFICANT DECREASE IN
CONVECTION...THOUGH ISOLATED HEAVY RAIN EVENTS MAY STILL FORM DUE
TO WEAK MEAN LAYER WINDS AND STILL IMPRESSIVE PWAT VALUES.

A DRYING/WARMING TREND SHOULD DEVELOP MIDWEEK AS THE UPPER RIDGE
AXIS STRENGTHENS ACROSS UTAH. POCKETS OF MOISTURE WILL LIKELY CLIP
THE NORTHWEST PORTION OF UTAH AS THEY ROTATE AROUND THE UPPER
RIDGE LATE IN THE WEEK. WILL CONCENTRATE A LOW-END THREAT FOR
SHOWERS/STORMS ACROSS THE NORTHERN ZONE SLATE IN THE WEEK.

NOT LOOKING AT ANY SUBSTANTIAL BREAKDOWN OF THE UPPER RIDGE OVER
THE REGION THROUGH THE UPCOMING WEEKEND. CONVECTION THAT DOES FIND
A WAY TO DEVELOP WILL BE CONFINED TO THE HIGHER TERRAIN WITH
ISOLATED COVERAGE EXPECTED. BOTH THE ECMWF AND GFS ADVERTISE A
SLOW-MOVING SHORTWAVE LIFTING NORTH THROUGH NEVADA LATE IN THE
WEEKEND. THIS FEATURE WILL LIKELY DRAW ADDITIONAL MOISTURE INTO
SOUTHWEST UTAH SUNDAY...GENERATING A LIGHTLY GREATER CHANCE OF
SHOWERS/THUNDERSTORMS ACROSS THAT PORTION OF THE STATE.

&&

.FIRE WEATHER...MONSOON MOISTURE CONTINUES TO STREAM NORTHWARD
ACROSS ALL FIRE DISTRICTS. HUMIDITIES WILL KEEP RISING OVER THE
ENTIRE AREA TODAY AND REMAIN ELEVATED TUESDAY. THIS WILL MAINTAIN
SHOWERS AND THUNDERSTORMS ACTIVE ACROSS THE REGION INTO TUESDAY
WITH A GOOD CHANCE OF WETTING RAINS. A REDUCTION IN SHOWER AND
THUNDERSTORM COVERAGE IS EXPECTED OVER THE SOUTH TUESDAY AFTERNOON
AS THE AIRMASS BEGINS TO DRY. AS THE RIDGE AXIS SETTLES OVER THE
DISTRICT WEDNESDAY...THE ENTIRE DISTRICT WILL BECOME MUCH DRIER
WITH AN ABATEMENT OF THE MAJORITY OF CONVECTIVE ACTIVITY. ENOUGH
MOISTURE WILL REMAIN ACROSS THE REGION FOR AFTERNOON AND EVENING
MOUNTAIN THUNDERSTORMS EACH DAY THROUGH THE END OF THE WEEK.

&&

.AVIATION...NORTH WINDS WILL CONTINUE AT THE SLC TERMINAL FOR A FEW
HOURS. THERE IS A 30 PERCENT CHANCE THAT WINDS REMAIN NORTH LONGER
BEFORE SWITCHING BACK TO THE SOUTHEAST. NORTHWEST WINDS WILL RETURN
BETWEEN 18-19Z. THERE IS A 20 PERCENT CHANCE OF THUNDERSTORMS IN THE
VICINITY OF THE TERMINAL AFTER 18Z THROUGH 02Z. ANY THUNDERSTORMS
COULD PRODUCE GUSTY AND ERRATIC WINDS.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...FLASH FLOOD WATCH FROM NOON MDT TODAY THROUGH THIS EVENING FOR
     UTZ016-019>021-517-518.

WY...NONE.
&&

$$

PUBLIC...CONGER
AVIATION/FIRE WEATHER...YOUNG

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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