Flash Flood Warning 15, NWS Salt Lake City, UT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
250 PM MDT THU JUL 15 2004

.SYNOPSIS...AN AIRMASS WITH DEEP MOISTURE AND WEAK FLOW ALOFT WILL
REMAIN OVER THE AREA INTO THE WEEKEND.

&&

.DISCUSSION...CONVECTION DEVELOPED EARLIER TODAY OVER SW UTAH IN
AREAS THAT CLEARED. SO FAR MOST STORMS HAVE BEEN INTENSE BUT SHORT
LIVED WITH RESULTING HIGH PRECIPITATION RATES...BUT BASIN AVERAGE
ACCUMULATIONS ARE GENERALLY LESS THAN 2 INCHES SO FAR. LARGE RAIN
COOLED AREA NOW COVERS MUCH OF SOUTHERN MOUNTAINS FROM BCE NORTHWARD
WITH MORE CELLS OVER HIGHER TERRAIN OF NW AZ AND S NV. MUCH OF KANE
AND WASHINGTON COUNTY NOW SURROUNDED...OUTFLOWS WILL LIKELY CONVERGE
AND STORMS WILL DEVELOP IN THIS AREA LATER THIS AFTERNOON/EARLY THIS
EVENING. CELL MOVEMENT HAS BEEN VERY SLOW...SO STILL A THREAT OF
FLASH FLOODING THROUGH THIS EVENING.

N UTAH QUITE A BIT COOLER TODAY THAN AT SAME TIME YESTERDAY DUE TO
EXTENSIVE RAIN COOLED AIR FROM YESTERDAY EVENINGS CONVECTION.  THIS
AND CLOUD COVER HAS MINIMIZED ACTIVITY SO FAR TODAY.

ELSEWHERE CONVECTION FOCUSED MAINLY ON TERRAIN AND ANOTHER AREA
ASSOCIATED WITH SHORT WAVE IN NE NV...EXPECT CONVECTION OVER THE
NORTHERN AREAS THIS EVENING AS OUTFLOWS FROM THIS ACTIVITY CONVERGE.

FRIDAY...GFS/ETA BOTH SHOW 500 MB ANTICYCLONE OVER THE NORTH WHICH
MAY SUPPRESS ACTIVITY OVER THE NORTH AND AT THE SAME TIME RESULT IN
A WEAK FLOW DEFORMATION ZONE OVER THE SOUTH. SO EXPECT ANOTHER
ACTIVE DAY...BUT MAINLY SOUTH.

SATURDAY...GFS DRIES OUT THE SOUTH SOME AND BRINGS A SHORT WAVE
NORTHWARD INTO NORTHERN PORTION OF FORECAST AREA...ETA DOES NOT SHOW
SAME SHORT WAVE...SO CONFIDENCE NOT TOO HIGH.

FROM SUNDAY ONWARD DAILY ACTIVITY WILL DEPEND ON LOCATION OF THE
UPPER HIGH THAT STARTS SHIFTING AROUND FROM DAY TO DAY IN THE MODELS
WITH LITTLE CONFIDENCE IN EXACT DETAILS...SO HAVE TRENDED FORECASTS
BACK TOWARDS SEASONAL CONVECTIVE ACTIVITY LEVELS ALTHOUGH AM
SKEPTICAL THAT MODELS MAY BE A BIT TOO QUICK TO DRY AIRMASS GIVEN
THE LIGHT FLOW WE WILL SEE BENEATH THE RIDGE.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...

UT...FLASH FLOOD WATCH TODAY AND THIS EVENING FROM I-70 SOUTH AND
ALL OF ZONE 17
WY...NONE.
ID...NONE.

&&

DUNN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
650 AM MDT THU JUL 15 2004

UTZ012>014-016>021-161300-
CASTLE COUNTRY-CENTRAL AND SOUTHWEST MOUNTAINS-GLEN CANYON
RECREATION AREA/LAKE POWELL-HENRY MOUNTAINS-SAN RAFAEL
SWELL-SANPETE/SEVIER VALLEYS-SOUTH CENTRAL UTAH-SOUTHWEST
UTAH-UTAHS DIXIE AND ZION NATIONAL PARK-
650 AM MDT THU JUL 15 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE SOUTHERN THIRD OF UTAH.

.DAY ONE... TODAY

SCATTERED SLOW MOVING THUNDERSTORMS WILL DEVELOP AGAIN TODAY.
LOCALLY HEAVY RAINFALLS ARE POSSIBLE....ESPECIALLY OVER THE
MOUNTAINS AND NEAR THE ARIZONA BORDER.  A FLASH FLOOD WATCH IS IN
EFFECT FOR PORTION OF SOUTHERN UTAH BEGINNING THIS AFTERNOON...
AND CONTINUING THROUGH 800 PM THIS EVENING.  SEE THE LATEST
FLOOD WATCH (SLCFFASLC) FOR DETAILS ON THIS WATCH.

.DAYS TWO THROUGH SEVEN... FRIDAY THROUGH WEDNESDAY

SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE
WEEKEND. SOME OF THESE STORMS WILL PRODUCE LOCALLY HEAVY RAINS
...WITH THE POTENTIAL FOR FLASH FLOODING THROUGH THE WEEKEND.

IDZ024-025-UTZ001>011-015-WYZ021-161300-
CACHE VALLEY/IDAHO PORTION-CACHE VALLEY/UTAH PORTION-GREAT SALT LAKE
DESERT AND MOUNTAINS-NORTHERN WASATCH FRONT-SALT LAKE AND TOOELE
VALLEYS-SOUTHERN WASATCH FRONT-SOUTHWEST WYOMING-WASATCH MOUNTAIN
VALLEYS-WASATCH MOUNTAINS I-80 NORTH-WASATCH MOUNTAINS SOUTH OF I-80-
WASATCH MOUNTAINS/IDAHO PORTION-WASATCH PLATEAU/BOOK CLIFFS-
WEST CENTRAL UTAH-WESTERN UINTA BASIN-WESTERN UINTA MOUNTAINS-
650 AM MDT THU JUL 15 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE NORTHERN TWO THIRDS.
OF UTAH...SOUTHEAST IDAHO AND SOUTHWEST WYOMING.

.DAY ONE... TODAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN... FRIDAY THROUGH WEDNESDAY

SHOWESR AND THUNDERSTORMS WILL CONTINUE INTO AND THROUGH THE
WEEKEND. THESE SHOWERS AND STORMS MAY PRODUCE LOCALLY HEAVY RAIN...
ESPECIALLY OVER NORTHWEST UTAH.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURE.