Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 261721
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1121 AM MDT FRI SEP 26 2014

.SYNOPSIS...A MILD SOUTHWESTERLY FLOW WILL REMAIN OVER THE AREA
TODAY. A COOL PACIFIC SYSTEM WILL MOVE INLAND TONIGHT AND SLOWLY
CROSS THE GREAT BASIN SATURDAY THROUGH MONDAY.

&&

.DISCUSSION...ACTIVE PERIOD AHEAD AND WILL BE FOCUSING ON THE
NEXT 36 HOURS...THOUGH COOL UNSETTLED CONDITIONS WILL PERSIST
THEREAFTER INTO EARLY NEXT WEEK.

SHORT WAVE ENERGY ROTATING AROUND THE BASE OF THE EASTERN PACIFIC
TROUGH SETTING THE STAGE FOR STRONG SURFACE CYCLONGENESIS OVER
SOUTHERN NEVADA LATER TODAY THROUGH TONIGHT. THE FORECAST AREA
REMAINS WITHIN THE WARM SECTOR OF THIS FOR THE TIME BEING WITH
DEEP LAYER SOUTHWESTERLY FLOW AIDING A MODEST MOISTURE TAP...PWAT
VALUES STEADILY INCREASING NAMELY WEST OF I-15 WITH VALUES NEAR OR
JUST OVER AN INCH PER LATEST SPC MESOANALYSIS AND BLENDED TPW
IMAGERY. CONVECTION WILL BEGIN TO BECOME A THREAT ACROSS THE WEST
THIS AFTERNOON/EVE AS DIURNAL DESTABILIZATION WILL YIELD MLCAPE
VALUES APPROACHING 1000 J/KG...EFFECTIVE SHEAR 30-40 KNOTS AIDING
SOME ORGANIZATION TO CELLS AND DRY BOUNDARY LAYER SUPPORTING A
SLIGHT THREAT OF SEVERE WIND GUSTS. GOING POPS LOOK GOOD IN THE
NEAR TERM AS COVERAGE SHOULD REMAIN SCATTERED OR LESS ACROSS THE
WEST. OUTSIDE OF THIS THREAT...SENSIBLE WEATHER ACROSS THE
FORECAST AREA TODAY WILL REMAIN VERY WARM WITH MAX TEMPS SOME 10
TO 15 DEGREES ABOVE CLIMO.

WITH AFOREMENTIONED CYCLOGENESIS AND ASSOCIATED FRONTOGENESIS
EXPECTED OVER SOUTHERN/EASTERN NEVADA THIS EVE...ENVIRONMENT
ACROSS THE FAR WEST AND ESPECIALLY SOUTHWEST WILL BECOME QUITE
FAVORABLE FOR RAPID CONVECTIVE DEVELOPMENT OVERNIGHT. FURTHER
MOISTENING AND STEEPENING MID LEVEL LAPSE RATES ACROSS THOSE AREAS
LOOK TO YIELD IMPRESSIVE MUCAPE VALUES...WITH KSGU BUFR SUGGESTING
NEAR 1500 J/KG WITH A FAIRLY MEATY PROFILE FOR OUR AREA. NOTED
SHEAR SUPPORTING POTENTIAL FOR ORGANIZATION AND MAINTENANCE TO
CELLS AND LARGE SCALE FORCING AIDING LIFT. CONVERGENT FLOW AT THE
SURFACE AHEAD OF THE INTENSIFYING FRONT SHOULD FOCUS CONVECTION
ALONG A FAIRLY NARROW NORTH/SOUTH ORIENTED BAND WITH FLOW ALOFT
NEARLY PARALLEL TO BOUNDARY AIDING A THREAT OF TRAINING STORMS.
CAN NOT RULE OUT SEVERE STORMS...POSSIBLY SUPERCELLS...ACROSS THE
SOUTHWEST TONIGHT AND THE THREAT OF TRAINING COULD PRODUCE
LOCALIZED FLASH FLOODING. WILL ADDRESS ANY NEED FOR A FLASH FLOOD
WATCH WITH THE AFTERNOON PACKAGE.

UPPER LOW SHOULD PEAK OUT DEVELOPMENT-WISE TOMORROW MORNING...MID
LEVEL FRONTAL BOUNDARY SHIFTING EAST ACROSS THE FORECAST AREA
THROUGH THE DAYTIME HOURS WILL SPREAD MODERATE RAIN WITH EMBEDDED
STORMS...SOME STRONG...ACROSS THE FORECAST AREA. 24 HOUR QPF
TOTALS THROUGH 06Z TOMORROW CONTINUE TO RUN IN THE 1 TO 2 INCH
RANGE OVER MUCH OF THE AREA.

PREVIOUS DISCUSSION FOLLOWS...

A DRY SLOT WILL PUNCH INTO THE AREA BEHIND THE FRONT SO EXPECT
PRECIPITATION TO WIND DOWN ACROSS SOUTHERN UTAH FROM WEST TO EAST
TOMORROW NIGHT. AS THE LOW CONTINUES TO SLOWLY TRACK ACROSS THE
AREA...INSTABILITY SHOWERS WILL CONTINUE ON SUNDAY WITH SOME
LOCALLY ENHANCED ACTIVITY AS VARIOUS EMBEDDED DISTURBANCES ROTATE
AROUND THE LOW CENTER. LINGERING SHOWERS WILL CONTINUE ACROSS THE
NORTH ON MONDAY AS MOISTURE CONTINUES TO WRAP AROUND THE DEPARTING
LOW.

MUCH COOLER TEMPERATURES ARE STILL PROGGED TO ACCOMPANY THIS STORM
SYSTEM. A NOTICEABLE DROP IN TEMPERATURES WILL OCCUR TOMORROW...WITH
MANY AREAS BECOMING 5-10 DEGREES BELOW CLIMO FOR SUNDAY AND MONDAY.
ALL TOLD...THIS IS SHAPING UP TO BE QUITE A SOAKER WITH MODELS
DEPICTING OVER 1 INCH STORM TOTALS ACROSS MANY AREAS...PEAKING
GREATER THAN 2 INCHES IN SOME AREAS. WITH THE ARRIVAL OF COLDER
TEMPERATURES...ACCUMULATING SNOW IS EXPECTED ON THE HIGHER PEAKS.
ALTHOUGH THERE IS STILL SOME SPREAD IN H7 TEMPERATURES BETWEEN THE
VARIOUS MODELS...MOST OF THE SNOW WILL LIKELY OCCUR ABOVE 9KFT
BEGINNING LATE SUNDAY.

ANOTHER STORM SYSTEM IS STILL IN THE PICTURE FOR TUESDAY NIGHT AND
WEDNESDAY AS IT IS FORECAST BY GLOBAL MODELS TO DROP IN FROM THE
NORTHWEST. HOWEVER...THE EC SOLUTION STILL DEPICTS A SLOWER...DEEPER
AND MORE MOIST SYSTEM THAN THE GFS. WILL HAVE TO SEE HOW THIS PANS
OUT...BUT IT CURRENTLY DOES NOT APPEAR TO BE AS COLD OF A SYSTEM AS
MODELS WERE INDICATING LAST NIGHT.


&&

.AVIATION...GUSTY SOUTHERLY WINDS WILL PERSIST AT THE KSLC
TERMINAL THROUGH TODAY. GUSTS OVER 30 MPH ARE EXPECTED TO PERSIST
THROUGH 20Z WITH A 60 PERCENT CHANCE OF LASTING THROUGH 00Z.

&&

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

$$

MERRILL


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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