Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 190949
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
349 AM MDT TUE MAY 19 2015

.SYNOPSIS...A STORM SYSTEM WILL CROSS UTAH TODAY. THE NEXT STORM
SYSTEM WILL ARRIVE LATE IN THE WEEK AND IMPACT MUCH OF UTAH
THROUGH THE HOLIDAY WEEKEND.

&&

.SHORT TERM (THROUGH 00Z FRIDAY)...
WATER VAPOR LOOP SHOWS AN EXPANSIVE CLOSED LOW ENTERING WEST
CENTRAL UTAH. AMDAR 400-250MB WIND OBSERVATIONS SHOW A 75-125KT
CYCLONIC JET FROM SOUTHERN CALIFORNIA INTO THE SOUTHERN ROCKIES.
GOES/GPS/RAP/00Z SLC RAOB INDICATE THE PRECIPITABLE WATER VALUE
RANGES BETWEEN 0.25"- 0.50" MOUNTAINS...TO 0.50"-0.75" ACROSS THE
VALLEYS.

TODAY WILL BE A TRANSITION DAY. IT WILL REMAIN QUITE ACTIVE ACROSS
THE NORTH...WITH SOME DRYING ACROSS THE SOUTH.

MAIN FEATURE WILL BE MID LEVEL WARM ADVECTION WRAP-AROUND SUPPORTING
WIDESPREAD SHOWERS ACROSS THE NORTH...MOST FAVORED ALONG THE IDAHO
BORDER AND NORTHWARD. HAVE RAISED POPS WHICH IS SUPPORTED BY RADAR
TRENDS AND HRRR-3KM GUIDANCE. SHORT RANGE ENSEMBLES INDICATE PLENTY
OF INSTABILITY TO POP CONVECTION ACROSS CENTRAL AND SOUTHERN UTAH AS
THE AFTERNOON PROGRESSES. SNOW LEVELS SHOULD BE AROUND 8KFT.
CONVECTION THINS OUT TONIGHT ACROSS THE FAR NORTH AS THE MID LEVEL
WARM ADVECTION WANES.

DEWPOINTS HAVE RISEN TOWARD 50F ACROSS THE NORTH. RAP BUFKIT
FORECAST PROFILES SUGGEST WITH LOWERING OF LCL LEVEL...WARM CLOUD
LAYER IS UP TO 2-4KFT...SUPPORTING AN INCREASE IN RAIN RATES.

WEDNESDAY WILL BE IN BETWEEN SYSTEMS UNDER A SHORTWAVE RIDGE. WITH
PLENTY OF DIURNAL INSTABILITY DUE TO RESIDUAL MOISTURE...HAVE
INDICATED A HIGH END SCATTERED COVERAGE OF AFTERNOON AND EVENING
SHOWERS AND STORMS ALONG AND EAST OF THE WASTACH DUE TO TERRAIN
CIRCULATIONS. THESE THIN LATE WEDNESDAY NIGHT INTO THURSDAY
MORNING...ONLY TO REDEVELOP THURSDAY. EXPECTING GREATER COVERAGE
ESPECIALLY ACROSS THE SOUTHERN ZONES THURSDAY DUE TO ARRIVAL OF
DIFFLUENCE ALOFT AND EXIT REGION OF THE UPPER LEVEL JET ASSOCIATED
WITH THE NEXT STORM SYSTEM.

.LONG TERM (AFTER 00Z FRIDAY)...
THE NEXT CLOSED UPPER LOW WILL BEGIN MOVING INTO SRN CA THU NIGHT
THEN MOVES ENE INTO NWRN AZ BY FRI EVE THEN NEWD TO EITHER NERN UT
OR NWRN CO BY LATE SAT DEPENDING ON WHICH GUIDANCE IS FOLLOWED.
THIS WILL BRING AN INCREASING CHANCE OF SHOWERS TO THE CWA THRU
FRI NIGHT WITH MORE STRATIFORM WRAP AROUND PRECIP POSSIBLE OVER
THE WESTERN CWA ON SAT. HAVE NUDGED POPS UPWARD A LITTLE MORE FRI
THRU SAT BUT STILL ONLY HAVE SCATTERED COVERAGE IN THE VALLEYS.
THIS MAY NEED TO CHANGE AS WE GET CLOSER TO THE END OF THE WEEK.

THE EC REMAINS CONSISTENT WITH ITS EARLIER RUNS DROPPING YET ANOTHER
CLOSED LOW INTO THE NRN GREAT BASIN ON SUN THAT THEN DRIFTS SLOWLY
EAST ACROSS NRN UT BY MIDDAY TUE. THIS WOULD KEEP THE WEATHER COOL
AND WET ACROSS MUCH OF THE CWA RIGHT THRU THE HOLIDAY WEEKEND
INCLUDING MONDAY. THE GFS HAS MOVED TOWARDS THIS IDEA BUT ITS LOW IS
MORE SHEARED E-W AND IMPACTS MAINLY THE NORTH ON MON. THIS MODEL
DOES HOWEVER HOLD A PIECE OF THE CA LOW OVER NRN UT THRU SUN AND
ALSO KEEPS A THREAT OF PRECIP FOR A LARGER PORTION OF THE CWA ON SUN
THAN IT HAD BEEN SHOWING.

SO WITH THE SLIGHTLY BETTER MODEL AGREEMENT THERE IS MORE CONFIDENCE
THAT THE COOL WET WEATHER WILL HOLD THRU THE ENTIRE HOLIDAY
PERIOD.

&&

.AVIATION...PERIODIC SHOWERS WITH POSSIBLY A THUNDERSTORM OR TWO CAN
BE EXPECTED IN AND AROUND THE KSLC TERMINAL THROUGH THE EVENING.
CONDITIONS WILL PRIMARILY REMAIN IN THE VFR RANGE...ALTHOUGH BRIEF
PERIODS WITH MVFR CIGS/VIS. THE WIND FORECAST IS A LOW CONFIDENCE
ONE...AS OUTFLOW WILL LIKELY DICTATE THE OVERALL WIND PATTERN
THROUGH THE EVENING. THE MOST LIKELY DIRECTION THROUGH 03Z SEEMS TO
BE WEST-NORTHWEST BASED ON MESONET OBSERVATIONS AND SURFACE PRESSURE
ANALYSIS...HOWEVER PERIODS OF SOUTHERLY OR EVEN EASTERLY WINDS WILL
BE POSSIBLE.

&&

.FIRE WEATHER...COOL AND MOIST CONDITIONS WILL BE THE RULE TODAY
ACROSS THE NORTH WHERE CONVECTION WILL BE FAIRLY
WIDESPREAD...PROVIDING A GOOD CHANCE FOR A WETTING RAIN. SNOW LEVEL
IS AROUND 8KFT. MORE ISOLATED TO SCATTERED ACTIVITY IS EXPECTED
ACROSS SOUTHERN AND CENTRAL UTAH WITH DRIER CONDITIONS COMPARED TO
YESTERDAYS HUMIDITY LEVELS.

A WARMING AND DRYING TREND IS FORECAST FOR WEDNESDAY AND THURSDAY.
AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS WILL BE MOST WIDESPREAD
ALONG AND EAST OF THE WASATCH MOUNTAINS.

THE NEXT STORM ARRIVES FRIDAY THROUGH THE HOLIDAY WEEKEND. EXPECT
ANOTHER COOL AND WET PERIOD ACROSS THE ENTIRE REGION.

&&

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

$$

SHORT TERM/FIRE WEATHER...ROGOWSKI
LONG TERM/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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