000
FXUS65 KSLC 142220
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
420 PM MDT TUE MAY 14 2013

.SYNOPSIS...A WEAK UPPER LEVEL DISTURBANCE WILL MOVE THROUGH UTAH
TONIGHT THROUGH WEDNESDAY. BEHIND THIS A STRONGER TROUGH WILL MOVE
INTO THE GREAT BASIN LATE IN THE WEEK BRINGING COOLER TEMPERATURES
FOR THE WEEKEND.


&&

.DISCUSSION...AN UPPER LEVEL RIDGE IS DRIFTING SLOWLY EAST ACROSS
THE EASTERN GREAT BASIN TODAY AS A WEAK UPPER LEVEL SHORTWAVE MOVES
INTO SOUTHERN NEVADA. A SHALLOW FRONTAL BOUNDARY HAS PUSHED INTO
CENTRAL UTAH WHERE IT IS EXPECTED TO STALL. MODEST INSTABILITY HAS
DEVELOPED ACROSS MUCH OF THE STATE...SBCAPE OF 250-500 J/KG...AND
ISOLATED CONVECTION HAS FORMED OVER SOUTHERN MOUNTAINS AND THE BOOK
CLIFFS. HRRR RUNS HAVE CONSISTENTLY DEVELOPED ISOLATED CONVECTION
ACROSS ACROSS EAST CENTRAL AND NORTHEAST NEVADA LATE THIS AFTERNOON
AND EVENING AND AS WELL AS INTO PORTIONS OF NORTHERN UTAH.  WITH
MODEST CONVERGENCE AND INSTABILITY ALONG LEADING EDGE OF APPROACHING
SHORTWAVE WILL CONTINUE WITH MENTION OF ISOLATED THUNDERSTORMS THIS
EVENING ACROSS THE NORTH.  THE PRIMARY IMPACT OF ANY STORMS WOULD BE
GUSTY OUTFLOW WINDS IN THEIR VICINITY.  ALSO ADDED A MENTION OF
ISOLATED STORMS FOR EAST CENTRAL AND SOUTHEAST VALLEYS AS STORMS ARE
EXPECTED TO DRIFT OFF OF THE HIGH TERRAIN AND INTO THESE AREAS.

FOR WEDNESDAY...EXPECT HIGH TEMPERATURES TO GENERALLY BE A FEW
DEGREES COOLER IN MOST LOCATIONS ACROSS THE STATE BEHIND WAVE AS IT
MOVES SLOWLY EAST INTO CO.  WILL CONTINUE WITH MENTION OF ISOLATED
CONVECTION OVER UTAH/S HIGH TERRAIN AS WELL AS THE MOST NORTHERN
VALLEYS. INSTABILITY LOOKS TO BE MORE CONFINED TO THE NORTH ON
WEDNESDAY.

FOR THE LATTER PORTION OF THE WEEK INTO THE WEEKEND THE FOCUS SHIFTS
TO AN APPROACHING TROUGH WHICH WILL IMPACT THE GREAT BASIN.  THE
ECMWF AND CANADIAN GEM ARE FASTER WITH THE TROUGH THAN THE GFS AND
HAVE LEANED IN THEIR DIRECTION WITH THE FORECAST. AHEAD OF THIS
TROUGH GUSTY SOUTH WINDS CAN BE EXPECTED ACROSS WEST CENTRAL AND
SOUTHWEST UTAH ON THURSDAY.  TROUGH WILL THEN USHER MUCH COOLER AIR
INTO THE STATE FOR FRIDAY THROUGH THE WEEKEND. HIGH TEMPERATURES FOR
THE WEEKEND WILL BE 10-15 DEGREES COOLER THAN TOMORROW/S HIGHS IN
MANY AREAS ACROSS THE STATE. TROUGH WILL MOVE SLOWLY THROUGH THE
STATE FRIDAY THROUGH SATURDAY NIGHT AND BRING INCREASED COVERAGE OF
SHOWERS AND THUNDERSTORMS TO THE STATE.  THE GREATEST COVERAGE AT
THIS TIME APPEARS TO BE FROM FRIDAY AFTERNOON THROUGH SATURDAY
MORNING.

ON THE BACK SIDE OF THIS TROUGH THE MEDIUM RANGE MODELS CONTINUE TO
INDICATE THE THREAT FOR A SECONDARY WAVE TO DROP INTO UTAH BEFORE
SHORTWAVE RIDGING AND WARMER TEMPERATURES RETURN FOR THE MIDDLE OF
NEXT WEEK.

&&

.AVIATION...THE SLC TERMINAL WILL SEE VFR CONDITIONS THROUGH THE
EVENING WITH SCATTERED CLOUDS. NORTHWEST WINDS ARE EXPECTED TO SHIFT
TO THE SOUTHEAST BETWEEN 04Z AND 06Z. THERE IS A 20 PERCENT CHANCE
THAT ISOLATED SHOWERS IN THE VICINITY OF THE TERMINAL WILL RESULT IN
PERIODS OF GUSTY AND/OR ERRATIC WINDS THROUGH THE EARLY EVENING.

&&

.FIRE WEATHER...A WEAK COLD FRONT SAGGED DOWN INTO NORTHERN UTAH
TODAY BRINGING SLIGHTLY COOLER TEMPERATURES BUT STILL WELL ABOVE
NORMAL. ANOTHER DISTURBANCE WILL MOVE ACROSS THE AREA WEDNESDAY AND
THIS WILL HELP TO DESTABILIZE THE AIRMASS FOR ISOLATED THUNDERSTORMS
OVER THE MOUNTAINS AND MAINLY NORTHERN UTAH IN THE AFTERNOON. A
STRONGER STORM SYSTEM WILL APPROACH THE REGION ON THURSDAY CAUSING
SOUTHWEST SUSTAINED WINDS TO INCREASE TO OVER 20 MPH WITH GUSTS OVER
30 MPH IN THE SOUTH CENTRAL...SOUTHWEST AND WEST CENTRAL VALLEYS
THURSDAY AFTERNOON.

CRITICAL METEOROLOGICAL FIRE WEATHER CONDITIONS ARE EXPECTED TO
OCCUR IN THESE AREAS DUE TO THE COMBINATION OF LOW RH VALUES AND
WINDS. HOWEVER...NO FIRE WEATHER WATCHES OR WARNINGS WILL BE
ISSUED AT THIS TIME DUE TO UNKNOWN FUEL STATUS WHICH IS EXPECTED
TO BE UPDATED EITHER LATER TODAY OR BY WEDNESDAY. IF FUELS ARE
DETERMINED TO BE DRY THE FIRST RED FLAG WARNINGS OF THE SEASON ARE
EXPECTED TO BE INITIATED FOR THIS EVENT.

&&

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

$$

PUBLIC...GRAHAM
FIRE WEATHER...STRUTHWOLF
AVIATION...TRAPHAGAN

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)