AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
530 AM MDT SUN MAY 19 2013
.SYNOPSIS...AN UPPER TROUGH WILL KEEP A COOL MOIST AND UNSTABLE
AIRMASS OVER THE REGION TODAY THROUGH MONDAY MORNING. HIGH PRESSURE
WILL BRIEFLY RETURN ON TUESDAY THEN SHIFT EAST TUESDAY NIGHT. A WARM
DRY SOUTHWEST FLOW WILL DEVELOP WEDNESDAY.
&&
.DISCUSSION...A BROAD DEEP UPPER TROF CENTERED TO OUR EAST COVERS
THE NORTHERN AND CENTRAL ROCKIES AND EXTENDS FROM THE WESTERN PLAINS
TO THE PAC NW. A SHORT WAVE DROPPING INTO THE WESTERN SIDE OF THIS
TROF IS POISED TO CROSS THE CWA TODAY AND LIFT AHEAD OF THIS FEATURE
HAS SET OFF CONVECTION OVER NWRN UT. CELLS HAVE BEEN FORMING OVER
THE GREAT SALT LAKE AND DRIFTING DOWNWIND INTO THE WASATCH FRONT AS
SMALL THUNDERSTORMS THRU THE EARLY MORNING HOURS AND CONTINUE TO DO
SO AT THIS TIME.
EXPECT THIS ACTIVITY TO INCREASE ACROSS MUCH OF THE CWA THRU THE
MORNING AS THE SHORT WAVE ADVANCES AND GETS AN ASSIST FROM DAYTIME
HEATING WITH CELLS BECOMING NUMEROUS OVER THE MTNS THIS AFTN.
MEANWHILE THE DEEP TROF TO OUR EAST STARTS TO CLOSE OFF OVER THE
NORTHERN PLAINS.
CONVECTION WANES ACROSS THE SOUTH THIS EVE BUT MOISTURE WRAPPING
AROUND THE PLAINS LOW ASSOCIATED WITH ONE LAST WEAK SHORT WAVE DROPS
SOUTH INTO THE NRN CWA OVERNIGHT AND KEEPS A THREAT OF PRECIP GOING
OVER THE NORTH INTO MIDDAY MON.
TEMPS WILL REMAIN COOL TODAY THEN START TO MODERATE BACK TOWARDS
NORMAL VALUES MON AS WE START TO DRY OUT AND WARM UP IN THE AFTN.
THE UPSTREAM RIDGE MOVES OVER THE CWA TUE AND BRINGS TEMPS BACK TO
ABOVE NORMAL. THE RIDGE SHIFTS EAST TUE NIGHT AS A NEW DEEP CLOSED
LOW FORMS OVER THE PACNW STATES. MODELS HAVE BEEN STRUGGLING WITH
THE DETAILS OF THIS FEATURE AND HOW FAR EAST THE ASSOCIATED COLD
FRONT GETS BEFORE IT STALLS OUT.
THE EC HAS BEEN FAIRLY CONSISTENT OVER THE LAST SEVERAL RUNS PUSHING
THE FRONT ACROSS NWRN UT WED AND DEVELOPING HIGH BASED CONVECTION
OVER THE NORTHERN CWA AHEAD OF IT TUE NIGHT INTO WED. THE GFS HAS
BEEN LESS CONSISTENT BUT THE LATEST 06Z RUN IS CLOSER TO THE EC THAN
IT HAD BEEN FOR A COUPLE OF DAYS AND BOTH DEVELOP ANOTHER ROUND OF
CONVECTION ALONG THIS FRONT WED AFTN/EVE. IF THE EC IS RIGHT THIS
HAS A POTENTIAL TO BE A HIGH WIND EVENT OVER THE NW DESERTS AND
PORTIONS OF THE WASATCH FRONT WED AFTN AND EARLY EVE.
BOTH MODELS DRAW THE FRONT BACK WWD AGAIN AFTER WED BUT DIFFER ON
TIMING SO CONFIDENCE IN THE TEMPERATURE FORECAST IS LOW.
&&
.AVIATION...VFR CONDITIONS ARE EXPECTED AT THE SLC TERMINAL TODAY.
CIGS SHOULD GENERALLY REMAIN AT OR BELOW 6000 FT AGL WITH SHOWERS
AROUND THE TERMINAL...BUT WILL INCREASE ABOVE 6000 FT AT TIMES IN
BREAKS IN THE SHOWERS. THERE IS A 20 PERCENT CHANCE OF BRIEF MVFR
CONDITIONS DEVELOPING IN HEAVIER SHOWERS AS WELL AS A 20 PERCENT
CHANCE OF A THUNDERSTORM DIRECTLY IMPACTING THE TERMINAL THROUGH
THIS AFTERNOON. SOUTHEAST WINDS ARE EXPECTED TO SHIFT TO THE
NORTHWEST BETWEEN 14Z AND 16Z...BUT SOME SMALL PERIODS OF GUSTY
AND/OR ERRATIC WINDS CAN BE EXPECTED DUE TO THE SHOWERS.
&&
.FIRE WEATHER...THE LAST OF A SERIES OF STORM SYSTEMS WILL MOVE OVER
THE DISTRICT TODAY...KEEPING COOL...MOIST...AND UNSTABLE CONDITIONS
OVER THE AREA THROUGH MONDAY. BREEZY NORTHWEST WINDS ARE POSSIBLE IN
SOME LOCATIONS THIS AFTERNOON AND TOMORROW AFTERNOON AS THE SYSTEM
PASSES. HIGH PRESSURE WILL MOVE OVER THE AREA BEGINNING
TUESDAY...RESULTING IN A WARMING AND DRYING TREND FOR THE MIDDLE TO
LATTER PART OF THE WEEK. SOUTHWEST WINDS COULD BECOME QUITE GUSTY
BEGINNING THURSDAY AHEAD OF A PACIFIC STORM SYSTEM THAT WILL SLOWLY
MAKE ITS WAY TOWARD THE AREA.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...NONE.
&&
$$
WILENSKY/TRAPHAGAN
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VISIT...
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