796
FXUS65 KSLC 191629
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1029 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
LONG WAVE TROUGH EXTENDING FROM WESTERN PLAINS
THROUGH THE EASTERN GREAT BASIN WILL REMAIN IN PLACE TODAY BEFORE
SHIFTING EAST EARLY THIS WEEK. ASSOCIATED UPPER LOW WILL CLOSE OFF
TODAY ACROSS EASTERN MT/WY ALLOWING SHORT WAVE ENERGY TO IMPACT
THE AREA FROM THE NORTHWEST TODAY AND FROM THE NORTH AGAIN
TONIGHT.
A MOIST AND CONDITIONALLY UNSTABLE AIRMASS REMAINS IN PLACE THIS
MORNING PER 12Z KSLC SOUNDING. THIS ALONE ENOUGH FOR TERRAIN BASED
CONVECTION THIS AFTERNOON...BUT ADDED LIFT FROM APPROACHING SHORT
WAVE CURRENTLY OVER NORTHERN NEVADA PER WATER VAPOR WILL ALLOW
FOR AT LEAST SCATTERED VALLEY CONVECTION AS WELL ACROSS THE
NORTHERN 2/3RDS OF THE AREA THROUGH THIS EVENING. GOING FORECAST
IN GOOD SHAPE TO HANDLE SHORT TERM WEATHER...THOUGH DID MAKE MINOR
ADJUSTMENTS TO CLOUD COVER THIS MORNING IN EARLIER UPDATE.
ISOLATED THUNDERSTORMS HAVE CONTINUED TO DEVELOP OVER THE GREAT
SALT LAKE THIS MORNING AS LOW LEVEL INSTABILITY THERE IS GREATER
THAN THAT OVER LAND DUE TO 19C DEGREE LAKE TEMP. IN THE SHORT TERM
THESE CELLS WILL CONTINUE TO STREAM OFF THE LAKE JUST WEST OF THE
WASATCH FRONT...BUT COVERAGE LOOKS TO INCREASE ENOUGH THIS
AFTERNOON TO IMPACT MANY AREAS ALONG THE WASATCH FRONT. BRIEF
HEAVY RAINFALL AND LIGHTNING WILL BE THE PRIMARY THREATS FROM
THESE STRONGER CELLS.
AFOREMENTIONED CLOSED UPPER LOW WILL ROTATE ONE MORE SHORT WAVE
THROUGH NORTHERN UTAH/SOUTHWEST WYOMING FROM THE NORTH-NORTHEAST
TONIGHT INTO THE MORNING. MAY HAVE TO INCREASE POPS FURTHER ACROSS THE
WASATCH BACK SOUTHWEST WYOMING AS MODEL QPF TRENDING TO LOOK MORE
ROBUST IN BOTH AMOUNTS AND COVERAGE THERE.
RIDGING WILL BEGIN TO BUILD TOMORROW THROUGH TUESDAY AS ANOTHER
DEEP UPPER LOW DESCENDS SOUTH FROM AK INTO THE PACNW...CURRENT
TROUGH EXITING EAST. WILL SEE A FAIRLY RAPID RISE TO TEMPS THROUGH
MIDWEEK AS SUCH WITH VALUES SOARING BACK UP TO SOME 10 DEGREES
ABOVE CLIMO ONCE AGAIN ATTM. DETAILS REGARDING PACNW TROUGH AND ASSOCIATED
COLD FRONT WED/THU HAVE REMAINED SUB-PAR FOR SEVERAL
RUNS...THOUGH LAST NIGHTS RUNS BEGINNING TO PHASE TOWARDS THE
ECMWF. AWAITING FULL SUITE OF 12Z GUIDANCE IN HOPES OF PROVIDING
MORE DETAIL TO THE MID/LATE WEEK PERIOD AS THE ASSOCIATED COLD
FRONT WILL NOT ONLY BRING COOLING CONDITIONS...BUT COULD DRIVE
STRONG WINDS ACROSS THE WEST AS WELL.
AVIATION
SURFACE WINDS AT THE KSLC TERMINAL WILL REMAIN OUT OF
THE NORTHWEST FOR THE REMAINDER OF THE DAY...THOUGH PASSING
SHOWERS WILL BRING VARIABLE CONDITIONS TO BOTH SPEED AND
DIRECTION. NOT ANTICIPATED ANY SOUTHERLY FLOW GREATER THAN 5 KNOTS
HOWEVER.
CIGS WILL BE THE PRIMARY OPERATIONAL WEATHER CONCERN AGAIN TODAY.
EXPECTING AN INCREASE IN COVERAGE OF SHOWERS AND ISOLATED STORMS
THROUGH THE AFTERNOON WITH DECKS FILLING IN AROUND THE 6000FT AGL
LEVEL OBSTRUCTING NEIGHBORING TERRAIN. ADDITIONALLY...INSTABILITY
IS GREATER TODAY ALLOWING A SLIGHT INCREASE TO THUNDERSTORM
POTENTIAL TO 30 PERCENT AFTER 18Z.
FIRE WEATHER
A SERIES OF STORM SYSTEMS WILL KEEP A COOL AND WET
PATTERN IN PLACE THROUGH MONDAY. DOWNSLOPE/CANYON WINDS WILL GUST
ACROSS PRONE AREAS ACROSS THE STATE AT TIMES THROUGH MONDAY NIGHT AS
REINFORCING COOLER AIR ARRIVES. IT COULD BE DRY AND BREEZY ENOUGH TO
PRESENT LOCAL CRITICAL FIRE WEATHER CONDITIONS IN DIXIE ON MONDAY.
THE NEXT SYSTEM WILL BRING ANOTHER ROUND OF WETTING RAIN (SNOW ABOVE
7.5KFT) TO NORTHERN AND CENTRAL UTAH TODAY. THE FINAL SYSTEM WILL
MAINLY AFFECT EASTERN UTAH MONDAY.
THE PATTERN SHIFTS AS A RIDGE BUILDS IN TUESDAY AND WEDNESDAY. A
WARMING AND DRYING TREND WILL TAKE PLACE WITH MOISTURE RECOVERIES AT
NIGHT BEGINNING TO LAG.
SOUTHWEST WINDS BEGIN TO DEVELOP TUESDAY NIGHT AS A LARGE STORM
SYSTEM DEVELOPS OVER THE PACIFIC NORTHWEST. THESE WINDS INCREASE AND
BECOME STRONG AND GUSTY WEDNESDAY THROUGH SATURDAY...EXCEPT ACROSS
THE NORTHWEST PORTION OF THE STATE WHERE THEY WILL BE GUSTY FROM THE
NORTHWEST. AT THE SAME TIME...DAYTIME HUMIDITY LEVELS BECOME VERY
DRY...5-12% ACROSS MOST VALLEYS...MAKING FOR WIDESPREAD CRITICAL
FIRE WEATHER CONDITIONS WITH THE ONLY QUESTIONABLE PARAMETER BEING
FUEL STATUS.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...NONE.
MERRILL/ROGOWSKI
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