Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 021009
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
409 AM MDT SAT MAY 2 2015

.SYNOPSIS...A MILD AND INCREASINGLY MOIST WEST TO SOUTHWEST FLOW
ALOFT WILL REMAIN OVER UTAH THROUGH EARLY NEXT WEEK.

&&

.SHORT TERM (THROUGH 06Z WEDNESDAY)...MID LEVEL RIDGING CENTERED
ACROSS THE DESERT SOUTHWEST WILL WEAKEN AND SLIDE EAST
TODAY...ALLOWING A DEEP LAYER WEST-SOUTHWESTERLY FLOW ALOFT TO
OVERSPREAD THE FORECAST AREA...AND REMAIN IN PLACE THROUGH THE
WEEKEND. MODEST MOISTURE WILL CONTINUE TO SUPPORT A SMALL THREAT
OF HIGH BASED CONVECTION THROUGHOUT THE WEEKEND. THIS ACTIVITY
WILL BY AND LARGE REMAIN DIURNALLY DRIVEN AND TERRAIN BASED...BUT
MAY SPREAD OFF THE TERRAIN INTO ADJACENT VALLEY LOCATIONS AT
TIMES...PARTICULARLY IN CONJUNCTION WITH A COUPLE OF WEAK UPPER
LEVEL PERTURBATIONS PASSING THROUGH THE MEAN FLOW.

A WEAK UPPER LOW IS FORECAST TO MOVE THROUGH THE LOWER CO RIVER
VALLEY MONDAY...THEN EASTWARD ACROSS THE DESERT SOUTHWEST
TUESDAY. ALTHOUGH LARGE SCALE ASCENT ASSOCIATED WITH THIS LOW IS
EXPECTED TO REMAIN SOUTH OF THE AREA...THIS FEATURE MAY ALLOW FOR
AN ADDITIONAL INFLUX OF MOISTURE INTO THE FORECAST AREA EARLY NEXT
WEEK.

&&

.LONG TERM (AFTER 06Z WEDNESDAY)...A WEAK COOL FRONT WILL SLIDE
INTO NORTHERN PORTIONS OF THE CWA WEDNESDAY WHICH WILL HELP TO
FOCUS LIFT AND THEREFORE ENHANCE SOME CONVECTION. THE EC AND GFS
BOTH SHOW THIS FEATURE SO HAVE INCREASED POPS SOME...ESPECIALLY
OVER WESTERN AND NORTHWEST VALLEYS WEDNESDAY AFTERNOON. LOWERED
TEMPS A LITTLE IN THE NORTHWEST SOME AS WELL TO ACCOUNT FOR MORE
SHOWERS AROUND.

THIS BOUNDARY WILL DISSIPATE SOME AND MOVE BACK NORTHWARD SOME ON
THURSDAY AS THE STRONGER TROUGH MOVES INTO NEVADA AND SOUTHERLY
FLOW INCREASES. WIDESPREAD PRECIP IS POSSIBLE ON THE NORTH SIDE OF
THIS BOUNDARY WHICH THE EC PLACES OVER NORTHERN UTAH BUT THE GFS
PUSHES THE FRONT BACK INTO NORTHEAST NEVADA. ONLY MODERATE
CONFIDENCE SO ONLY RAISED POPS TO CHANCE CATEGORY FOR MOST AREAS
OF NORTHERN UTAH. THE EC IS A LITTLE FASTER THAN THE GFS DUE TO
THE GFS BEING DEEPER. THE GREATEST STANDARD DEVIATION FOR GFS
500MB HEIGHTS IS SHOWING UP ON THE BACK SIDE OF THE TROUGH AND A
LITTLE AT THE BASE. THEREFORE THERE ARE SOME ENSEMBLE MEMBERS
HAVING A SECONDARY LOBE MOVING DOWN THE BACKSIDE WHICH PROBABLY
WILL SLOW THE EASTWARD PROGRESSION OF THE TROUGH DOWN SOME. TRIED
TO TIE THIS INTO THE FORECAST BY KEEPING THE HIGHEST POPS OVER THE
WEST WITH LOWER POPS EAST.

&&

.AVIATION...THE SLC TERMINAL WILL SEE VFR CONDITIONS THROUGH THE
TAF PERIOD. SOUTHEAST WINDS ARE EXPECTED TO INCREASE A LITTLE LATE
MORNING EARLY AFTERNOON BEFORE SHIFTING TO THE NORTHWEST ABOUT
20Z. THERE IS A 10 PERCENT CHANCE THAT A GUSTY OUTFLOW WIND COULD
IMPACT THE TERMINAL BETWEEN 21 AND 04Z.

&&

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

$$

SEAMAN/STRUTHWOLF

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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