Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 131630
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1030 AM MDT SUN APR 13 2014

.SYNOPSIS...THE COLD PACIFIC STORM SYSTEM OVER UTAH WILL EXIT THE
STATE THIS AFTERNOON. HIGH PRESSURE ALOFT WILL RETURN MONDAY...
THEN WEAKEN TUESDAY AS A NEW SERIES OF PACIFIC STORM SYSTEMS MOVE
INTO THE REGION MIDWEEK.

&&

.DISCUSSION...THE AXIS OF THE MID-LEVEL TROUGH EXTENDING FROM
WESTERN WYOMING THROUGH SOUTH-CENTRAL UTAH WILL CONTINUE EAST OUT
OF UTAH BY LATE THIS AFTERNOON. GOOD DYNAMIC LIFT WORKING WITH
COLD ADVECTION IN THE 700-400MB LAYER AND SUFFICIENT DEEP LAYER
MOISTURE CONTINUES TO PRODUCE CONVECTION AHEAD OF THE TROUGH OVER
SOUTH-CENTRAL THROUGH EAST-CENTRAL UTAH THIS MORNING. THIS
ACTIVITY WILL CONTINUES EAST WITH THE TROUGH...WITH TRAILING
SUBSIDENCE PRODUCING A BRIEF PERIOD OF DRY CONDITIONS AND MOSTLY
SUNNY SKIES ACROSS THE SOUTHWEST QUADRANT OF UTAH THROUGH EARLY
AFTERNOON.

A SECONDARY VORTICITY MAX TRAILING THE MAIN TROUGH IS PROVING TO
BE A BIT MORE POTENT THIS MORNING. THIS VORTICITY MAX...AND THE
ACCOMPANYING COLD AIR ALOFT...IS POSITIONED JUST TO THE NORTH OF
THE IDAHO BORDER AT MID-MORNING. THE INFLUENCES OF THIS FEATURE
HAVE BEEN REALIZED EARLY AS CONVECTION DEVELOPED QUICKLY AS
DYNAMIC LIFT AND INCREASING INSTABILITY WORK SOUTH INTO NORTHWEST
UTAH. LOOKING AT CONVECTION PEAKING OVER NORTHWEST UTAH BY EARLY
AFTERNOON...THEN INCREASING ACROSS CENTRAL AND SOUTHWEST UTAH AS
THIS FEATURE MIGRATES SOUTH DURING THE DAY. STRONG SUBSIDENCE WILL
RETURN BY EARLY THIS EVENING...BRINGING A QUICK END TO CONVECTION
BY MID-EVENING.

THE UPPER RIDGE AXIS CURRENTLY ALONG THE WEST COAST WILL SHIFT
EAST INTO THE GREAT BASIN FOR TONIGHT THROUGH MONDAY. THIS RIDGE
WILL NOT HAVE ANY STAYING POWER AS A SERIES OF MID-LATITUDE
SHORTWAVES BEGIN TO ERODE THE RIDGE MONDAY NIGHT/TUESDAY. THE GFS
AND ECMWF DIFFER ON THE TRAJECTORY OF THESE DYNAMIC FEATURES...
WITH THE ECMWF KEEP THEM ACROSS THE NORTHERN ROCKIES. THE GFS IN
CONTRAST TENDS TO AMPLIFY THE UPSTREAM RIDGE FASTER OVER THE
EASTERN PACIFIC...ALLOWING FOR THE SHORTWAVES TO DIG SOUTHEAST
ACROSS THE NORTHERN/CENTRAL GREAT BASIN. WATER VAPOR IMAGERY
ACROSS THE CENTRAL INDICATES A MORE ZONAL FLOW WHICH WOULD FAVOR
THE ECMWF SOLUTION OVER THE AMPLIFIED GFS. STILL HAVE UNCERTAINTY
IN THE FORECAST...THOUGH WILL LIKELY SEE POPS A BIT ABOVE CLIMO
ACROSS THE NORTH MIDWEEK.

ISSUED AN EARLIER UPDATE TO ADDRESS CLOUDS AND ADJUST SOME OF THE
SOUTHERN UTAH POPS THROUGH EARLY AFTERNOON.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED AT THE SLC TERMINAL THROUGH
THE DAY...THOUGH CIGS WILL HOVER AROUND 6000 FT AGL WITH SHOWERS IN
THE VICINITY OF THE TERMINAL. PREVAILING WINDS WILL BE WEST TO
NORTHWEST AND GUSTY AT TIMES. HOWEVER...OUTFLOW FROM NEARBY SHOWERS
WILL LIKELY RESULT IN PERIODS OF ERRATIC WIND GUSTS THROUGH THE EARL
EVENING.

&&

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

$$

PUBLIC...CONGER
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)



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