Area Forecast Discussion
Issued by NWS Salt Lake City, UT

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
000
FXUS65 KSLC 241018
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
418 AM MDT THU APR 24 2014

.SYNOPSIS...HIGH PRESSURE WILL MOVE EAST OF THE AREA
TODAY...REPLACED WITH A MILD SOUTHWESTERLY FLOW THE NEXT PACIFIC
STORM SYSTEM WILL IMPACT MUCH OF THE REGION LATE FRIDAY THROUGH
SATURDAY...WITH A SECONDARY SYSTEM CROSSING NORTHERN UTAH SUNDAY.
A COOL NORTHERLY FLOW WILL FOLLOW FOR EARLY NEXT WEEK.

&&

.SHORT TERM (THROUGH 12Z MONDAY)...LOW AMPLITUDE SHORTWAVE
RIDGING IS WORKING ITS WAY EASTWARD ACROSS THE FORECAST AREA THIS
MORNING...DOWNSTREAM FROM A LONGWAVE TROUGH SITTING OFF THE
PACIFIC COAST. AS THIS RIDGE AXIS CONTINUES EASTWARD THIS
MORNING...AN EXTENSIVE PLUME OF MID AND HIGH LEVEL MOISTURE
CURRENTLY CROSSING ACROSS THE GREAT BASIN WILL OVERSPREAD THE
FORECAST AREA. ADDITIONALLY...BACKING FLOW IN THE WAKE OF THIS
RIDGE AXIS WILL ALLOW LOW LEVEL WARM ADVECTION TO DEVELOP AND
STRENGTHEN ACROSS THE FORECAST AREA RESULTING IN A WARMING TREND
AREAWIDE.

THE MODELS REMAIN IN STRONG AGREEMENT BRINGING THE EASTERN PACIFIC
TROUGH INLAND FRIDAY...THEN THROUGH THE GREAT BASIN/INTERMOUNTAIN
WEST FRIDAY NIGHT THROUGH SATURDAY. A LEAD SHORTWAVE EJECTING
AHEAD OF THE MAIN TROUGH IS FORECAST TO BRUSH BY NORTHERN UT
DURING THE DAY FRIDAY...PUSHING A COLD FRONT THROUGH THE NORTHERN
THIRD OF THE AREA FRIDAY AFTERNOON. SOUTH OF THIS FRONT SOUTHERLY
WINDS ARE ONCE AGAIN EXPECTED TO STRENGTHEN...AND ALTHOUGH THESE
WINDS ACROSS CENTRAL AND SOUTHERN UT WILL REMAIN WEAKER THAN WHAT
WAS OBSERVED THIS PAST TUESDAY...ADVISORY LEVEL WINDS ARE
ANTICIPATED AND WILL LIKELY REQUIRE A HEADLINE. ADDITIONALLY...AS
THIS LEAD WAVE EJECTS AHEAD OF THE MAIN TROUGH WILL LIKELY SEE
SCATTERED CONVECTION DEVELOP ACROSS NORTHERN UT ALONG AND NORTH OF
THIS SURFACE BOUNDARY.

LEANED TOWARD THE SLIGHTLY SLOWER AND MORE CONSISTENT ECMWF WITH
RESPECT TO TIMING OF PRECIPITATION FRIDAY NIGHT THROUGH
SATURDAY...GIVEN THE DIGGING...SPLITTING NATURE OF THE UPPER
TROUGH WHICH WOULD SEEM TO SUGGEST A SLOWER EASTWARD PROGRESSION.
AS SUCH HAVE TRIMMED POPS A BIT FRIDAY EVENING PARTICULARLY ACROSS
SOUTHERN UT. OTHERWISE WIDESPREAD VALLEY RAIN/MOUNTAIN SNOW IS
EXPECTED FRIDAY NIGHT ACROSS WESTERN UT...THEN ACROSS THE ENTIRE
CWA DURING THE DAY SATURDAY. MAINTAINED A MENTION OF THUNDER GIVEN
STRONG FORCING...ABUNDANT MOISTURE AND INSTABILITY.

AS THIS WAVE LIFTS NORTHEAST INTO THE CENTRAL ROCKIES SATURDAY
EVENING...WILL LIKELY SEE PRECIPITATION BECOME INCREASINGLY
OROGRAPHIC SATURDAY EVENING WITHIN A MOIST NORTHWEST FLOW...BEFORE
TAPERING OFF EARLY SUNDAY. A SECONDARY WAVE ADVERTISED BY THE BOTH
THE ECMWF AND 00/06Z GFS IS FORECAST TO CROSS NORTHERN UT DURING
THE DAY SUNDAY BRINGING AN ADDITIONAL CHANCE FOR SHOWERS.

&&

.LONG TERM (AFTER 12Z MONDAY)...A LARGE SCALE PATTERN CHANGE EVOLVES
DURING THE LONG TERM...THIS BECOMING SIGNIFICANTLY MORE AMPLIFIED
ACROSS THE WESTERN CONUS VS THE PROGRESSIVE PATTERN AS OF LATE.
EXTENT OF AND LOCATION OF AMPLIFICATION OF THE MEAN RIDGE PROGGED TO
FORM PER GLOBAL GUIDANCE WILL HAVE A DIRECT RESULT ON NAMELY
TEMPERATURES LOCALLY...AND POSSIBLY PRECIP. THE LAST SEVERAL RUNS
DEPICT THE RIDGE AXIS WILL SET UP WELL WEST OF THE FORECAST
AREA...LEAVING US BENEATH NORTHERLY FLOW ALOFT AND SOMEWHAT
SUSCEPTIBLE TO GRAZING WAVES TRACKING DOWN THE DIVIDE. FOR WEDNESDAY
THE ECMWF INDICATES ONE SUCH WAVE WILL SURGE A BACKDOOR COLD FRONT
OUT OF WYOMING INTO THE NORTH PROVIDING SIGNIFICANT COOLING AND A
CHANCE OF PRECIP. GFS INDICATES SLIGHT COOLING BUT DRY CONDITIONS
PREVAILING. DUE TO SOME RUN TO RUN INCONSISTENCIES IN THE EC HAVE
OPTED FOR A DRY SOLUTION FOR NOW...BUT DID COOL TEMPERATURES TO
ACCOUNT FOR MODEL TO MODEL SIMILARITIES IN H7 VALUES. THIS SAID...
CONFIDENCE REMAINS QUITE LIMITED FOR NOW AS ANY SHIFT IN THE RIDGE
AXIS WILL HAVE QUITE AN IMPACT ON SENSIBLE WEATHER LOCALLY.

&&

.AVIATION...OPERATIONAL WEATHER CONCERNS WILL REMAIN LIMITED AT THE
KSLC TERMINAL THROUGH THE VALID TAF PERIOD. PERIODIC CIGS WILL
REMAIN WELL ABOVE 7000FT AGL...AND WINDS WILL SWITCH FROM A LIGHT
SOUTHEAST TO THE NORTHWEST BETWEEN 18-20Z.



&&

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

$$

SEAMAN/MERRILL

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)



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.