Area Forecast Discussion
Issued by NWS Salt Lake City, UT

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KSLC 260929
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
329 AM MDT SUN APR 26 2015

.SYNOPSIS...A PACIFIC STORM SYSTEM WILL MOVE THROUGH THE AREA
TODAY. HIGH PRESSURE WILL RETURN BEGINNING MONDAY AND REMAIN
THROUGH MOST OF THE WEEK.

&&

.SHORT TERM (THROUGH 12Z WEDNESDAY)...
WATER VAPOR LOOP SHOWS A TROUGH OVER THE INTERIOR WEST...WITH
ENERGY ON THE BACKSIDE OVER IDAHO POISED TO JOIN THE BASE OF THE
TROUGH CURRENTLY OVER ARIZONA. AMDAR 400-250MB WIND OBSERVATIONS
SHOW A 125-150KT NORTHERLY JET OVER THE PACIFIC NORTHWEST.
GOES/GPS/RAP/00Z SLC RAOB INDICATE THE PRECIPITABLE WATER VALUE
RANGES BETWEEN 0.20"-0.30" MOUNTAINS...TO 0.50"-0.60" ACROSS THE
VALLEYS. BLENDED TOTAL PRECIPITABLE WATER PRODUCT INDICATES MUCH
LOWER THAN TYPICAL VALUES ACROSS THE PACIFIC NORTHWEST...WITH
HIGHER THAN NORMAL VALUES ACROSS THE REMAINDER OF THE WEST.

KEPT A MENTION OF FOG IN THE HIGHER TERRAIN OF CENTRAL AND SOUTHERN
UTAH AS MULTIPLE UDOT SENSORS SHOW LOCALLY DENSE FOG WHERE STRATUS
INTERSECTS THE TERRAIN.

RAP 850-700MB SATURATED EQUIVALENT POTENTIAL
TEMPERATURE/THICKNESS/STREAMLINES SUGGEST THE BAROCLINIC ZONE IS IN
THE PROCESS OF MOVING THROUGH THE WASATCH. AS FLOW VEERS TO A MOIST
UNSTABLE NORTHWEST FLOW...PRECIPITATION RATES EXPECTED TO PICK UP
ALONG THE WASATCH FRONT AND I-15 CORRIDOR EARLY THIS MORNING. CANNOT
RULE OUT ENHANCEMENT OFF THE +14C GREAT SALT LAKE WITH MODIFIED RAP
BUFKIT FORECAST SOUNDINGS SHOWING 1300 J/KG CAPE...EQUILIBRIUM
LEVELS ABOVE 24KFT AND NCAPE GREATER THAN 0.17 THIS MORNING. HAVE
BOOSTED POPS AND QPF DOWNSTREAM OF THE LAKE.

HAVE RETAINED THUNDER EAST OF THE WASATCH THIS AFTERNOON...WHICH
LINES UP WITH 03Z SHORT RANGE ENSEMBLE INSTABILITY PARAMETERS.

WITH 700MB COLD ADVECTION ON 30KTS OF FLOW ALONG WITH A BUILDING
NORTHWESTERLY PRESSURE GRADIENT...EXPECT TO SEE POCKETS EXCEED
ADVISORY CRITERIA FOR A SHORT PERIOD THIS MORNING...INCLUDING POINT
OF THE MOUNTAIN...CASTLE COUNTRY...AND DIXIE...BEFORE DIURNAL
PROCESSES START TO DOMINATE THIS AFTERNOON. LOOK FOR GUSTY WINDS TO
RE-DEVELOP ACROSS OUTLYING DIXIE TONIGHT INTO TOMORROW MORNING
THOUGH 700MB COLD ADVECTION IS BEGINNING TO WANE AS FLOW BECOMES
MORE NORTHEAST. SO THINK WINDS WILL LARGELY REMAIN SUB-ADVISORY.

WITH CLEARING SKIES ACROSS THE WESTERN VALLEYS TONIGHT...CANNOT RULE
OUT A COUPLE RURAL/OUTLYING PARTS NEARING A HARD FREEZE. WILL ALLOW
THE DAY SHIFT TO HONE IN ON THE FORECAST AND DECIDE IF A HEADLINE IS
WARRANTED. MEANWHILE...REMAINING SHOWERS SHOULD WANE ACROSS THE
MOUNTAINS AND EASTERN VALLEYS.

ALSO TONIGHT AS FLOW BECOMES NORTHEASTERLY IN THE WAKE OF THE
STORM ACROSS THE NORTH...COULD SEE ENHANCED CANYON WINDS ALONG THE
WASATCH...PARTICULARLY DAVIS AND WEBER COUNTIES.

ENOUGH INSTABILITY RE-DEVELOPS MONDAY AFTERNOON TO LEAVE A SLIGHT
CHANCE FOR A SHOWER OR STORM IN THE EASTERN MOUNTAINS. OTHERWISE A
RIDGE OF HIGH PRESSURE BUILDS IN PROMOTING A WARMING TREND EARLY IN
THE WORK WEEK.

.LONG TERM (AFTER 12Z WEDNESDAY)...
WARM AND DRY HIGH PRESSURE WILL PERSIST THROUGH AT LEAST
WEDNESDAY...WITH SOUTHWEST FLOW LIKELY TO INCREASE A BIT THROUGH
THE DAY AHEAD OF A TROUGH OVER THE PACIFIC NORTHWEST. A COUPLE
DAYS AGO...THURSDAY LOOKED LIKE THE WARMEST DAY OF THE WEEK...BUT
MODELS HAVE TRENDED MORE PROGRESSIVE AND A LITTLE FARTHER SOUTH
WITH THE INCOMING TROUGH. IN THE 00Z RUNS OF BOTH THE GFS AND
ECMWF...THIS ALLOWS A COLD FRONT TO PUSH THROUGH THE NORTHERN HALF
OF THE CWA ON THURSDAY...POTENTIALLY DENYING THE WASATCH FRONT THE
FIRST 80 DEGREE DAY OF THE YEAR. WHILE THERE WILL NOT BE
CONFIDENCE IN THIS SOLUTION UNTIL THERE IS A LITTLE MORE
CONSISTENCY RUN-TO-RUN...HAVE RAISED POPS AND LOWERED TEMPS A BIT
FOR THURSDAY AFTERNOON.

BEYOND THURSDAY...CONFIDENCE IS LOW IN THE DETAILS OF THE
FORECAST...AS MODELS DIFFER A FAIR AMOUNT IN THE AMPLITUDE OF THE
RIDGE THAT BUILDS AFTER THE TROUGH SLIDES INTO THE GREAT PLAINS...AS
WELL AS HOW MUCH MOISTURE LINGERS INTO FRIDAY AND THE WEEKEND. FOR
NOW...HAVE PUSHED POPS TOWARD CLIMO...IN ANTICIPATION THAT ENOUGH
MOISTURE COULD LINGER TO ALLOW FOR CONVECTION AT LEAST OVER THE
HIGHER TERRAIN. HAVE ALSO GENERALLY KEPT TEMPERATURES ABOVE SEASONAL
NORMALS...AS THE AIRMASS CURRENTLY LOOKS TO BE RELATIVELY WARM
THROUGH AT LEAST SATURDAY.

&&

.AVIATION...THE LARGEST UNCERTAINTY IN THE SALT LAKE CITY TERMINAL
FORECAST FOR TODAY IS HOW LONG RAIN PERSISTS OVER THE AREA THIS
MORNING. THE MOST LIKELY SCENARIO IS FOR RAIN TO DISSIPATE BETWEEN
14Z AND 16Z...BUT THERE IS A CHANCE THAT SHOWERS LINGER THROUGH 18Z.
ONCE SHOWERS END...CEILINGS SHOULD RISE ABOVE MVFR LEVELS...BUT WILL
PROBABLY REMAIN BELOW 7000FT UNTIL 18-21Z.

&&

.FIRE WEATHER...A MOIST PACIFIC STORM SYSTEM REMAINS OVER THE REGION
THIS MORNING...WHICH WILL CONTINUE TO PRODUCE WETTING RAIN AND
ACCUMULATING MOUNTAIN SNOW ACROSS PARTS OF THE AREA THIS MORNING.
SHOWERS WILL DECREASE IN COVERAGE THIS AFTERNOON...AS THE STORM
SLOWLY EXITS THE REGION TO THE EAST. HIGH PRESSURE WILL BUILD OVER
THE AREA STARTING TONIGHT...AND REMAIN IN PLACE THROUGH AT LEAST
WEDNESDAY...PRODUCING A DRYING AND WARMING TREND.

GUSTY NORTH WINDS WILL DEVELOP ACROSS MUCH OF THE AREA TODAY AND
TONIGHT...BEFORE SIGNIFICANTLY LIGHTER AND MORE TERRAIN DRIVEN WINDS
TAKE OVER FOR MONDAY AND TUESDAY.

&&

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

$$

SHORT TERM...ROGOWSKI
FIRE WEATHER...SCHOENING
LONG TERM/AVIATION...SCHOENING

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.