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 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KSLC 091534
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
834 AM MST TUE FEB 9 2016

.SYNOPSIS...STRONG HIGH PRESSURE ALOFT ACROSS THE INTERIOR WEST
WILL REMAIN THE DOMINANT WEATHER FEATURE THROUGH THE BALANCE OF
THE WORK WEEK.

&&

.DISCUSSION...WATER VAPOR LOOP SHOWS A RIDGE DOMINATING THE
WEST. AMDAR 400-250MB WIND OBSERVATIONS PLACE A 140-170KT
ANTICYCLONIC JET FROM WESTERN CANADA INTO THE GULF COAST.
GOES/HRRR/GPS/12Z SLC RAOB INDICATE THE PRECIPITABLE WATER VALUE
RANGES BETWEEN 0.05"-0.15" MOUNTAINS...TO 0.20"-0.30" WESTERN
VALLEYS.

WITH AN INVERSION IN PLACE...MAIN CONCERN IS HAZE/FOG/STRATUS AND
TEMPERATURES. WHILE MANY OBSERVATIONS INDICATE DENSE FOG...WEBCAMS
INDICATE THAT FOG IS PREDOMINATELY OF THE PATCHY VARIETY. HAVE
UPDATED FOG WORDING TO INCLUDE DENSE BUT WILL MAINTAIN PATCHY
DESCRIPTION THIS MORNING.

11-3.9U SATELLITE INDICATES CLEAR CONDITIONS...EXCEPT SOME STRATUS
IS FLOATING AROUND THE WEST DESERT.

GAVE TEMPERATURES ANOTHER LOOK WITH UPDATED GUIDANCE. MOUNTAINS AND
VALLEYS THAT ARE NOT SOCKED IN WITH STRATUS AND FOG WILL CONTINUE TO
SEE A WARMING TREND GIVEN WARMING ALOFT ALONG WITH THE IMPROVING
FEBRUARY SUN ANGLE.

&&

.PREVIOUS DISCUSSION...
THE STRONG UPPER RIDGE ACROSS THE INTERIOR WEST WILL REMAIN THE
DOMINANT FEATURE THROUGH AT LEAST THE END OF THE WEEK. RATHER WARM
TEMPERATURES ALOFT FOR EARLY FEBRUARY WILL MAINTAIN THE STRONG
VALLEY INVERSIONS THE NEXT SEVERAL DAYS.

VALLEY FOG TO THIS POINT HAS REMAINED LIMITED IN AREAL
COVERAGE...WITH MOST OF THIS FOG IN THE CACHE VALLEY...NEAR THE
GSL AND ACROSS PORTIONS OF WEST-CENTRAL UTAH. WILL LIKELY SEE THE
AREAL EXTENT OF THE VALLEY FOG EXPAND A BIT THE NEXT COUPLE OF
DAYS AS ADDITIONAL SNOW MELT PUTS MOISTURE INTO THE BOUNDARY LAYER
ACROSS NORTHERN/WESTERN UTAH. URBAN HAZE WILL ALSO REMAIN IN PLACE
WITH THICKENING/EXPANSION OF THE HAZE AS POLLUTION LEVELS INCREASE
DUE TO POOR MIXING AND LIGHT WINDS.

THE UPPER RIDGE WILL SHOW SLIGHT WEAKENING LATE IN THE WEEK. THIS
CHANGE WILL ALLOW FOR SOME HIGH LEVEL MOISTURE TO MOVE THROUGH THE
REGION BEGINNING WEDNESDAY. THE MAIN IMPACT FROM THE INCREASED
MOISTURE WOULD BE TO GENERATE HIGH CLOUDS WITH SLIGHTLY HIGHER MIN
TEMPS. MAX TEMPS MAY ACTUALLY CLIMB A BIT DUE TO THE WARMER START
IN THE MORNING. VALLEY FOG MAY ALSO DECREASE IN AREAL COVERAGE DUE
TO LESS RADIATIVE COOLING AT NIGHT.

BOTH THE EC AND GFS BRING A WEAK TROUGH ACROSS THE NORTHERN HALF
OF UTAH IN THE EARLY SATURDAY (EC) OR LATE SATURDAY (GFS) TIME
FRAME. THE GFS IS NOT QUITE AS COLD WITH THIS SYSTEM AS THE EC AND
IS JUST SHY OF BEING MARGINALLY UNSTABLE WITH ABOUT 16-17 DEGREES
C DIFFERENCE BETWEEN H7 AND H5. THE MODEL RUNS HAVE CONTINUED A
MINOR THREAT OF SHOWERS IN THE NORTHERN MOUNTAINS SATURDAY NIGHT
INTO SUNDAY...AND THIS LOOKS REASONABLE. THIS DISTURBANCE MAY HAVE
JUST ENOUGH COLD AIR TO TURN OVER THE VALLEY INVERSIONS...BUT
CONFIDENCE REMAINS LOW DUE TO THE VARIATIONS IN MODELS SOLUTIONS.
HAVE LEANED TOWARD THE IDEA OF ERASING THE INVERSIONS IN NORTHERN
VALLEYS WITH TEMPERATURES MODERATING.

&&

.AVIATION...AT THE SLC TERMINAL...THERE IS A 20 PERCENT CHANCE OF
IFR OR WORSE CONDITIONS BETWEEN 16Z AND 19Z DUE TO PATCHY FOG ACROSS
THE AREA. OTHERWISE...VISIBILITIES SHOULD GENERALLY REMAIN IN THE
MVFR RANGE THROUGH MUCH OF THE DAY...THOUGH BRIEF PERIODS OF LOW-END
VFR ARE POSSIBLE AFTER 19Z. WINDS WILL LIKELY BECOME LIGHT NORTHERLY
AROUND 17-19Z...BUT SHOULD REMAIN BELOW 8 KNOTS FROM ANY
DIRECTION THOROUGH TODAY.

&&

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

$$

PUBLIC...ROGOWSKI/CONGER/STRUTHWOLF
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.