Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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791
FXUS65 KSLC 081605
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
905 AM MST MON FEB 8 2016

.SYNOPSIS...STRONG HIGH PRESSURE ALOFT WILL REMAIN THE DOMINANT
WEATHER FEATURE ACROSS THE INTERIOR WEST THROUGHOUT THE WEEK.

&&

.DISCUSSION...WATER VAPOR LOOP SHOWS A RIDGE DOMINATING THE
WEST. AMDAR 400-250MB WIND OBSERVATIONS PLACE A 110-155KT
ANTICYCLONIC JET FROM WESTERN CANADA INTO THE PLAINS.
GOES/HRRR/GPS/12Z SLC RAOB INDICATE THE PRECIPITABLE WATER VALUE
RANGES BETWEEN 0.10"-0.20" MOUNTAINS...TO 0.25"-0.33" NORTHERN
VALLEYS.

WITH AN INVERSION IN PLACE...MAIN CONCERN IS HAZE/FOG AND
TEMPERATURES. ADJUSTED FOG THIS MORNING TO ONLY KEEPING A MENTION
FOR THE CACHE/WASATCH BACK/ALONG THE GREAT SALT LAKE AND UTAH
LAKE/NEAR DELTA.

INVERSION SHOULD CONTINUE TO ALLOW MINIMAL WARMING FRO THE CACHE
VALLEY/BEAR RIVER VALLEY/WESTERN UINTA BASIN AND WEST CENTRAL UTAH.

OTHERWISE JUST A FEW HIGH CLOUDS MOVING IN FROM THE NORTH ALONG
THE PERIPHERY OF THE RIDGE.

&&

.PREVIOUS DISCUSSION...
THE STRONG UPPER RIDGE CURRENTLY CENTER ACROSS THE WEST COAST
STATES WILL SHIFT EAST INTO THE GREAT BASIN TUESDAY. THIS RIDGE
WILL REMAIN THE DOMINANT FEATURE OVER THE REGION THROUGHOUT THE
WEEK.

CONTINUED WARMING ALOFT THROUGH MIDWEEK WILL SERVE TO FURTHER
STRENGTHEN VALLEY INVERSIONS. POOR MIXING UNDERNEATH THE INVERSIONS
WILL RESULT IN INCREASING URBAN HAZE DURING THE WEEK. EXPANDING
AREAS OF FOG ARE ALSO EXPECTED...WITH POCKETS OF DENSE FOG
DEVELOPING NEAR THE GSL...THE CACHE VALLEY AND POSSIBLE IN THE
WASATCH MOUNTAIN VALLEYS THE NEXT COUPLE OF DAYS.

TEMPERATURE TRENDS IN THE NORTHERN AND CENTRAL SNOW COVERED VALLEYS
WILL LIKELY REMAIN STATIC OR EVEN LOWER A BIT IF FOG DEVELOPS DURING
THE SHORT TERM PERIOD. THE EXTREME SOUTHERN AND SOUTHWEST VALLEYS
TEND TO RESPONSE POSITIVELY TO NEAR 700MB WARMING. WILL INCLUDE A
MORE PRONOUNCED WARMING TREND IN THOSE AREAS THROUGH MIDWEEK.

GLOBAL MODELS IN GOOD AGREEMENT WITH RIDGE AXIS SMACK OVERHEAD
FRIDAY AFTERNOON. AFTER THIS POINT THE MODELS DIVERGE AS THE GFS
SPLITS THE ELONGATED TROUGH OFF THE WEST COAST LEAVING A CIRCULATION
AT ITS SOUTHERN END WELL WEST OF BAJA CALIFORNIA AS THE MUCH
WEAKENED NORTHERN PORTION OF TROUGH PROGRESSES THROUGH THE CWA.
WHILE THE EC ALSO SPLITS THE INCOMING TROUGH IT DOES MAINTAIN A
STRONGER NORTHERN BRANCH OF THE TROUGH WHICH MOVES ACROSS NORTHERN
UTAH SATURDAY NIGHT WITH SOME 700MB COLD ADVECTION.
THE EC DOES NOT PRODUCE ANY QPF BUT LEFT TOKEN POPS IN ACROSS THE
MOUNTAINS AS THERE COULD BE SOME SHALLOW INSTABILITY SHOWERS WITH
THE COLD FRONT.

WITH THE 700MB TEMPS COOLING TO BETWEEN -6 TO -8 DEGREES C THIS
SHOULD BE ENOUGH TO BREAK UP THE INVERSION AND CLEAN OUT THE GUNK
ACROSS THE WASATCH FRONT AND CACHE VALLEYS LATE IN THE WEEKEND.
THIS IMPROVEMENT WILL ONLY BE TEMPORARY AS THE RIDGE REBUILDS IN THE
WAKE OF THIS TROUGH.

&&

.AVIATION...HIGH END MVFR CONDITIONS ARE EXPECTED AT THE SLC
TERMINAL THROUGH LATE MORNING. THERE IS A 40 PERCENT CHANCE THAT THE
VSBY REMAINS HIGH END MVFR THROUGH THIS AFTERNOON RATHER THAN
IMPROVING TO 6SM OR GREATER. LIGHT SOUTHEAST WINDS WILL SHIFT TO
NORTHWEST ABOUT 18Z.

&&

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

$$

PUBLIC...ROGOWSKI/CONGER/STRUTHWOLF
AVIATION...VERZELLA

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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