Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 240846
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
246 AM MDT FRI OCT 24 2014

.SYNOPSIS...A WARM DRY SOUTHWEST FLOW OVER THE AREA WILL BECOME
STRONGER ON SATURDAY. A STRONG COLD FRONT WILL CROSS UTAH ON
SUNDAY.

&&

.SHORT TERM (THROUGH 12Z MONDAY)...
WATER VAPOR LOOP SHOWS A RIDGE OVER THE ROCKIES...WITH THE NEXT
TROUGH OFF THE PACIFIC NORTHWEST COAST. AMDAR 400-250MB WIND
OBSERVATIONS REVEAL A WESTERLY 140-170KT JET OVER THE PACIFIC
NORTHWEST. GOES/GPS/RAP/00Z RAOB INDICATE THE PRECIPITABLE WATER
VALUE RANGES BETWEEN 0.25" MOUNTAINS...TO 0.50" MOST VALLEYS.

700MB TEMPERATURES HOVER BETWEEN +8C AND +10C THROUGH TOMORROW
MORNING BEFORE BEGINNING TO COOL SIGNIFICANTLY. DRY SOUTHWEST FLOW
ALOFT STRENGTHENS TODAY. AT THE SURFACE...PRESSURE FALLS AND
INCREASING SOUTHEASTERLY PRESSURE GRADIENT SHOULD SUPPORT MUCH
BETTER MIXING. GUSTY SOUTHWEST WINDS ARE FORECAST ACROSS THE WESTERN
VALLEYS AND IN THE HIGHER TERRAIN (GIVEN 500MB FLOW INCREASING TO
40KTS). THESE CONDITIONS CONTINUE THROUGH SATURDAY AND ARE ENHANCED
BY INCREASING PRESSURE GRADIENT AND FALLING HEIGHTS/PRESSURE. EXPECT
WIND GUSTS TO APPROACH OR EXCEED ADVISORY CRITERIA SATURDAY
AFTERNOON ACROSS THE WESTERN VALLEYS.

WENT ABOVE BIAS CORRECTED GUIDANCE FOR LOWS TONIGHT ACROSS THE
WESTERN VALLEYS AND HIGHER TERRAIN GIVEN MINIMIZED DECOUPLING
EXPECTED AHEAD OF THE NEXT STORM SYSTEM.

SHORT RANGE ENSEMBLES INDICATE THAT DESPITE A DRY SOUTHWEST
FLOW...INSTABILITY BEGINS TO INCREASE SATURDAY. INDICATED A FEW
BUILDUPS IN THE SKY GRIDS IN THE HIGHER TERRAIN. FORECAST HIGHS ARE
JUST SHY OF A RECORD FOR SALT LAKE CITY DUE TO THE WARM
START...THOUGH THE THERMAL RIDGE BEGINS TO RETREAT TOWARD THE EAST
AS THE DAY PROGRESSES.

COLD FRONT IS FORECAST TO MAKE ITS WAY INTO NORTHWEST UTAH SATURDAY
NIGHT...CROSSING THE REMAINDER OF NORTHERN UTAH AND SOUTHWEST
WYOMING SUNDAY MORNING. WHILE SOME PRE-FRONTAL SHOWERS MAY DEVELOP
ACROSS THE FAR NORTH SATURDAY NIGHT...BULK OF SHOWER ACTIVITY IS
FORECAST TO ARRIVE WITH BRUNT OF INSTABILITY LATER SUNDAY. SNOW
LEVELS DROP TO ABOUT 7500FT...THOUGH WITH MUCH OF THE COLDER AIR
ALOFT REMAINING NORTH OF THE AREA...NOT ANTICIPATING A LARGE AMOUNT
OF QPF WITH THIS SYSTEM.

WINDS AND COLDER TEMPERATURES ARE PRIMARY ITEMS OF INTEREST WITH
THIS STORM. ALREADY TALKED ABOUT PRE-FRONTAL WINDS...WHICH INCREASE
IN THE HIGHER TERRAIN SATURDAY NIGHT AND REMAIN GUSTY ACROSS
SOUTHEAST UTAH SUNDAY AHEAD OF THE COLD FRONT. WHILE COLD ADVECTION
IS NOT GREAT ACROSS EAST CENTRAL UTAH AND SOUTHWEST UTAH INTO
MONDAY...PRESSURE GRADIENT STRENGTHENS ENOUGH TO PROMOTE GUSTY
DOWNSLOPE/CANYON WINDS ACROSS THESE AREAS POST FRONTAL.

&&

.LONG TERM (AFTER 12Z MONDAY)...
THE TROUGH THAT IMPACTED THE REGION SUNDAY INTO EARLY MONDAY WILL
CONTINUE TO PULL AWAY FROM THE AREA TO BEGIN THE LONG TERM PORTION
OF THE FORECAST. IN THE WAKE OF THE TROUGH...NORTHWESTERLY FLOW IS
EXPECTED TO BUILD INTO THE GREAT BASIN. SEVERAL WEAK DISTURBANCES
EMBEDDED IN THOSE FLOW WILL BRING THE THREAT OF A FEW SHOWERS TO
MAINLY THE NORTHERN MOUNTAINS THROUGH AT LEAST WEDNESDAY.

EXPECT ONE OF THE COLDEST MORNINGS OF THE FALL SEASON SO FAR TUESDAY
MORNING...WITH TEMPERATURES FALLING BELOW THE HARD FREEZE THRESHOLD
OF 28F FOR MANY LOCATIONS OUTSIDE THE URBAN AREAS OF CENTRAL AND
SOUTHERN WASATCH FRONT. HIGH PRESSURE IS THEN EXPECTED TO BUILD INTO
THE AREA BRINGING A WARMING TREND THROUGH AT LEAST FRIDAY.

&&

.AVIATION...LIGHT AND VARIABLE WINDS ARE EXPECTED TO BECOME
SOUTHERLY BETWEEN 14-16Z THIS MORNING AT THE SLC TERMINAL. WINDS
WILL REMAIN SOUTHERLY UNTIL SHIFTING TO THE NORTHWEST BETWEEN
19-21Z.

&&

.FIRE WEATHER...QUITE WARM LATE WEEK WITH LOW HUMIDITY. THE NEXT WET
COLD FRONT EXPECTED ON SUNDAY. SOUTHERLY WINDS ARE EXPECTED TO
BECOME GUSTY AHEAD OF THE FRONT TODAY THROUGH AT LEAST TOMORROW.
SHOWERS ARE FORECAST ACROSS NORTHERN UTAH SUNDAY...WITH THE SNOW
LEVEL DROPPING TO ABOUT 7500 FT. MUCH COOLER AND MORE HUMID HEADING
INTO NEXT WEEK.

&&

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

$$

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

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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