Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 220914
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
314 AM MDT WED OCT 22 2014

.SYNOPSIS...COOL HIGH PRESSURE IS BUILDING INTO THE REGION TODAY.
DRY AND MILD SOUTHWEST FLOW WILL RETURN FOR THURSDAY THROUGH
SATURDAY.

&&

.SHORT TERM (THROUGH 12Z SATURDAY)...
WATER VAPOR LOOP SHOWS YESTERDAYS SYSTEM ALREADY ADVANCING ACROSS
THE NORTHERN ROCKIES. SHORTWAVE RIDGING TRAILS OVER IDAHO...WITH A
DEEP CLOSED LOW OFF THE BRITISH COLUMBIA COAST. AMDAR 400-250MB
WIND OBSERVATIONS REVEAL A CYCLONIC 75-125KT JET OVER THE PACIFIC
NORTHWEST COAST...WITH A 75-95KT NORTHWESTERLY JET OVER THE
WESTERN GREAT BASIN. GOES/GPS/RAP/00Z RAOB INDICATE THE
PRECIPITABLE WATER VALUE RANGES BETWEEN 0.20" NORTHERN
MOUNTAINS...TO 0.70" EASTERN VALLEYS.

SHORTWAVE RIDGING IS THE DOMINATE FEATURE TO OUR NORTH...BUT A
WEAK JET UNDERCUTTING THIS FEATURE IS EXPECTED TO BRING PATCHES OF
HIGH CLOUDINESS ACROSS THE STATE TODAY. A MOIST WESTERLY PACIFIC
FLOW LOOKS TO SUPPLY THICKER AND MORE WIDESPREAD MID AND HIGH
LEVEL CLOUDINESS ACROSS THE FAR WEST AND NORTH TONIGHT THROUGH
THURSDAY NIGHT.

700MB TEMPERATURES REBOUND FROM A LOW THIS MORNING NEAR 0C TO ABOUT
+8C BY THE END OF THE SHORT TERM PERIOD SATURDAY MORNING. BUFKIT
MODEL SOUNDINGS CONFIRM THAT WILL NOT BE MIXING EFFECTIVELY TODAY
WILL A STABLE AIRMASS SETTLING ACROSS THE NORTHERN VALLEYS. UNDERCUT
TYPICAL BIAS CORRECTED GUIDANCE BLEND ACROSS THESE AREAS. DID THE
SAME FOR TOMORROW THOUGH ITS POSSIBLE A FEW VALLEYS BEGIN TO MIX
MORE EFFECTIVELY IN WHAT COULD BE A TRANSITION DAY.

BY FRIDAY...DRY SOUTHWEST FLOW ALOFT STRENGTHENS. 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).

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

&&

.LONG TERM (AFTER 12Z SATURDAY)...
SOUTHERLY WINDS INCREASE OVER THE FORECAST AREA SATURDAY AS THE
RIDGE SHIFTS EAST AHEAD OF THE NEXT APPROACHING PACIFIC NORTHWEST
STORM SYSTEM. 700 MB FLOW IN THE 20 TO 30 KT RANGE WOULD PRODUCE
AT LEAST BREEZY CONDITIONS...ESPECIALLY OVER WESTERN UTAH.

LATEST ECMWF IS A BIT FASTER WITH THE APPROACH OF THE TROUGH AND
ASSOCIATED COLD FRONT...BRINGING IT INTO NORTHERN UTAH SATURDAY
NIGHT AND THROUGH MUCH OF THE REST OF THE STATE SUNDAY MORNING.
CURRENT GFS DOES NOT BRING THE FRONT THROUGH UNTIL SUNDAY MORNING
AND AFTERNOON. BECAUSE OF THIS...ONSET OF PRECIP IS ALSO SLOWER IN
THE GFS. TOTALS ARE GENERALLY LIGHTER AS WELL BECAUSE IT KEEPS THE
INITIAL SHORTWAVE WITH THE SYSTEM NORTH OF THE AREA WHILE THE EC
BRINGS IT ACROSS NORTHERN UTAH WITH THE FRONT. ALL GUIDANCE KEEPS
PRECIP GOING SUNDAY NIGHT/MONDAY MORNING WITH THE MAIN WAVE MOVING
THROUGH AND HAVE INCREASED POPS A BIT DURING THIS PERIOD.

BEHIND THE TROUGH...HIGH PRESSURE IS EXPECTED TO BUILD BACK IN
BEGINNING MONDAY NIGHT/TUESDAY. HOWEVER...THIS RIDGING IS MUCH
WEAKER IN THE LATEST GFS AS IT BRINGS AN IMPRESSIVE LOOKING PACIFIC
STORM INTO THE REGION FOR THE MIDDLE PART OF THE UPCOMING WEEK.
ECMWF IS COMPLETELY OUT OF PHASE...SHOWING STRONG HIGH PRESSURE
DURING THIS PERIOD. BECAUSE OF THIS...HAVE TRENDED TOWARD CLIMO FOR
DAY 7.

&&

.AVIATION...THE SLC TERMINAL WILL SEE VFR CONDITIONS THROUGH THE
MORNING WITH A FEW CLOUDS. LIGHT SOUTHEAST WINDS ARE EXPECTED TO
SHIFT TO THE NORTHWEST BETWEEN 17Z AND 19Z.

&&

.FIRE WEATHER...TEMPERATURES REBOUND GRADUALLY LATE WEEK WITH
DECREASING HUMIDITY. ANOTHER WET COLD FRONT EXPECTED NEXT WEEKEND.
SOUTHERLY WINDS ARE EXPECTED TO BECOME GUSTY AHEAD OF THE FRONT BY
FRIDAY.

&&

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

$$

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

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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