Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 182205
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
405 PM MDT SAT OCT 18 2014

.SYNOPSIS...A COUPLE OF WEAK STORM SYSTEMS WILL MOVE ACROSS
ARIZONA THIS WEEKEND WHILE RIDGING WILL REMAIN IN PLACE OVER
NORTHERN UTAH. THE RIDGE WILL BUILD INTO SOUTHERN UTAH MONDAY BUT
A TROUGH AND ASSOCIATED COLD FRONT WILL BREAK DOWN THIS RIDGE ON
TUESDAY.


&&

.DISCUSSION (SHORT TERM...THROUGH 00Z WEDNESDAY)...ELONGATED
TROUGH OVER NEVADA/SOUTHERN CALIFORNIA STARTING TO SHOW SIGNS OF
CLOSING OFF OVER THE LOWER COLORADO RIVER BASIN. THIS CLOSING OFF
PROCESS IS CREATING AN AREA OF DIFFLUENCE OVER SOUTHERN UTAH THIS
AFTERNOON BETWEEN THIS SYSTEM AND THE LOW THAT IS OVER EASTERN NEW
MEXICO. MOISTURE IS LIMITED BUT THERE HAVE BEEN ISOLATED ECHOES
SHOWING UP OVER MAINLY THE HIGHER TERRAIN OF SOUTHERN UTAH THIS
AFTERNOON. THIS SHOULD CONTINUE TO BE THE CASE INTO THIS EVENING
BUT WITHOUT SURFACE HEATING THE DYNAMICS ALOFT ARE NOT LIKELY TO
BE STRONG ENOUGH TO KEEP SHOWERS GOING...THEREFORE DO NOT HAVE ANY
POPS AFTER MIDNIGHT.

ENOUGH MOISTURE OVER THE SOUTHERN MOUNTAINS SUNDAY AFTERNOON UNDER
A VERY NONDESCRIPT FLOW FOR A CONTINUED THREAT OF ISOLATED
SHOWERS. THE NAM SHOWS A LITTLE QPF OVER THE UINTA MOUNTAINS WHILE
THE EC AND GFS DO NOT. DUE TO THE FLOW BECOMING SOUTHERLY SUNDAY
AFTERNOON THERE IS A CHANCE THAT MOISTURE MOVES THAT FAR NORTH SO
HAVE INCLUDED A SPECKLING OF OVER 15 PERCENT POPS OVER THE HIGHER
TERRAIN OF UINTAS BUT NOT ENOUGH TO SHOW UP IN THE ZONE FORECAST.

TEMPERATURES TONIGHT AND SUNDAY SHOULD BE PRETTY MUCH IN LINE
WITH READINGS THAT OCCURRED LAST NIGHT AND TODAY...RESPECTIVELY.
HOWEVER AS WINDS INCREASE OVER WESTERN VALLEYS MONDAY AHEAD OF THE
INCOMING TROUGH...TEMPERATURES SHOULD INCREASE BY 3 TO 6 DEGREES.
THIS WILL PUT THE WESTERN VALLEYS 8-14 DEGREES ABOVE NORMAL, BUT
STILL ABOUT 5 DEGREES BELOW THE PREVIOUS RECORDS FOR OCTOBER 20.

THE EC...GFS AND NAM ARE ALL PRETTY CLOSE IN AGREEMENT ON TIMING
AND STRENGTH OF INCOMING TROUGH ON TUESDAY WITH THE ASSOCIATED
COLD FRONT REACHING SLC AROUND NOON TUESDAY. GUSTY SOUTH WINDS ARE
LIKELY TO DEVELOP IN SOME AREAS MONDAY AFTERNOON THROUGH MONDAY
NIGHT WHICH WILL KEEP TEMPERATURES MILD OVER WESTERN VALLEYS
MONDAY NIGHT. PROBABLY COULD HAVE GONE HIGHER WITH POPS OVER
NORTHERN UTAH TUESDAY SINCE ITS A RESPECTABLE FRONT BUT THERE IS
STILL ROOM FOR THIS FIRST TROUGH TO WEAKEN RAPIDLY WITH A SECOND
ONE RIGHT ON ITS HEALS. SHALLOW COOL AIR SHOULD PUSH ITS WAY INTO
CENTRAL UTAH BY TUESDAY AFTERNOON. LOWERED POPS OVER SOUTHWEST FOR
TUESDAY AS THEY ARE FAR REMOVED FROM ANY DYNAMICS.

.LONG TERM (AFTER 00Z WEDNESDAY)...SIMILAR TRENDS IN GLOBAL GUIDANCE
REGARDING THE SECONDARY SHORT WAVE THAT WILL MOVE THROUGH THE AREA
TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING. TIMING/PLACEMENT REMAIN
LOCKED IN...AND 12Z ECMWF REMAINS 1 TO 2 DEGREES COOLER AT H7 THAN
THE GFS. SAID WAVE WILL SUPPORT MODEST MID LEVEL CAA ACROSS MUCH OF
THE AREA WITH FOCUS ON THE NORTH BUT THIS WILL REMAIN QUITE SHALLOW
OWING TO MINIMAL QPF IN GUIDANCE. WEAK FORCING COUPLED WITH THE
STALLED SURFACE COLD FRONT IN PLACE DOES CONTINUE TO SUPPORT
ISOLATED TO SCATTERED SHOWERS FOCUSED ACROSS THE NORTH/EAST WITH
SNOW LEVELS FALLING TO AT OR JUST BELOW 8000 FEET BY DAWN. MAYBE A
DUSTING ACROSS THE HIGHEST PEAKS BUT THATS ABOUT IT. RAPID
DOWNSTREAM PROGRESSION OF SAID WAVE WILL ALLOW HEIGHTS TO BUILD
RAPIDLY BEHIND WITH CLEARING SKIES WEST TO EAST WEDNESDAY...AND
COOLING TEMPS A FEW DEGREES BELOW CLIMO. DID LOWER MAX TEMPS FOR
THE DAY AS H7 VALUES WILL BE HOVERING BETWEEN 0 TO +1 C IN NORTH.

AFOREMENTIONED BUILDING HEIGHTS A PRECURSOR TO AMPLIFIED RIDGING
THAT WILL TAKE FORM ACROSS THE EASTERN GREAT BASIN FOR THE LATTER
HALF OF THE WEEK. MAINTAINED A DRY FORECAST WITH GRADUALLY
MODERATING TEMPS...SPIKING ABOVE CLIMO FOR NEXT WEEKEND.


&&

.AVIATION...OPERATIONAL WEATHER CONCERNS WILL REMAIN MINIMAL AT THE
KSLC TERMINAL THROUGH THE VALID TAF PERIOD. LIGHT NORTHWEST SURFACE
WINDS WILL SWITCH BACK TO THE SOUTHEAST BETWEEN 03-04Z PER NORM.

&&

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

$$

PUBLIC...STRUTHWOLF
AVIATION...MERRILL

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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