Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 162244
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
444 PM MDT SAT AUG 16 2014

.SYNOPSIS...AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL REMAIN OVER
THE REGION THROUGH THE WEEKEND KEEPING A DRY AIRMASS IN PLACE. SOUTHERLY
FLOW AHEAD OF AN UPPER LEVEL LOW ALONG THE CALIFORNIA COAST WILL
SPREAD SOME MOISTURE BACK INTO THE REGION LATE MONDAY AND TUESDAY.


&&

.DISCUSSION...AN UPPER LEVEL RIDGE REMAINS IN PLACE OVER THE GREAT
BASIN THIS AFTERNOON AS AN UPPER LEVEL TROUGH DEVELOPS ALONG THE
PACIFIC NORTHWEST COAST. THIS HAS PLACED UTAH UNDER DRY WEST-
SOUTHWEST FLOW. GOES TOTAL PRECIPITABLE WATER IMAGERY SHOWS DRIER
AIR OVERSPREADING UTAH THIS AFTERNOON WITH PW VALUES DROPPING
BELOW .50" ACROSS MUCH OF WRN UT AND BELOW .75" ACROSS ERN UT.
ALTHOUGH MOISTURE IS DECREASING...THERE IS ENOUGH MOISTURE AND
WEAK INSTABILITY IN PLACE TO LEAVE A MENTION OF ISOLATED
THUNDERSTORMS OVER THE UINTA MTNS AND CENTRAL/SRN UTAH MTNS INTO
THE EVENING. THE THREAT FOR STORMS WILL QUICKLY DISSIPATE WITH
SUNSET AND THE LOSS OF SOLAR INSOLATION.

SUNDAY...UPPER LEVEL RIDGE SHIFTS SLOWLY TO THE EAST AS A CUTOFF
LOW DEVELOPS AND DRIFTS SOUTH ALONG THE NRN CALIFORNIA COAST. AS
THE RIDGE SHIFTS EAST...DRIER AIR WILL CONTINUE TO MOVE INTO
UTAH. UNDER MOSTLY SUNNY SKIES...HIGH TEMPERATURES WILL BE A
COUPLE OF DEGREES ABOVE TODAY/S VALUES ACROSS MOST OF THE STATE
AND WILL BE A BIT ABOVE NORMAL.

MONDAY THROUGH TUESDAY...AS THE UPPER LEVEL RIDGE AXIS SHIFTS
TOWARD THE CENTRAL PLAINS...AND THE CUTOFF LOW MOVES DOWN THE
CALIFORNIA COAST...DEEP SOUTHERLY FLOW BEGINS TO DEVELOP ON
MONDAY. THIS ALLOWS MONSOON MOISTURE...ALTHOUGH IT DOES NOT APPEAR
TO BE A PARTICULARLY STRONG SURGE...TO BEGIN MOVING BACK INTO
SOUTHERN UTAH AND EXPECT THAT WE WILL SEE AT LEAST ISOLATED MTN
CONVECTION IN CENTRAL AND SRN UT. BY TUESDAY...PW VALUES SHOULD
AGAIN INCREASE TO .75" ACROSS CENTRAL AND SOUTHERN UT. ECMWF AND
GFS DEPICT A MID LEVEL WAVE WILL LIFT NORTHEAST INTO UT ON
TUESDAY. THE FORCING WITH THIS FEATURE...COMBINED WITH THE DEEPER
MOISTURE...WILL LEAD TO INCREASED THREAT OF SHOWERS AND STORMS
ACROSS MUCH OF THE STATE...WITH THE LOWEST THREAT BEING IN THE FAR
NORTHWEST. HAVE ELEVATED POPS A BIT IN SOUTHERN AND EASTERN UT TO
ACCOUNT FOR THIS MOISTURE SURGE. ANTICIPATE THAT AFTERNOON HIGHS
WILL DIP A BIT WITH INCREASED CLOUD COVER EXPECTED THROUGH THE
DAY.

WEDNESDAY-SATURDAY...MEDIUM RANGE MODELS BEGIN TO DIVERGE ON THE
HANDLING OF THE CUTOFF LOW FOR WEDNESDAY AND BEYOND. BOTH THE EC
AND GFS DEVELOP A TROUGH OVER THE PACIFIC NORTHWEST DURING THE
MIDDLE TO LATTER PORTION OF NEXT WEEK. THE ECMWF TAKES THE CUTOFF
LOW AND SWINGS IT NORTHEAST THROUGH THE GREAT BASIN AS AN OPEN
WAVE ON THU NIGHT AND FRI...WHILE THE GFS RETROGRADES THE CUTOFF
LOW OFF THE SOUTHERN CA COAST. BOTH SOLUTIONS ARE REASONABLE.
GIVEN THE NOTORIOUSLY DIFFICULT NATURE OF CAPTURING THE EVOLUTIONOF
CUTOFF LOWS NUMEROUS DAYS IN ADVANCE...HAVE NOT MADE SIGNIFICANT
CHANGES TO THE EXTENDED PORTION OF THE FORECAST. ALTHOUGH THE
SOLUTIONS ARE DIFFERENT BOTH THE GFS AND EC INDICATE THE POTENTIAL
FOR MOISTURE TO LINGER THROUGH THE WEEK AND THUS HAVE CONTINUED
WITH THE MENTION OF ISOLATED MOUNTAIN CONVECTION. IF THE EC
SOLUTION IS CORRECT...THE END OF WEEK WOULD CERTAINLY BE MORE
ACTIVE. TEMPERATURES DURING THE LATTER PORTION OF THE WEEK LOOK TO
BE JUST A BIT BELOW NORMAL GIVEN LOWERED HEIGHTS ACROSS THE GREAT
BASIN IN RESPONSE TO THE DEEPENING TROUGH IN THE PACIFIC
NORTHWEST.


&&

.AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD AT KSLC.
LIGHT NORTHWEST WINDS WILL CONTINUE THROUGH THE AFTERNOON BEFORE
SWITCHING BACK TO THE SOUTHEAST BETWEEN 0200-0400 UTC. THERE IS A
10 PERCENT CHANCE THAT SHIFT TO SOUTHEAST WINDS WILL OCCUR AFTER
0400 UTC.

&&

.FIRE WEATHER...WARM AND DRY CONDITIONS WILL PREVAIL THROUGH
SUNDAY BUT THEN SOME MOISTURE RETURNS MONDAY FOR ISOLATED MOUNTAIN
THUNDERSTORMS. A CLOSED LOW MOVING SOUTH OVER CALIFORNIA IS RESPONSIBLE
FOR THIS INCREASE OF MOISTURE AS WINDS ALOFT TURN SOUTHERLY BY MONDAY.
DEEPER MOISTURE WILL SWEEP ACROSS MOST OF THE AREA TUESDAY BUT THEN SHOULD
QUICKLY MOVE OUT OF THE REGION SAVE FOR THE MOUNTAINS BY WEDNESDAY AS
THE FLOW ALOFT BECOMES MORE WESTERLY AGAIN.

&&

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

$$

PUBLIC...GRAHAM
FIRE WEATHER...STRUTHWOLF


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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