Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 190952
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
352 AM MDT TUE AUG 19 2014

.SYNOPSIS...A MOIST MONSOONAL AIRMASS WILL RESIDE ACROSS THE
REGION TODAY. A WEAK WEATHER SYSTEM WILL MAINTAIN AN UNSETTLED
PATTERN THROUGH THE REMAINDER OF THE WEEK...FOLLOWED BY A DRYING
TREND THIS WEEKEND.

&&

.DISCUSSION...SOUTHERLY FLOW WHICH DEVELOPED DURING THE DAY
MONDAY HAS ALLOWED MOISTURE TO SURGE NORTHWARD ACROSS SOUTHERN
AND CENTRAL UTAH EARLY THIS MORNING...WHERE SURFACE DEW POINTS ARE
GENERALLY RUNNING IN THE LOW TO MID 50S ACROSS VALLEY LOCATIONS.
THIS MOISTURE HAS YET TO REACH NORTHERN UT...WHERE DEW POINTS ARE
RUNNING IN THE LOW TO MID 40S.

OVERNIGHT CONVECTION HAS PERSISTED ACROSS SOUTHERN AND EAST
CENTRAL NV...PARTIALLY OWING TO A REGION OF ASCENT BEING FORCED
BY A COUPLED JET STRUCTURE OVER THE REGION /RIGHT ENTRANCE REGION
OF A 60KT JET EXTENDING ACROSS WY/FAR NORTHERN UT COUPLED WITH THE
LEFT EXIT REGION OF A 70KT JET NOSING INTO THE SOUTHERN GREAT
BASIN. THIS LATTER FEATURE IS ASSOCIATED WITH AN UPPER LOW SLOWLY
DROPPING SOUTH ALONG THE CA COAST.

ONGOING CONVECTION ACROSS EAST CENTRAL NV IS EXPECTED TO SLOWLY
WORK ITS WAY NORTHEAST ACROSS NORTHERN AND CENTRAL UT THIS
MORNING...LIKELY WEAKENING AS IT MOVES INTO A MORE STABLE AND LESS
FORCED ENVIRONMENT. AT PRESENT THE LOCATION OF THE ENTRANCE REGION
OF THE WY JET IS INHIBITING MOISTURE FROM SPREADING MUCH FURTHER
NORTH THAN THE FAR SOUTHERN WASATCH FRONT.

MEANWHILE FURTHER SOUTH...AS THE AFOREMENTIONED UPPER LOW
CONTINUES SOUTHWARD ALONG THE CA COAST...THE ASSOCIATED
DOWNSTREAM JET IS FORECAST TO PIVOT AND SPREAD A BIT
EASTWARD...WITH THE ATTENDANT REGION OF ASCENT SPREADING INTO
SOUTHWEST UT. THE COMBINATION OF INCREASED ASCENT AND AN
INCREASINGLY MOIST AIRMASS...WHICH SHOULD MAINTAIN AT LEAST
MODEST INSTABILITY ACROSS THE REGION...SHOULD YIELD A
CONVECTIVELY DRIVEN HEAVY RAINFALL THREAT ACROSS SOUTHERN AND
PORTIONS OF CENTRAL UT AS EARLY AS THIS MORNING...AND LIKELY
PERSISTING THROUGH THE AFTERNOON HOURS AS IT SLOWLY WORKS
EASTWARD. OF COURSE AS WITH MOST CONVECTIVE EVENTS...ITS POSSIBLE
THE DEGREE OF LARGE SCALE ASCENT OR UPSTREAM CONVECTION RESULTS IN
THE EVENT MORPHING INTO A MORE STABLE AND LESS INTENSE STRATIFORM
EVENT...HOWEVER GIVEN THE CONTINUED INFLUX OF
MOISTURE/INSTABILITY AND LARGE SCALE ASCENT A FLASH FLOOD WATCH
SEEMED WARRANTED THROUGH THIS EVENING ACROSS THIS AREA.

THE CA LOW IS FORECAST TO EVOLVE INTO AN OPEN WAVE AND SLOWLY
SWING EASTWARD ACROSS THE REGION DURING THE WEDNESDAY/THURSDAY
TIMEFRAME...AS A LONGWAVE TROUGH BECOMES ESTABLISHED ACROSS THE
PACIFIC NORTHWEST/NORTHERN ROCKIES. ALTHOUGH THE AIRMASS WILL DRY
CONSIDERABLY FROM WHAT IS CURRENTLY BEING OBSERVED ACROSS THE
REGION...LINGERING MOISTURE COMBINED WITH A CYCLONIC FLOW ALOFT
SHOULD YIELD ISOLATED TO SCATTERED CONVECTION THROUGH THE
REMAINDER OF THE WEEK...AND HAVE BUMPED POPS 10-20 PERCENT AS A
RESULT. THIS FLOW WILL ALSO KEEP TEMPERATURES A BIT BELOW
CLIMATOLOGICAL NORMS THROUGH THE REMAINDER OF THE WEEK.

THE 00Z EC AND GFS DIVERGE WITH THE HANDLING OF THE LONGWAVE
TROUGH BY THE THE WEEKEND...WITH THE GFS FAVORING A LESS AMPLIFIED
SOLUTION WHILE THE EC IS DEEPER AND PUSHES A SHORTWAVE TROUGH INTO
FAR NORTHERN UT LATE SATURDAY/SUNDAY. FOR NOW HAVE MAINTAINED A
DRYING/WARMING TREND FOR LATE IN THE PERIOD.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED AT THE SLC TERMINAL
THROUGHOUT THE DAY. SOUTHEAST WINDS ARE EXPECTED TO SHIFT TO THE
NORTHWEST BETWEEN 21Z AND 23Z. HOWEVER...THERE IS A 30 PERCENT
CHANCE THIS SHIFT WILL NOT OCCUR. HOWEVER...SHOWERS DEVELOPING IN
THE VICINITY OF THE TERMINAL LATE THIS MORNING THROUGH THE AFTERNOON
WILL LIKELY RESULT IN PERIODS OF GUSTY AND/OR ERRATIC WINDS.

&&

.FIRE WEATHER...DEEP MOISTURE IS IN PLACE OVER THE FIRE DISTRICT
TODAY AND SHORTWAVE ENERGY ASSOCIATED WITH A TROUGH ALONG THE
PACIFIC COAST WILL ALSO CAUSE INCREASED INSTABILITY. AS A
RESULT...MUCH OF THE DISTRICT WILL SEE SCATTERED TO NUMEROUS SHOWERS
AND THUNDERSTORMS WITH A GOOD CHANCE OF WETTING RAIN. DRIER AIR WILL
BEGIN TO MOVE IN FOR THE MIDDLE TO LATTER PART OF THE WEEK.
HOWEVER...THE POTENTIAL FOR SCATTERED AFTERNOON SHOWERS AND
THUNDERSTORMS STILL EXISTS...PRIMARILY OVER THE HIGHER TERRAIN.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...FLASH FLOOD WATCH THROUGH THIS EVENING FOR UTZ010-012>014-016-
     019>021-517-518.

WY...NONE.
&&

$$

SEAMAN/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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