Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 052228 CCA
AFDSLC

AREA FORECAST DISCUSSION...CORRECTED SYNOPSIS
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
404 PM MDT SUN JUL 5 2015

.SYNOPSIS...HIGH PRESSURE WILL REMAIN CENTERED OVER THE SOUTHERN
ROCKIES THROUGH MUCH OF THIS WEEK. ABUNDANT MOISTURE ALONG WITH
WEAK WEATHER DISTURBANCES MOVING THROUGH THE REGION WILL GENERATE
SHOWERS AND THUNDERSTORMS THROUGH MIDWEEK. A BROAD UPPER LOW
WILL MOVE THROUGH THE EASTERN GREAT BASIN LATE IN THE WEEK.

&&

.SHORT TERM (THROUGH 06Z WED)...SHORT WAVE THAT MOVED SOUTH TO
NORTH THROUGH THE AREA OVER LAST 24 HOURS HAS SHEARED OVER
SOUTHERN IDAHO TODAY. REMNANT SHORT WAVE ENERGY IS NOW LIMITED TO
A WEAK NEAR STATIONARY DISTURBANCE OVER NORTHWESTERN
NEVADA/SOUTHWESTERN OREGON. A DEFORMATION AXIS REMAINS IN PLACE
OVER SOUTHERN IDAHO BUT IS WEAKENING. PASSAGE OF THE SHORT WAVE
ACROSS THE NORTH EARLY THIS MORNING HAS LEFT MOST AREAS ALONG THE
WASATCH FRONT/BACK QUITE SUPPRESSED...AND ALTHOUGH PWAT REMAINS IN
EXCESS OF 2 STANDARD DEVIATIONS AND SBCAPE IS PUSHING 1500 J/KG
MID LEVEL LAPSE RATES ARE QUITE MEAGER LIMITING UPDRAFT POTENTIAL
FURTHER. THIS CAN BE NOTED IN SHALLOW CONVECTION OVER THE
NORTHWEST DESERTS BEING ONLY LOOSELY ORGANIZED ATTM. DEEPER
CONVECTION SHOULD ACTUALLY BE MORE  EXPANSIVE ACROSS THE
SOUTH/SOUTHEAST THIS EVE WHERE INSTABILITY/PWAT ARE LESS BUT THE
ENVIRONMENT IS LESS SUPPRESSED.

CONVECTIVE POTENTIAL WILL TRANSITION TO A MORE TYPICAL DIURNAL
REGIME OVERNIGHT TONIGHT THROUGH TOMORROW MORNING WITH ACTIVITY
WANING UNTIL THE AFTERNOON. AFOREMENTIONED DISTURBANCE OVER
NORTHWESTERN NV IS PROGGED TO SLIDE EAST ALONG THE UT/NV BORDER
TOMORROW AFTERNOON/EVE AND COULD PROVIDE A BIT OF FORCING AIDING
MAINTENANCE OF SCATTERED CONVECTION OVER THE FAR NORTHERN VALLEY
AREAS...BUT LARGELY CONVECTION SHOULD REMAIN PRIMARILY TERRAIN
BASED BOTH TOMORROW AND TUESDAY.

TEMPERATURES THROUGH THE PERIOD ARE EXPECTED TO REMAIN NEAR
NORMAL...MUCH COOLER THAN THE LAST FEW WEEKS.

.LONG TERM (AFTER 06Z WEDNESDAY)...ECMWF...GFS...AND CANADIAN GEM
ARE IN BETTER AGREEMENT IN THE MEDIUM RANGE WITH THE HANDLING OF THE
UPPER LEVEL LOW DURING THE LATTER HALF OF THE UPCOMING WEEK. CLOSED
UPPER LOW IS PROGGED TO BE JUST OFF OF THE CENTRAL CA COAST AT 1200
UTC WED AND THEN DRIFT SLOWLY OVER CENTRAL CA THROUGH 0000 UTC FRI
BEFORE EJECTING ACROSS THE GREAT BASIN. ALTHOUGH THERE ARE SOME
DIFFERENCES IN THE DETAILS THE MEDIUM RANGE MODELS ARE NOW VERY
SIMILAR IN THIS REGARD. THE GEFS IS ALSO SUPPORTIVE OF THIS SOLUTION
WHICH ADDS CONFIDENCE IN THIS EVOLUTION OF THE UPPER LEVEL PATTERN.

GIVEN THE CONFIDENCE IN THE SLOWER SOLUTION BELIEVE THAT REGION WILL
BE SLOWER TO DRY OUT. THIS EVOLUTION KEEPS WELL FORMED MID LEVEL
DEFORMATION AXIS IN PLACE STRETCHING FROM SW OREGON THROUGH SRN ID
ON WED.  WITH RESIDUAL MOISTURE IN PLACE HAVE EXPANDED POPS ON WED.
MEDIUM RANGE MODELS STILL WANT TO DRY OUT THE AIRMASS SIGNIFICANTLY
ON THU...BUT FEEL THAT IT MAY BE A BIT OVERDONE. ALTHOUGH ONLY REAL
THREAT FOR VALLEY CONVECTION WILL LIKELY BE THE FAR NORTH...BELIEVE
THAT THERE WILL BE THE THREAT FOR STORMS OVER THE HIGHER TERRAIN
NEARLY STATEWIDE AND HAVE EXPANDED POPS THERE A BIT.

ON FRIDAY...UPPER LOW MOVES INTO NV BEFORE BECOMING AN OPEN WAVE AND
LIFTING TO THE NORTHEAST. ALTHOUGH MID LEVEL SOUTHERLY FLOW IS NOT
AS STRONG IN THE MOST RECENT RUN AND THE AIRMASS IS NOT QUITE AS
DRY...WILL STILL NEED TO KEEP A CLOSE EYE ON POTENTIAL FIRE WEATHER
IMPACTS TOWARD OF THE END OF THE WEEK. IN CURRENT MEDIUM RANGE
RUNS...COMBINATION OF CURVATURE EFFECTS AND THE LEFT-EXIT REGION OF
THE UPPER LEVEL JET YIELD A BROAD AREA OF UPPER LEVEL DIVERGENCE
OVER MUCH OF WESTERN AND SOUTHERN UTAH ON FRIDAY. IN ADDITION...
UPPER LOW JUST TO THE WEST OF UTAH RESULTS IN A BAGGY BAROCLINIC
ZONE LIFTING NORTH THROUGH THE STATE...WITH MODEST COLD ADVECTION IN
ITS WAKE. GIVEN THIS POTENTIAL...AS WELL AS THE AFOREMENTIONED UPPER
LEVEL SUPPORT...FEEL THAT THERE IS A DECENT THREAT OF CONVECTIVE
DEVELOPMENT...EVEN WITH LIMITED MOISTURE ASSOCIATED WITH THE
SYSTEM...AND HAVE ADDED A MENTION TO MANY AREAS ACROSS THE STATE.
DRIER AIR SHOULD BE LEFT ACROSS THE REGION BEHIND THIS SYSTEM. THE
ECMWF AND GFS THEN KEEP THE UPPER LEVEL RIDGE CENTERED OVER THE
SOUTH CENTRAL AND SOUTHEASTERN U.S. WHICH KEEPS UTAH UNDER A DRY
SOUTHWEST FLOW ALOFT THROUGH THE WEEKEND.  THE END RESULT IS THAT A
DRIER WEEKEND STILL LOOKS TO BE ON TRACK.

TEMPERATURES THROUGH THE PERIOD ARE EXPECTED TO BE NEAR NORMAL.

&&

.AVIATION...WINDS AT THE KSLC TERMINAL WILL REMAIN NORTHWESTERLY
UNTIL ABOUT 03Z THEN RETURN TO SOUTHEASTERLY. THERE IS A 20 PERCENT
CHANCE THAT A PASSING SHOWER COULD BRING A BRIEF PERIOD OF GUSTY
ERRATIC WINDS UNTIL ABOUT 03Z. VFR CONDITIONS WILL PREVAIL.

&&

.FIRE WEATHER...BULK OF THE DISTRICT REMAINS SUPPRESSED THIS
AFTERNOON IN WAKE OF AN UPPER LEVEL DISTURBANCE THAT MOVED SOUTH
TO NORTH THROUGH THE AREA OVER THE LAST 24 HOURS. SCATTERED
SHOWERS AND A FEW STORMS DO EXIST ACROSS THE SOUTHERN MOUNTAINS
AND NORTHWEST DESERTS HOWEVER. THE RULE OF THUMB FOR MUCH OF THE
WEEK WILL BE A DAILY SHOWER/STORM THREAT EACH AFTERNOON
EVENING...WITH A GRADUAL DRYING TREND AND SLIGHT DOWNTURN IN
WETTING RAIN POTENTIAL.

THE PATTERN SHIFT THAT HAS BEEN ADVERTISED FOR THE LATTER
HALF OF THE WEEK IS LOOKING LESS LIKELY AT THIS TIME.
RATHER THAN HAVING A PROLONGED PERIOD OF DRY AND GUSTY
CONDITIONS...AN UPPER LOW NOW LOOKS TO MOVE THROUGH THE
EASTERN GREAT BASIN FRIDAY.

&&

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

$$

MERRILL/GRAHAM/WILENSKY


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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