Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 271013
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
413 AM MDT WED MAY 27 2015

.SYNOPSIS...AN UPPER LOW MOVING OUT OF THE PACIFIC NORTHWEST WILL
IMPACT MUCH OF UTAH THROUGH THURSDAY. HIGH PRESSURE WILL
STRENGTHEN ACROSS THE REGION LATE IN THE WEEK THROUGH THE UPCOMING
WEEKEND RESULTING IN A WARMING AND DRYING TREND.

&&

.SHORT TERM (THROUGH 06Z SUNDAY)...AN UPPER LOW SPINNING ACROSS
THE INTERIOR PACIFIC NORTHWEST EARLY THIS MORNING WILL GRADUALLY
MEANDER SOUTHEAST ACROSS SOUTHERN ID OVER THE NEXT 24 TO 36 HOURS
BEFORE SHEARING APART AS IT REACHES THE CENTRAL ROCKIES THURSDAY
NIGHT INTO FRIDAY. WHILE THE CENTER OF CIRCULATION WILL REMAIN
JUST NORTH OF THE FORECAST AREA...A SERIES OF PERTURBATIONS
ROTATING AROUND THIS FEATURE WILL BRING SEVERAL WAVES OF SHOWERS
AND THUNDERSTORMS TO NORTHERN AND CENTRAL UT THROUGH THURSDAY.

ONE SUCH WAVE IS CURRENTLY MAKING ITS WAY THROUGH NORTHERN NV
WHERE SHOWERS AND THUNDERSTORMS HAVE PERSISTED OVERNIGHT. HI-RES
MODEL GUIDANCE HOLDS THIS BAND TOGETHER AS IT CROSSES NORTHERN UT
THIS MORNING...WITH ADDITIONAL CONVECTION EXPECTED TO DEVELOP THIS
AFTERNOON FROM A COMBINATION OF DAYTIME HEATING AND A MOIST AND
UNSTABLE BOUNDARY LAYER. FURTHER SOUTH DRIER AIR HAS SPREAD INTO
SOUTHERN UT WHICH SHOULD GREATLY LIMIT CONVECTIVE COVERAGE THIS
AFTERNOON.

AS THE UPPER CIRCULATION CROSSES SOUTHEAST ID TONIGHT INTO EARLY
THURSDAY...THE MODELS HAVE BEEN CONSISTENT IN DEVELOPING
WIDESPREAD PRECIPITATION ACROSS THE NORTHERN HALF OF THE FORECAST
AREA DURING THIS TIMEFRAME. THIS LARGELY RESULTS FROM THE
INFLUENCE OF AN UPPER JET ALONG THE WESTERN PERIPHERY OF THIS LOW
COUPLED WITH A MORE PRONOUNCED VORTICITY LOBE TONIGHT...FOLLOWED
BY A MOIST AND UNSTABLE NORTHWEST FLOW INTO THURSDAY.

BY FRIDAY MID LEVEL RIDGING IS FORECAST TO QUICKLY BUILD ACROSS
THE GREAT BASIN AND REMAIN IN PLACE INTO THE UPCOMING WEEKEND.
LINGERING BOUNDARY LAYER MOISTURE MAY SUPPORT ISOLATED TERRAIN
BASED CONVECTION FRIDAY...OTHERWISE ANTICIPATE A SUBSTANTIAL
WARMING AND DRYING TREND AREAWIDE.

.LONG TERM (AFTER 06Z SUNDAY)...RIDGE AXIS WILL SHIFT SLIGHTLY EAST
SUNDAY IN RESPONSE TO INLAND PROGRESSION OF THE NEXT PACIFIC TROUGH.
A NET INCREASE OF SOUTHWESTERLY FLOW ALOFT COUPLED WITH DEEP MIXING
OF THE AIRMASS WILL PROMOTE BOTH BREEZY SOUTHERLY WINDS AND FURTHER
SURFACE WARMING INTO EARLY NEXT WEEK. MADE MINIMAL CHANGES TO GRIDS
AS THIS PATTERN SHIFT HAS BEEN WELL HANDLED BY PREVIOUS FORECASTS.

TRACK AND EVOLUTION OF AFOREMENTIONED TROUGH HAS PRESENTED MINIMAL
SPREAD IN GLOBAL GUIDANCE SINCE 00Z...ESPECIALLY FOR BEING 5 TO 7
DAYS OUT. AN INITIAL SHORT WAVE IS EXPECTED TO TRACK NORTHEAST
THROUGH NV MONDAY INTO TUESDAY TIGHTENING NEAR H7 BAROCLINICITY
ACROSS FAR NORTHWESTERN UTAH. HIGH BASED CONVECTION POTENTIAL WILL
BE ON THE RISE AS SUCH. A TRAILING SHORT WAVE IS EXPECTED TO THEN
CARVE A BIT FURTHER EAST WITHIN THE MEAN LONGWAVE TROUGH SURGING A
SHALLOW BUT NOTED COLD FRONT THROUGH NORTHERN UTAH LATE
TUESDAY...LIKELY EXPANDING COVERAGE OF ISOLATED TO WIDELY SCATTERED
STORMS ACROSS THE NORTHERN THIRD OF THE AREA INTO WEDNESDAY.

&&

.AVIATION...SIMILAR TO YESTERDAY SHOWERS AND ISOLATED THUNDERSTORMS
WILL MOVE THROUGH KSLC TERMINAL AREA IN THE 15Z-19Z WINDOW. PERIODIC
CIGS AOB 6000FT AGL CAN BE EXPECTED...AND A 10 PERCENT CHANCE EXISTS
THAT LIGHTNING WILL IMPACT THE TERMINAL. A BRIEF BREAK IN
SHOWERS/STORMS IS POSSIBLE BEHIND THIS WAVE MIDDAY...BUT ADDITIONAL
STORMS SHOULD REDEVELOP IN THE VICINITY OF THE TERMINAL MID
AFTERNOON AND LINGER THROUGH THE EVENING.

&&

.FIRE WEATHER...UNSETTLED AND WET CONDITIONS WILL CONTINUE THROUGH
TOMORROW AS A PACIFIC LOW ENCROACHES UPON THEN PASSES THROUGH THE
DISTRICT. PERIODIC SHOWERS AND STORMS ARE EXPECTED TO OCCUR THROUGH
THAT TIME...WITH FOCUS OVER THE NORTHERN HALF OF THE AREA. ELEVATED
WETTING RAIN POTENTIAL WILL CONTINUE.

HIGH PRESSURE WILL BUILD INTO THE DISTRICT BEGINNING FRIDAY AND WILL
STRENGTHEN OVER THE WEEKEND...BEFORE SHIFTING EAST EARLY NEXT WEEK.
SIGNIFICANTLY DRIER AND WARMER CONDITIONS ARE EXPECTED DURING THAT
PERIOD...WITH INCREASINGLY BREEZY SOUTHERLY WINDS BEGINNING SUNDAY
AS ANOTHER PACIFIC TROUGH TRANSITIONS INTO THE EASTERN GREAT BASIN
FOR THE MIDWEEK PERIOD.

&&

&&

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

$$

SEAMAN/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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