Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 051615
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1015 AM MDT TUE MAY 5 2015

.SYNOPSIS...A LOW PRESSURE SYSTEM OVER NORTHERN ARIZONA WILL MOVE
EAST INTO THE SOUTHERN AND CENTRAL ROCKIES LATER TODAY. A COLD
PACIFIC WEATHER DISTURBANCE WILL MOVE SOUTH OUT OF THE PACIFIC
NORTHWEST AND IMPACT MUCH OF THE GREAT BASIN FRIDAY AND THROUGH
THE WEEKEND.

&&

.DISCUSSION...MORNING WATER VAPOR AND H5 ANALYSIS INDICATE A
CLOSED LOW CENTERED OVER THE 4-CORNERS AND A DEEPER/COLDER CLOSED
UPPER LOW OVER SOUTHERN BRITCOL AND THE FAR NORTHERN PACNW REGION.
A WEAK DEFORMATION AXIS EXISTS ACROSS NORTHERN/WESTERN UTAH FOR
THE TIME BEING. PRIMARY WEATHER FOCUS IN THE NEAR TERM KEYING IN
ON THE 4-CORNERS LOW AND AFOREMENTIONED DEFORMATION AXIS TODAY
INTO TONIGHT AS MODEST FORCING OF AN AIRMASS WITH PWAT RUNNING 1
TO 2 STANDARD DEVIATIONS ABOVE NORMAL WILL YIELD ANOTHER DAY OF
SHOWERS/THUNDERSTORMS TODAY INTO TONIGHT.

PWAT CURRENTLY RANGES FROM .60 TO .80 INCHES WITH HIGHEST TOTALS
OVER SOUTHEASTERN UTAH. SURFACE DEWPOINTS CONTINUE TO CLIMB
MODESTLY AND RANGE FROM THE MID 40S TO AROUND 50 MOST LOCALES.
SYNOPTIC LIFT AROUND THE PERIPHERY OF THE CLOSED LOW CONTINUES TO
GENERATE SCATTERED SHOWERS ACROSS CENTRAL/SOUTHERN UTAH THIS
MORNING...DEFORMATION PROVIDING ENOUGH LIFT FOR SCATTERED SHOWERS
ACROSS THE NORTHWEST DESERTS ATTM. CONTINUED EAST/NORTHEAST
PROGRESSION OF THE LOW INTO COLORADO WILL ALLOW SAID DEFORMATION
TO DISSOLVE BY 00Z...ALLOWING SUBTLE DRYING OF THE AIRMASS ACROSS
FAR NORTHWESTERN PORTIONS THIS AFTERNOON...BUT BULK OF THE AREA
WILL REMAIN VERY MOIST AND INCREASINGLY UNSTABLE WITH ADDED SOLAR
INPUT THIS AFTERNOON. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL CONTINUE TO BE THE NORM ACROSS THE WASATCH FRONT AND POINTS
TO THE SOUTH AND EAST. BULK OF SHORT TERM FORECAST HANDLES THIS
WELL...BUT OPTED TO INCREASE POPS THIS MORNING ACROSS THE
NORTHWEST THEN DECREASE THEM THIS AFTERNOON WITHIN A
DRYING/STABILIZING ENVIRONMENT. OUTSIDE OF THIS MADE ONLY MINOR
INCREASES TO CLOUD COVER TO HANDLE RECENT SATELLITE TRENDS.

GLOBAL MODELS CONTINUE TO TRACK THE PACNW LOW DUE SOUTH INTO
NORCAL BY THIS TIME TOMORROW. A DRYING SOUTHWESTERLY FLOW ACROSS
THE SE PERIPHERY OF THIS WILL BEGIN TO PUNCH INTO FAR SOUTHERN
UTAH TOMORROW MORNING THEN GRADUALLY SPREAD NORTH THROUGH THE DAY
INTO THE OVERNIGHT HOURS. EXPECTING CONVECTION TO FOCUS ALONG A
ZONE OF MID LEVEL CONVERGENT FLOW ON THE NOSE OF THIS
SOUTHWESTERLY FLOW PUSH...WITH FOCUS OF SHOWERS/STORMS LIKELY OVER
CENTRAL UTAH EARLY AFTERNOON SPREADING NORTH INTO NORTHERN UTAH
BY THE EARLY EVENING.

GLOBALS CONTINUE TO PAINT A SIMILAR PICTURE REGARDING TRACK AND
EVOLUTION OF THIS LOW THU THROUGH THE WEEKEND. GENERAL IDEA TURNS
THE LOW EAST THURSDAY EVENING THEN TRACKS THE CORE OF THE UPPER
CIRCULATION THROUGH NORTHERN ARIZONA FRIDAY THROUGH
SATURDAY. ACTIVE WEATHER CAN BE ANTICIPATED THROUGH MUCH OF THE
WEEKEND AS SUCH.

&&

.AVIATION...ANOTHER DAY OF UNSETTLED WEATHER WILL BRING A THREAT
OF GUSTY OUTFLOW WINDS IMPACTING THE KSLC TERMINAL BETWEEN
19-00Z. THERE IS A 20 PERCENT CHANCE OF AN ISOLATED THUNDERSTORM
IMPACTING THE TERMINAL PRIMARILY BETWEEN 20-23Z. OUTSIDE OF THE
GUSTY OUTFLOW POTENTIAL...SURFACE WINDS AT THE SLC TERMINAL WILL
PREVAIL OUT OF THE NORTHWEST THROUGH THE DAY.

&&

.FIRE WEATHER...THIS WEEK WILL GENERALLY BE WET...WITH MOIST RH AND
SEASONAL TO COOL TEMPERATURES.

THE WEATHER TODAY INTO TOMORROW WILL BE DOMINATED BY A SLOW MOVING
DISTURBANCE PROPAGATING FROM THE FOUR CORNERS INTO COLORADO. EXPECT
SCATTERED SHOWERS AND THUNDERSTORMS EACH DAY. DEWPOINTS HAVE RISEN
INTO THE 40S AND 50S INCREASING THE CHANCE OF WETTING RAIN. PRIMARY
THREATS INCLUDE CLOUD TO GROUND LIGHTNING ALONG WITH GUSTY/ERRATIC
WINDS NEAR SHOWERS. SNOW LEVELS SHOULD BE 9-10KFT.

THURSDAY LOOKS TO BE THE DRIEST DAY WITH AN INCREASING GUSTY
SOUTHWESTERLY FLOW AHEAD OF A LARGE STORM SYSTEM DROPPING SOUTH
ALONG THE WEST COAST. THIS STORM WILL MOVE THROUGH THE GREAT BASIN
INTO THE WEEKEND...BRINGING COOLER AND WETTER CONDITIONS ONCE AGAIN.
SNOW LEVELS LOOK TO LOWER BELOW 8KFT BY THE END OF THE WEEK.

&&

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

$$

MERRILL/VERZELLA/ROGOWSKI


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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