Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 061100
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
500 AM MDT WED MAY 6 2015

.SYNOPSIS...THE MOIST AND UNSTABLE AIRMASS ACROSS THE AREA THIS
MORNING WILL GRADUALLY DRY THROUGH THURSDAY. A COLD UPPER LOW
WILL MOVE SOUTH FROM THE PACIFIC NORTHWEST AND SETTLE INTO THE
GREAT BASIN FOR FRIDAY THROUGH THE UPCOMING WEEKEND.

&&

.SHORT TERM (THROUGH 06Z SUNDAY)...THE SHORTWAVE RIDGE MOVING EAST
ACROSS UTAH THIS MORNING IS IN ADVANCE OF THE UPPER LOW MOVING
SOUTH FROM THE PACIFIC NORTHWEST. THIS UPPER LOW WILL SETTLE INTO
CENTRAL CALIFORNIA BY EARLY THURSDAY...THEN TURN EAST AND MOVE
SLOWLY THROUGH THE GREAT BASIN FRIDAY THROUGH SATURDAY NIGHT. THIS
SYSTEM WILL BRING WIDESPREAD AND SUBSTANTIAL PRECIPITATION TO UTAH
THROUGH THE WEEKEND.

THE RATHER MOIST AIRMASS ACROSS THE FORECAST AREA WILL FUEL
ANOTHER DAY OF SHOWERS AND ISOLATED THUNDERSTORMS ACROSS MUCH OF
THE UTAH. FOR EARLY THIS MORNING THE BEST ORGANIZED CONVECTION
EXISTS ACROSS SOUTHWEST UTAH IN ASSOCIATION WITH AN APPARENT WEAK
VORTICITY MAX NEAR THE SOUTHWEST CORNER OF UTAH. SUSPECT THIS
AREA WILL REMAIN CONVECTIVELY ACTIVE THROUGH AT LEAST MID-MORNING
DUE TO THE FAVORABLE AIRMASS...WEAK DYNAMIC LIFT AND THE INTRUSION
OF DRIER AIR AND COLD ADVECTION IN THE MID-LEVELS. FOR THE
REMAINDER OF UTAH THE MOIST AND SOMEWHAT UNSTABLE AIRMASS WILL
SUPPORT SCATTERED LIGHT SHOWERS WITH LITTLE ORGANIZATION UNTIL
LATER TODAY.

THE DRIER SOUTH-SOUTHWEST FLOW ALOFT AHEAD OF THE ABOVE MENTIONED
UPPER LOW WILL SERVE AS A BOUNDARY TO FOCUS CONVECTION ACROSS
CENTRAL UTAH LATER THIS MORNING. LIFT ALONG THIS MOISTURE
DISCONTINUITY SUPPORTED BY THE WEAK VORTICITY MAX SHOULD PRODUCE
SCATTERED OR BETTER CONVECTION THIS MORNING. THIS ACTIVITY WILL
SHIFT TO NORTHERN UTAH THIS AFTERNOON/EVENING. HEAVY RAINS ARE A
GOOD BET WITH THE STRONGER SHOWERS/STORMS WITH SMALL HAIL ALSO A
POSSIBILITY AS THE 700-400MB SHEAR INCREASES ACROSS NORTHERN UTAH
DURING THE AFTERNOON.

BY THURSDAY NIGHT THE DRIER AIR WILL HAVE WORKED ITS WAY NORTH
ACROSS ALL BUT THE FAR NORTHERN PORTIONS OF THE STATE. WILL
MAINTAIN SOME SHOWER/THUNDERSTORM ACTIVITY ACROSS MAINLY NORTHERN
UTAH/SOUTHWEST WYOMING TO ACCOUNT FOR THE POSSIBILITY OF ANY
EJECTING SHORTWAVES FROM THE PARENT UPPER LOW UNDERNEATH DECENT
UPPER DIVERGENCE.

LOOKING AT A LONG DURATION PRECIP EVENT IMPACTING MUCH OF THE
STATE FRIDAY THROUGH AT LEAST SATURDAY EVENING. THE LATEST
VERSIONS OF THE GFS/ECMWF APPEAR QUITE SIMILAR BOTH IN TERMS OF
TIMING AND TRAJECTORY OF THE UPPER LOW ACROSS THE GREAT BASIN
THROUGH SATURDAY EVENING. THE BROAD AREA OF SYNOPTIC-SCALE LIFT
GENERATED BY THE UPPER LOW COMBINED WITH THE LONG DURATION OF THE
EVENT WILL LEAD TO MANY AREAS OF CENTRAL AND NORTHERN UTAH
RECEIVING SUBSTANTIAL PRECIP THROUGH SATURDAY EVENING.

.LONG TERM (AFTER 06Z SUNDAY)...A SLOW MOVING TROUGH WILL BE LOCATED
ACROSS THE INTERIOR WEST AT THE START OF THE LONG TERM FORECAST
PERIOD. THIS TROUGH WILL GRADUALLY MOVE EASTWARD TOWARD THE
CENTRAL PLAINS THROUGH THE DAY SUNDAY...WITH ENOUGH REMNANT MOISTURE
IN PLACE TO CONTINUE THE THREAT OF CONVECTION ACROSS MAINLY THE
HIGHER TERRAIN.

RIDGING IS EXPECTED TO BUILD INTO THE REGION MONDAY...PROVIDING A
BREAK IN THE UNSETTLED CONDITIONS THROUGH TUESDAY. A PACIFIC TROUGH
MOVING AROUND THE TOP OF THE RIDGE THROUGH THE NORTHERN
INTERMOUNTAIN REGION MAY IMPACT THE AREA WEDNESDAY. MODEL TO MODEL
CONSISTENCY HAS IMPROVED FOR THE MONDAY TO TUESDAY PERIOD...BUT IS
STILL A BIT LACKING FOR THE WEDNESDAY SYSTEM. LEFT LOW POPS ACROSS
THE MOUNTAINS OF NORTHERN UTAH MONDAY AND TUESDAY...AS A FEW
AFTERNOON SHOWERS/THUNDERSTORMS WILL BE POSSIBLE. INCREASED POPS
BACK TO CLIMO FOR WEDNESDAY...BUT NOT CONFIDENT ENOUGH IN THE
EVOLUTION OF THE PATTERN AT THIS POINT TO INCREASE POPS ANY FURTHER.

&&

.AVIATION...OCCASIONAL CEILINGS NEAR 5000 FEET AGL WILL BE POSSIBLE
THROUGH ABOUT 12Z AT THE SLC TERMINAL. EXPECT SHOWERS AND A FEW
THUNDERSTORMS TO DEVELOP ACROSS NORTHERN UTAH THIS AFTERNOON AND
EVENING. GUSTY AND ERRATIC OUTFLOW WINDS FROM THIS CONVECTION
MAY IMPACT THE TERMINAL BETWEEN 19-23Z.

&&

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

$$

SHORT TERM...CONGER
LONG TERM/AVIATION...KRUSE

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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