Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 280417
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
917 PM MST TUE JAN 27 2015

.SYNOPSIS...A COUPLE OF WEAK WEATHER DISTURBANCES WILL CROSS
NORTHERN UTAH TONIGHT THROUGH EARLY WEDNESDAY. THE NEXT STORM
SYSTEM WILL DEVELOP DURING THE LATTER PORTION OF THE WEEK ACROSS
THE GREAT BASIN AND DESERT SOUTHWEST...WITH IMPACTS MAINLY FOR
CENTRAL AND SOUTHERN UTAH THURSDAY NIGHT THROUGH SATURDAY.

&&

.DISCUSSION...SCATTERED SHOWERS WHICH FORMED LATE THIS AFTERNOON
OVER NORTHWEST UTAH REMAIN ACTIVE AT MID-EVENING. THE MID-LEVEL
COLD POOL LIFTING NORTHEAST FROM EAST-CENTRAL NEVADA ALONG WITH
UNSEASONABLY WARM TEMPERATURES PRODUCED A CONVECTIVELY UNSTABLE
FOR THIS SHOWER ACTIVITY TO DEVELOP. DYNAMIC LIFT ALSO APPEARS TO
BE IN PLAY HERE AS WATER VAPOR IMAGERY SHOWS AN APPARENT VORTICITY
MAX EMBEDDED WITHIN THE COLD AIR ALOFT ACROSS EAST-CENTRAL NEVADA
THROUGH NORTHWEST UTAH. CURRENT TIMING WOULD HAVE THIS CURRENT
ROUND OF SHOWERS EXITING NORTHERN UTAH SOMETIME AROUND MIDNIGHT.

FAST ON THE HEELS OF THESE SHOWERS WILL BE A SECONDARY SHORTWAVE
MOVING EAST ACROSS NORTHERN UTAH AND EASTERN IDAHO SHORTLY AFTER
MIDNIGHT. THE AIR MASS UP TO AROUND 700MB WILL REMAIN FAIRLY MOIST
AND UNSTABLE AS THE SHORTWAVE MOVES THROUGH THE AREA. THIS
COMBINATION OF DYNAMIC LIFT AND UNSTABLE AIR SHOULD PRODUCE A
RAPID EXPANSION OF MOSTLY LIGHT PRECIP ACROSS THE NORTH LATE
TONIGHT THROUGH EARLY WEDNESDAY.

HIGH PRESSURE ALOFT WILL BUILD QUICKLY INTO UTAH WEDNESDAY
NIGHT/THURSDAY BEHIND THE EXITING EARLY WEDNESDAY SHORTWAVE.
A RATHER WEAK SHORTWAVE BREAKING AWAY FROM THE MID-LATITUDE
WESTERLIES WILL PHASE WITH A LOW-LATITUDE CIRCULATION NEAR THE
WEST COAST EARLY THURSDAY. THIS FEATURE WILL DRIFT INLAND THURSDAY
THEN GRADUALLY EVOLVE INTO A BROAD CIRCULATION ENCOMPASSING MUCH
OF THE GREAT BASIN AND DESERT SOUTHWEST ON FRIDAY.

THIS SECOND FEATURE WILL FOR A TIME HAVE A TAP INTO SUBTROPICAL
MOISTURE WHICH WILL STREAM NORTH THROUGH MUCH OF UTAH THURSDAY
NIGHT. LIGHT PRECIP COULD BEGIN TO SHOW UP WITHIN THE MOISTURE
SURGE THURSDAY NIGHT...WITH HEAVIER PRECIP POSSIBLY WORKING NORTH
INTO FAR SOUTHERN UTAH LATE THURSDAY NIGHT.

&&

.AVIATION...THE MID-LEVEL WEATHER DISTURBANCE LIFTING NORTHEAST
THROUGH NORTHWEST UTAH THIS EVENING WILL GENERATE LIGHT CONVECTIVE
SHOWERS WEST AND NORTH OF THE TERMINAL THROUGH 05Z-06Z. THESE
SHOWERS WILL MAINTAIN WEST TO NORTH WINDS AS THEY PASS NEAR THE
KSLC TERMINAL...WITH BRIEF GUSTS TO AROUND 20 KTS POSSIBLE. HAZE
OVER THE GSL MAY DRIFT OVER THE TERMINAL AND BRING MVFR VSBYS IN
BRIEFLY THROUGH 06Z.

A SECOND TRAILING WEATHER DISTURBANCE WILL CROSS NORTHERN UTAH
LATER TONIGHT. THIS SECOND FEATURE WILL BRING CEILINGS DOWN TO
AROUND 6000 FEET WITH SHOWERS AT OR NEAR THE TERMINAL THROUGH
WEDNESDAY MORNING. CEILINGS COULD BRIEFLY DROP TO NEAR 4000 FEET
IN HEAVIER SHOWERS BETWEEN 09Z TO 13Z.

&&

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

$$

PUBLIC...CONGER
AVIATION...

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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