Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 250334
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
934 PM MDT FRI APR 24 2015

.SYNOPSIS...AN UPPER LEVEL WEATHER DISTURBANCE CROSSING UTAH
OVERNIGHT WILL BE FOLLOWED BY A ENERGETIC PACIFIC STORM SYSTEM
THIS WEEKEND. HIGH PRESSURE WILL RETURN NEXT WEEK.

&&

.SHORT TERM (THROUGH 00Z MONDAY)...THE VORTICITY MAX OVER EXTREME
NORTHEAST NEVADA WITH A LOBE EXTENDING BACK INTO SOUTHERN NEVADA
WILL TRACK EAST ACROSS UTAH OVERNIGHT. SOLID DYNAMIC LIFT NEAR
THE VORTICITY MAX SUPPORTED BY FAIRLY DEEP LAYER MOISTURE/COLD
ADVECTION HAS GENERATED A BROAD AREA OF LIGHT TO MODERATE VALLEY
RAIN AND HIGH ELEVATION SNOW WITH ISOLATED THUNDERSTORMS ACROSS
NORTHWEST UTAH. THIS ORGANIZED PRECIP WILL MOVE EAST WITH THE
VORTICITY MAX...LEAVING LINGERING LIGHT INSTABILITY SHOWERS IN
ITS WAKE LATE TONIGHT.

LIGHT SHOWERS HAVE EXPANDED IN AREAL COVERAGE ACROSS WEST-CENTRAL
AND SOUTHWEST UTAH IN ASSOCIATION WITH THE SOUTHERN END OF THE
VORTICITY LOBE CURRENTLY NEAR THE UTAH/NEVADA BORDER. THIS PRECIP
WILL REMAIN LIGHT THIS EVENING...THEN EXPAND AND BECOME HEAVIER
ACROSS CENTRAL UTAH LATER TONIGHT AS COLD ADVECTION ALOFT
INCREASES OVER THE REGION.

A SHORT LULL IN THE HEAVIER PRECIP SHOULD DEVELOP EARLY SATURDAY
IN ADVANCE OF THE MAIN TROUGH ELONGATING NORTHWEST TO SOUTHEAST
ACROSS THE WESTERN GREAT BASIN. THIS NOW ELONGATED TROUGH WILL
CONTINUE EAST...REACHING INTO WESTERN UTAH LATE SATURDAY THEN
SETTLE SQUARELY OVER UTAH SATURDAY NIGHT. WIDESPREAD PRECIP WILL
EXIST IN THE COOL/MOIST AIR MASS EMBEDDED IN THE BROAD AREA OF
SYNOPTIC-SCALE LIFT OVER THE FORECAST AREA. TEMPERATURES ALOFT
WILL BE SUFFICIENTLY COLD TO ALLOW FOR SEVERAL INCHES OF NEW SNOW
TO ACCUMULATE AT THE HIGHER ELEVATIONS.

BY EARLY SUNDAY THE UPPER JET DIVING SOUTH IN BEHIND THE TROUGH
WILL ENERGIZE THE SOUTHERN PORTION OF THE TROUGH...LEADING TO THE
FORMATION OF A CLOSED LOW NEAR OR A LITTLE SOUTH OF THE FOUR
CORNERS REGION. THE HEAVIER PRECIP WILL SHIFT INTO EASTERN AND
CENTRAL UTAH IN THE WRAP AROUND ALONG THE NORTHERN FLANK OF THE
NOW DEVELOPED UPPER LOW. AREAS OF WESTERN AND NORTHERN UTAH WILL
ALSO SEE SHOWERS PERSIST MUCH OF THE DAY...WITH THE HEAVIEST
PRECIP LIKELY HUGGING THE I-15 CORRIDOR ALL THE WAY SOUTH THROUGH
THE STATE.

&&

.PREVIOUS LONG TERM (AFTER 00Z MONDAY)...THE EC AND GFS ARE IN
AGREEMENT WITH THE CLOSED LOW MOVING INTO NEW MEXICO SUNDAY NIGHT
BUT BOTH HOLD ONTO WRAP AROUND MOISTURE REMAINING ACROSS SOUTHWEST
WYOMING AND THE HIGHER TERRAIN OF THE EASTERN PORTION OF OUR CWA
SUNDAY NIGHT INTO MONDAY. THEREFORE HAVE HELD ONTO SOME LOW POPS
IN THESE AREAS INTO MONDAY.

A STRONG RIDGE MOVES INTO THE REGION LATER MONDAY THROUGH WEDNESDAY
FOR DRY CONDITIONS AND A WARMING TREND. HOWEVER HAVE BACKED OFF BY A
COUPLE OF DEGREES ON THE WARMING FOR MONDAY AND TUESDAY AS A
NORTHERLY FLOW WILL REMAIN AND TYPICALLY WE DO NOT WARM AS RAPIDLY
UNDER A NORTHERLY FLOW REGIME. BY WEDNESDAY THE FLOW BECOMES
SOUTHERLY WHICH WILL ALLOW TEMPERATURES IN SOME PLACES TO WARM TO
THE HIGHEST LEVELS SO FAR THIS YEAR. IF THEY DO NOT REACH THE PEAK
ON WEDNESDAY THEY SHOULD REACH A PEAK ON THURSDAY AS WINDS INCREASE
SOME AHEAD OF A POSSIBLE TROUGH. HOWEVER THE EC AND GFS ARE NOT IN
AGREEMENT ON THE STRENGTH OR TIMING OF THIS SYSTEM SO CONFIDENCE NOT
VERY HIGH.

LEFT A FEW SHOWERS OVER THE HIGHER TERRAIN FOR THURSDAY AND FRIDAY
DUE TO THE MID LEVELS SHOWING SOME MOISTENING BUT AGAIN ITS ONLY A
SLIGHT CHANCE AT THIS TIME.

&&

.AVIATION...THE UPPER LEVEL WEATHER DISTURBANCE MOVING EAST-NORTHEAST
ACROSS NORTHWEST UTAH WILL BRING OCCASIONAL MVFR CEILINGS/VSBYS IN
RAIN TO THE TERMINAL THROUGH AROUND 05Z. RAIN AFTER 05Z WILL
PERSIST THROUGH AROUND 08Z-09Z WITH PREVAILING CEILINGS BETWEEN 3
AND 4 KFT IN PRECIP. A BRIEF BREAK IN PRECIP LATE TONIGHT/EARLY
SATURDAY WILL GIVE WAY TO AROUND OF RAIN WITH OCCASIONAL MVFR
CEILING/VSBY CONDITIONS FROM LATE SATURDAY MORNING THROUGH THE
EVENING HOURS.

&&

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

$$

SHORT TERM/AVIATION...CONGER
LONG TERM...STRUTHWOLF

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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