Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 271201
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
501 AM MST TUE JAN 27 2015

.SYNOPSIS...A STORM SYSTEM WILL SLOWLY CROSS THE REGION THROUGH
EARLY WEDNESDAY. ANOTHER SYSTEM WILL DEVELOP DURING THE LATTER
PORTION OF THE WEEK ACROSS THE DESERT SOUTHWEST...AND MY IMPACT
PORTIONS OF CENTRAL AND SOUTHERN UT.


&&

.SHORT TERM (THROUGH 12Z THURS)...AN UPPER LOW CURRENTLY CENTERED
ALONG THE SOUTHERN CA COASTLINE WILL CONTINUE TO FILL AND WEAKEN
TODAY AS IT LIFTS NORTHEAST THROUGH THE GREAT BASIN. THE
ASSOCIATED MID LEVEL TROUGH AXIS IS CURRENTLY SWEEPING NORTHWARD
ACROSS AZ/SOUTHEAST CA...AND HELPING TO FORCE AN ARC OF
PRECIPITATION ACROSS SOUTHERN NV/SOUTHWEST UT. THIS PRECIPITATION
WILL CONTINUE TO SPREAD NORTHWARD WHILE LIKELY DIMINISHING WITH
TIME AS IT SPREADS ACROSS CENTRAL AND EVENTUALLY NORTHERN UT LATER
THIS MORNING THROUGH THIS AFTERNOON. WITH 700MB TEMPERATURES
ONLY FALLING INTO THE -2 TO -3C RANGE PRECIPITATION TYPE WILL
REMAIN LIQUID ACROSS ALL VALLEYS THROUGH THIS AFTERNOON...WITH ANY
HIGHER ELEVATION SNOWFALL REMAINING MINOR.

THE REMNANTS OF THE AFOREMENTIONED UPPER LOW AND ASSOCIATED DEEPER
MOISTURE ARE FORECAST TO GENERALLY LIFT UP AND OVER THE TOP OF THE
FORECAST AREA TONIGHT INTO WEDNESDAY MORNING WITH THE GREATEST
CHANCE FOR PRECIPITATION REMAINING NORTH OF THE FORECAST AREA.
THAT SAID...SUFFICIENT LIFT AND MOISTURE WILL REMAIN PRESENT
ACROSS NORTHERN UT TO BRING ANOTHER PERIOD OF LIGHT HIGHER
ELEVATION SNOWFALL OVERNIGHT INTO WEDNESDAY MORNING...WITH
ACCUMULATIONS AGAIN REMAINING MINOR. THE BEST CHANCE FOR VALLEY
PRECIP LOOKS TO REMAIN NORTH OF I-80 AND IN THE FORM OF RAIN. MID
LEVEL RIDGING WILL BRIEFLY FOLLOW THIS WAVE BRINGING A DOWNWARD
TREND IN PRECIPITATION WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING.

VALLEY INVERSIONS IN PLACE ACROSS NORTHERN UT WILL LIKELY WEAKEN
SIGNIFICANTLY TODAY THROUGH TONIGHT AS 700MB TEMPS CONTINUE TO
COOL INTO THE -5C RANGE BY WEDNESDAY MORNING. MAY NOT COMPLETELY
MIX OUT ALL VALLEYS...BUT DO EXPECT AN IMPROVEMENT IN AIR QUALITY
DURING THIS TIMEFRAME.

&&

.LONG TERM (AFTER 12Z THU)...06Z GFS JUST VIEWED HAS TRENDED TOWARDS
PREVIOUS RUNS OF THE ECMWF REGARDING POSITIONING/EVOLUTION OF THE
UPPER LOW LATE IN THE WEEK. THE NEXT SPLITTING FEATURE POISED TO
TAKE AIM TOWARDS THE WEAKNESS ACROSS THE DESERT SOUTHWEST /LEFT OVER
FROM THE SHORT TERM TROUGH/ LOOKS TO CLOSE OFF EITHER OVER THE
WESTERN UTAH BORDER OR JUST WEST BY THURSDAY NIGHT. SIGNIFICANCE OF
THIS RELATES MOST CLOSELY TO LOCATION OF THE MID LEVEL DEFORMATION
ZONE EXTENDING FROM ITS NORTH AND EAST LEADING UP TO THAT TIME ON
THU.

CONTINUED TO TREND POPS UP ACROSS CENTRAL/SOUTHERN UTAH ALONG AND
BENEATH THIS ANTICIPATED DEFORMATION...BUT IF FUTURE RUNS MAINTAIN
CONSISTENCY POPS REMAIN A FAIR BIT LOW ACROSS THOSE REGIONS AS BOTH
FORCING AND SIGNIFICANT MOISTURE WILL BE PRESENT. AS THE LOW
CONTINUES TO SPIN UP AND GRADUALLY CARVE SOUTH/EAST TOWARDS AND
ALONG THE US/MEXICO BORDER FRIDAY INTO SATURDAY THE DEFORMATION WILL
FOLLOW SUITE...THIS FOCUSING PRECIP MORE AND MORE ACROSS THE
SOUTHERN PORTIONS OF THE AREA. ASSUMING THIS HOLDS TRUE...WILL
FINALLY SEE A MUCH NEEDED MODERATE PRECIP PRODUCER ACROSS NAMELY
SOUTHERN UTAH DURING THAT TIME.

GLOBAL MODELS SUGGESTING A PATTERN SHIFT TO ENSUE THEREAFTER AS A
MORE DEFINED BELT OF WESTERLIES PUNCHES INTO THE WESTERN CONUS LATE
NEXT WEEKEND. SHORT WAVE ENERGY RIDING THIS BELT IS APPARENT IN
GUIDANCE...AND ALTHOUGH CONFIDENCE IN ANY DETAIL REMAINS MINIMAL AT
BEST THAT FAR OUT...OPTED TO TREND POPS TO CLIMO.

&&

.AVIATION...VALLEY HAZE WILL AT TIMES RESTRICT SURFACE VISIBILITY AT
THE KSLC TERMINAL TO MVFR LEVELS THROUGH MUCH OF THIS MORNING.
ADDITIONALLY...A PERIOD OF CIGS AT OR BELOW 6000FT AGL IS EXPECTED
TO OCCUR  AT TIMES IN THE 17-21Z AS THE LEADING EDGE OF A WEAK BUT
MOIST SYSTEM MOVES THROUGH. THE BEST CHANCE FOR LIGHT RAIN SHOWERS
IS IN THIS WINDOW AS WELL AS AFTER MIDNIGHT TONIGHT AS THE WAVE
SKIRTS NORTHERN UTAH.

$$


&&

.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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