Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 192238
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
338 PM MST MON JAN 19 2015

.SYNOPSIS...A WEAK WEATHER DISTURBANCE WILL CROSS NORTHERN UTAH
AND SOUTHWEST WYOMING THIS EVENING. A SECOND SYSTEM WILL IMPACT
EXTREME SOUTHERN UTAH WEDNESDAY...FOLLOWED BY HIGH PRESSURE ALOFT
EXPANDING ACROSS THE WESTERN STATES DURING THE LATTER HALF OF THE
WEEK.

&&

.SHORT TERM (UNTIL 00Z FRIDAY)...SHORTWAVE EXTENDING FROM WESTERN
MONTANA THROUGH NORTH-CENTRAL NEVADA WILL CROSS NORTHERN UTAH
THIS EVENING. ISOLATED VERY LIGHT SHOWERS HAVE FORMED ACROSS THE
NORTH THIS AFTERNOON AND WILL LIKELY PERSIST WITH LIMITED
COVERAGE ACROSS THE NORTHERN MOUNTAINS UNTIL THE SHORTWAVE PASSES
DURING THE EVENING. A SECOND TRAILING VORTICITY LOBE IS LOOKING TO
BE LESS OF A THREAT FOR ADDITIONAL PRECIP EARLY TUESDAY. HAVE
REMOVED EVEN SLIGHT CHANCE POPS FOR THE NORTHERN MOUNTAINS AS THIS
FEATURE LOOKS TO BE SUFFICIENTLY FAR REMOVED FROM OUR FORECAST
AREA.

THE NEXT UPPER TROUGH WILL REACH THE WEST COAST TUESDAY...THEN
SPLIT AS IT MOVES INLAND AHEAD OF A STRENGTHENING UPPER RIDGE OVER
THE EASTERN PACIFIC. THE SOUTHERN END OF THE SPLIT LOOKS TO REMAIN
SOMEWHAT ENERGETIC AS IT TRACKS THROUGH SOUTHERN NEVADA/SOUTHEAST
CALIFORNIA TUESDAY NIGHT...THEN ACROSS ARIZONA WEDNESDAY. PRECIP
WILL FOCUS ALONG AND A LITTLE NORTH OF AN OLD LOW-LEVEL BAROCLINIC
ZONE AS THE SOUTHERN END OF THE SPLIT TROUGH MOVES EAST THROUGH
THE REGION.

THE CURRENT VERSIONS OF THE 18Z GFS/NAM AND 12 ECMWF ARE NOT
OFFERING UP ANY BETTER CHANCE AT PRECIP IN SOUTHERN UTAH. THE
ECMWF CONTINUE TO DRIVE SOUTHERN SPLIT FURTHER SOUTH INTO SOUTHERN
ARIZONA WHILE THE GFS/NAM KEEP THE BAROCLINIC ZONE SUFFICIENTLY
FAR SOUTH TO FOCUS THE BULK OF THE PRECIP OVER NORTHERN ARIZONA.
WILL KEEP A MENTION OF LIGHT PRECIP NEAR THE ARIZONA BORDER AND
ELIMINATE ANY REAL CHANCE NORTH OF BRYCE CANYON IN THE AFTERNOON
FORECAST PACKAGE.

THE EASTERN PACIFIC RIDGE AXIS WILL SHIFT EAST AND ROLLOVER
THROUGH THE GREAT BASIN WEDNESDAY/THURSDAY. SHORTWAVE ENERGY
PASSING OVER AND THROUGH THE RIDGE WILL FIND A RATHER STABLE AND
DRY AIR MASS IN PLACE ACROSS UTAH. PERIODS OF MID/HIGH CLOUDS ARE
EXPECTED WITH POCKETS OF VALLEY FOG IN FAVORED AREAS AND A
BUILDUP OF URBAN HAZE EXPECTED.

&&

.LONG TERM (AFTER 00Z FRIDAY)...GFS AND ECMWF BOTH INDICATE A VERY
WEAK DISTURBANCE WILL DROP SOUTHEAST ACROSS FORECAST AREA LATE IN
THE WORKWEEK...THOUGH ECMWF A BIT FASTER WITH SOLUTION.  WITH VERY
LITTLE MOISTURE TO WORK WITH...SYSTEM NOT EVEN WORTHY OF MENTION OF
PRECIPITATION AT THIS TIME.  700 MB TEMPERATURES DO COOL A COUPLE OF
DEGREES...BUT WITH COOLEST TEMPERATURES ONLY AROUND MINUS 6...WILL
NOT SEE MUCH IN WAY OF ANY INVERSION WEAKENING.

GFS AND ECMWF BOTH NOW INDICATE RIDGE AXIS...JUST OFF PACIFIC COAST
FRIDAY MORNING...SLIDING EASTWARD TO GREAT BASIN BY MONDAY.  WITH
RIDGE AXIS MOVING EASTWARD...WILL SEE SIGNIFICANT WARMING OF 700 MB
TEMPERATURES AND STRENGTHENING VALLEY INVERSIONS.  MODELS DO
INDICATE A WEAK MID LEVEL DISTURBANCE WILL MOVE THROUGH GREAT BASIN
ON TUESDAY...FLATTENING RIDGE.

&&

.AVIATION...CEILINGS AROUND 6000 FT WILL PREVAIL AT SLC UNTIL AROUND
23Z...THEN SHOULD JUST SEE A SCATTERED LAYER.  THERE IS A 20 PERCENT
CHANCE THAT CEILINGS BELOW 7000 FEET WILL LINGER TO AROUND 01Z.
WILL SEE A BRIEF PERIOD OR TWO OF LIGHT PRECIPITATION UNTIL AROUND
00Z...THOUGH NO VISIBILITY RESTRICTION EXPECTED.  NORTHWEST FLOW
SHOULD PREVAIL UNTIL AROUND 06Z...WHEN A DELAYED SOUTHEAST DRAINAGE
FLOW WILL SET UP.  SHOULD SEE A SWITCH BACK TO NORTHWEST FLOW AROUND
17Z TUESDAY MORNING.

&&

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

$$

SHORT TERM...CONGER
LONG TERM/AVIATION...BARJENBRUCH

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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