Area Forecast Discussion
Issued by NWS Salt Lake City, UT

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KSLC 251035
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
335 AM MST SUN JAN 25 2015

.SYNOPSIS...STRONG HIGH PRESSURE WILL BUILD INTO THE WESTERN
STATES THROUGH TOMORROW. THE NEXT STORM SYSTEM APPROACHING FROM
THE SOUTHWEST WILL IMPACT THE AREA MONDAY NIGHT THROUGH WEDNESDAY.

&&

.SHORT TERM (THROUGH 12Z WEDNESDAY)...
WATER VAPOR LOOP SHOWS AN EXPANSIVE EASTERN PACIFIC RIDGE
BUILDING INTO THE REGION WITH A CLOSED LOW OFF OF BAJA. AMDAR
400-250MB WIND OBSERVATIONS INDICATE A 125-160KT ANTICYCLONIC JET
FROM BRITISH COLUMBIA OVER THE NORTHERN AND CENTRAL ROCKIES.
GOES/GPS/RAP/00Z RAOB INDICATE THE PRECIPITABLE WATER VALUE RANGES
BETWEEN 0.15-0.25" MOUNTAINS...TO 0.30-0.50" MOST VALLEYS. BLENDED
TOTAL PRECIPITABLE WATER PRODUCT INDICATES VALUES MUCH BELOW
NORMAL ACROSS THE SOUTHWEST...WITH A MOISTURE TAP INTO THE PACIFIC
NORTHWEST AND NORTHERN ROCKIES.

RIDGETOP TEMPERATURES CONTINUE THE WARMING TREND THROUGH MONDAY.
WITH RIDGING SURFACE AND ALOFT DOMINATING...EXPECT INVERTED
CONDITIONS TO INTENSIFY. STATUS WHICH BUILT IN ACROSS THE NORTH AND
WEST YESTERDAY IS EXPECTED TO GRADUALLY ERODE FROM WEST TO EAST
THROUGH THIS EVENING PER RAP 850-700MB DRYING DEPICTION AS THE
ANTICYCLONE BUILDS INTO IDAHO.

NOT A LOT OF VALLEY SNOW COVER SO NO SIGNIFICANT CHANGES TO VALLEY
TEMPERATURE TRENDS. AIR QUALITY ON THE OTHER HAND EXPECTED TO
DETERIORATE THROUGH EARLY NEXT WEEK. KEPT MENTION OF HAZE INTO THE
URBAN CORRIDOR MONDAY AFTERNOON.

THE AFORMENTIONED CLOSED LOW IS DEPICTED TO LIFT ALONG THE SOUTHERN
CALIFORNIA COAST INTO TUESDAY MORNING. TROPICAL MOISTURE LIFTS
NORTHWARD AS THE RIDGE DEPARTS TO THE EAST. EJECTING WEAKENING WAVES
WITHIN DIFFLUENT FLOW LIKELY TO SUPPORT SHOWER ACTIVITY DEVELOPING
ACROSS SOUTHERN UTAH MONDAY NIGHT. MANY LOCATIONS WOULD SEE
RAIN...WITH THE SNOW LEVEL EXPECTED TO RANGE BETWEEN 7-8KFT.

MOISTURE EXPECTED TO GRUDALLY DIMINISH AS IT PROPAGATES NORTH ACROSS
NORTHERN UTAH TUESDAY. BY AFTERNOON...SHORT RANGE ENSEMBLES INDICATE
DESTAILIZATION...AND WITH MOISTURE REGIEME KEPT MENTION OF ISOLATED
TO SCATTERED SHOWERS ACROSS THE STATE. SNOW LEVELS LARGELY UNCHANGED
THROUGH THE DAY.

THE REMNANT CIRCULATION CENTER OVER NORTHEAST NEVADA LATE TUESDAY IS
SHOWN TO CROSS NORTHERN UTAH TUESDAY NIGHT. THIS SHOULD ENHANCE
PRECIPITATION GIVEN BETTER ORGANIZATION TO THE DYNAMICS...AND COOL
ADVECTION. SNOW LEVELS WILL START TO LOWER TOWARD 6KFT AS MORE OF AN
ORAGRAPHIC WEST-NORTHWEST FLOW DEVELOPS LATE IN THE NIGHT.

&&

.LONG TERM (AFTER 12Z WED)...
GLOBAL MODEL GUIDANCE SUGGESTS THE OPEN WAVE PRECIPITATION ACROSS
THE NORTHERN HALF OF THE CWA WILL BECOME MORE OROGRAPHIC IN NATURE
WED MORNING AS THE SHORT WAVE ENERGY CONTINUES ITS EASTERLY
DOWNSTREAM TRAJECTORY. HAVE UPPED POPS ALONG THE WASATCH
FRONT/SPINE TO ACCOUNT FOR THE MOST FAVORABLE AREAS FOR CONTINUED
OROGRAPHIC PRECIP IN A CONDITIONALLY UNSTABLE AND QUITE MOIST WEST
TO NORTHWEST FLOW ALOFT AS SUCH...THOUGH BULK OF ACTIVITY SHOULD
BE WANING DURING THE AFTERNOON HOURS. GFS HAS TRENDED TOWARDS THE
ECMWF/GEM OVER THE LAST 24 HOURS REGARDING THIS THUS CONFIDENCE
HAS INCREASED. SNOW LEVELS LOOK TO REMAIN NEAR 6000FT PER GUIDANCE
AND PRESENCE OF DEEP MOISTURE/MORE FAVORABLE FLOW WILL LIKELY
MAINTAIN AT LEAST SOME TRAVEL IMPACTS ABOVE THIS ELEVATION WED
MORNING.

FOCUS IN THE LONG TERM SHIFTS TO THE PLACEMENT/EVOLUTION OF THE NEXT
CLOSED LOW TO FORM OVER THE SOUTHEASTERN PACIFIC...AND ITS
INTERACTION W/THE STILL ELEVATED PW ACROSS THE EASTERN GREAT BASIN
AND ANY NORTHERN BRANCH ENERGY. THE DEVIL IS IN THE DETAILS
REGARDING THIS AND THE PLACEMENT OF THE ASSOCIATED DEFORMATION ZONE
ELONGATED TO THE NORTH AND EAST FROM ITS CENTER AS SUGGESTED IN MOST
GLOBAL GUIDANCE OUTPUT. BOTTOM LINE...CONFIDENCE IN DETAIL IS LOW
ATTM.

THE MORE INLAND PLACEMENT OF THE LOW CENTER DEPICTED BY THE
GFS...ESPECIALLY THE 18Z RUN...DRAPED A STRONGER MID LEVEL
DEFORMATION ACROSS NORTHERN/CENTRAL UTAH BEGINNING THU NIGHT AND
SOME ADDITIONAL INTERACTION W/A NORTHERN BRANCH SHORT WAVE. THE
ASSOCIATED QPF REFLECTED THAT AND APPEARED TO BE A HIGH END FORECAST
AND OUTLIER. SUBSEQUENT RUNS HAVE TRENDED A LITTLE FURTHER SOUTH
W/THE LOW CENTER...LESS NORTHERN BRANCH INFLUENCE AND QPF HAS
TRENDED MORE MODEST. THE ECMWF STILL DEPICTS A DEFORMATION FORMING
ACROSS NEARLY THE SAME AREA BUT A FURTHER SOUTH AND WEST PLACEMENT
OF THE LOW CENTER DIMINISHES LOCAL FORCING FURTHER WITH QPF
DECREASING AS SUCH. CONFIDENCE IN THE BIG PICTURE REGARDING THE
LARGE SCALE PATTERN IS QUITE HIGH REGARDING THIS LOW AND A
DEFORMATION ZONE DEVELOPING SOMEWHERE TO ITS NORTH AND EAST...BUT
ITS OVERALL SIGNIFICANCE LOCAL TO OUR AREA REMAINS TO BE SEEN.

REGARDING POPS FOR THIS PERIOD...FOCUSED ABOVE CLIMO POPS FROM
ROUGHLY SLC SOUTH THROUGH DELTA THU NIGHT WHERE GUIDANCE HAS MORE
OFTEN THAN NOT PLACED THE DEFORMATION. TRANSITIONED THIS ZONE SOUTH
FRI-SAT DUE TO FORCING DEPICTED TO BECOME MORE TIGHTLY BOUND TO THE
LOW CLOSING OFF MORE AGGRESSIVELY OVER THE BAJA REGION OVER TIME.

&&

.AVIATION...LOW CEILINGS WILL CONTINUE TO IMPACT THE KSLC TERMINAL
THIS MORNING WITH CIGS HOVERING BETWEEN 3-4000 FT AGL. ADDED SOLAR
INPUT COMBINED WITH A NET DRYING TREND SHOULD ALLOW THESE CIGS TO
SCATTER OUT BETWEEN 20-23Z THIS AFTERNOON BUT A 30 PERCENT CHANCE
EXISTS THAT LOW CIGS WILL REMAIN INTO THE EVENING HOURS. LIGHT AND
VARIABLE WINDS ARE EXPECTED TO BECOME A PREVAILING NORTHWEST BETWEEN
19-21Z...BUT SPEEDS WILL REMAIN NEAR OR BELOW 7 KNOTS.

&&

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

$$

SHORT TERM...ROGOWSKI
LONG TERM/AVIATION...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)



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.