Area Forecast Discussion
Issued by NWS Salt Lake City, UT

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 311043
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
343 AM MST SUN JAN 31 2016

.SYNOPSIS...A WINTER STORM WILL AFFECT MOSTLY SOUTHERN AND CENTRAL
UTAH THROUGH MONDAY NIGHT...BRINGING SIGNIFICANT SNOW
ACCUMULATIONS AND GUSTY WINDS. COLD NORTHERLY FLOW WILL FOLLOW
ACROSS THE REGION FOR THE MIDDLE PORTION OF NEXT WEEK.

&&

.SHORT TERM (THROUGH 00Z WEDNESDAY)...
WATER VAPOR LOOP SHOWS A COLD TROUGH NEARING THE WEST COAST.
AMDAR 400-250MB WIND OBSERVATIONS SHOW A 100-155KT NORTHWESTERLY
JET FROM THE EASTERN PACIFIC INTO THE SOUTHWEST CONUS.
GOES/HRRR/GPS/00Z SLC RAOB INDICATE THE PRECIPITABLE WATER VALUE
RANGES BETWEEN 0.05"- 0.15" NORTHERN MOUNTAINS...TO 0.30"-0.60"
SOUTHERN VALLEYS.

ADDED MENTION OF AREAS OF FOG NORTH OF SLC DUE TO PARTIAL CLEARING
AND SATURATED CONDITIONS.

RAP 850-700MB THICKNESS/SATURATED EQUIVALENT POTENTIAL
TEMPERATURE/STREAMLINES INDICATE STALLED FRONTAL BOUNDARY ACROSS THE
ARIZONA BORDER WILL LIFT INTO SOUTHERN UTAH TODAY.

COLD CLOSED LOW OVER THE EASTERN PACIFIC WILL INTERACT WITH THE
ATMOSPHERIC RIVER TO CREATE A WINTER STORM FOR THE SOUTHWEST CONUS
TODAY...CONTINUING ACROSS SOUTHERN AND CENTRAL UTAH SUNDAY NIGHT AND
MONDAY. THERE CONTINUES TO BE HIGH CONFIDENCE IN THIS EVOLUTION. THE
ANOMALOUS MOISTURE LEVELS AND WARM ADVECTION WILL LEAD TO NO BREAK
FOR PORTIONS OF SOUTHERN UTAH. HAVE BEGUN THE WINTER STORM WARNINGS
FOR SOUTHWEST UTAH AND THE SOUTHERN MOUNTAINS WITH THE MORNING
PACKAGE.

STORM SYSTEM WILL OFFER UP SIGNIFICANT DYNAMICAL SUPPORT IN THE FORM
OF VERTICAL MOTION OFFERED FROM THE LEFT EXIT REGION OF A STRONG
PACIFIC JET...DIFFLUENCE ALOFT...PVA...AND ISENTROPIC LIFT ALONG THE
FRONTAL SLOPE.

DIXIE CONTINUES TO BE A CONCERN FOR WINTER IMPACTS AS WELL. WHILE
FORECAST SOUNDINGS INDICATE ST GEORGE MAY NOT CHANGE OVER TO SNOW
UNTIL EARLY MONDAY MORNING...PRECIPITATION RATES WILL LIKELY SUPPORT
CHANGING OVER TO SNOW EARLIER THAN ENVIRONMENTAL TEMPERATURES
SUGGEST. ADDITIONALLY...HIGHER ELEVATIONS OF DIXIE SUCH AS NEAR
IVINS/TOQUERVILLE/ZION NATIONAL PARK WILL BE ALL SNOW FOR MUCH OF
THIS STORM BEGINNING THIS EVENING.

LOCAL WRF MODEL CONTINUES TO INDICATE A MOIST EASTERLY FLOW FOR THE
WESTERN UINTA BASIN BEGINNING THIS AFTERNOON AND MAXIMIZING TONIGHT
INTO TOMORROW...WITH SYNOPTIC SCALE WRAP AROUND EXPECTED MONDAY
AFTERNOON AND EVENING. AN ADVISORY MAY BE NEEDED BY THE AFTERNOON
PACKAGE.

SPEAKING OF MOIST EASTERLY UPSLOPE...LOCAL WRF BASED ON NAM HAS BEEN
CONSISTENT NOW FOR MULTIPLE RUNS DEPICTED HIGH QPF IN SOUTHWEST
WYOMING MONDAY THROUGH TUESDAY. HAVE ISSUED A WINTER STORM WATCH
WITH CURRENT INDICATIONS OF 4-8" I-80 CORRIDOR TO MORE THAN A FOOT
POSSIBLE ON THE NORTHERN SLOPES OF THE UINTA MOUNTAINS.

NORTHERLY WINDS BECOME BREEZY ACROSS THE WESTERN VALLEYS MONDAY ON
THE BACK SIDE OF THE STORM SYSTEM...CONTINUING ACROSS EAST CENTRAL
UTAH FROM THE NORTHWEST TUESDAY. WIND ADVISORIES MAY BECOME NECESSARY
IN SOME AREAS...WHILE BLOWING AND DRIFTING SNOW CREATE REDUCTION OF
VISIBILITIES AND ADDITIONAL ROAD SNOW POTENTIAL.

.LONG TERM (AFTER 00Z WEDNESDAY)...
LINGERING SHORTWAVE ENERGY ON THE BACK SIDE OF THE EXITING TROUGH
WILL KEEP MOISTURE AND INSTABILITY OVER NORTHERN AND CENTRAL UTAH
THROUGH WEDNESDAY. THIS WILL RESULT IN AN OUTSIDE SHOT OF SNOW
SHOWERS...PRIMARILY OVER THE HIGHER TERRAIN.

GLOBAL MODELS INDICATE HIGH PRESSURE WILL BRIEFLY MOVE BACK OVER THE
AREA BRIEFLY WEDNESDAY NIGHT/EARLY THURSDAY...BUT A PACIFIC
NORTHWEST SHORTWAVE IS EXPECTED TO BREAK DOWN THE RIDGE AS IT PASSES
THURSDAY AFTERNOON THROUGH FRIDAY MORNING. THOUGH EC/GFS APPEAR TO
BE CONVERGING ON A SOLUTION WHERE THIS TROUGH IMPACTS NORTHERN
PORTIONS OF THE FORECAST AREA...IT IS MUCH MORE OF A GRAZING SYSTEM
IN THE LATEST ECMWF. 00Z AND 06Z GFS SOLUTIONS THEREFORE BRING IN A
MORE SUBSTANTIAL SHOT OF COLD AIR WITH THE ASSOCIATED FRONT ALONG
WITH BETTER OVERALL MOISTURE AND INSTABILITY. HAVE RAISED POPS
DURING THIS TIME TO ACCOUNT FOR THE CONVERGING SOLUTIONS.

HIGH PRESSURE IS THEN PROGGED TO RETURN FOR LATE FRIDAY INTO
SATURDAY WITH MODELS INDICATING ANOTHER PACIFIC NORTHWEST SYSTEM
MOVING THROUGH ALL OF UTAH AND SOUTHWEST WYOMING SUNDAY AFTERNOON
INTO MONDAY.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE DAY AT THE
SLC TERMINAL WITH ANY CIGS ABOVE 6000 FT AGL. THERE IS A 30 PERCENT
CHANCE THAT FOG IN THE VICINITY OF THE TERMINAL COULD RESULT IN
BRIEF MVFR OR IFR CONDITIONS BEFORE 15Z. SOUTHEAST WINDS ARE
EXPECTED TO SHIFT TO THE NORTHWEST BETWEEN 18Z AND 20Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING FROM 11 AM THIS MORNING TO 11 PM MST MONDAY
     FOR UTZ012>015-020-021.

     WINTER STORM WARNING UNTIL 11 PM MST MONDAY FOR UTZ016-517-518.

     WINTER WEATHER ADVISORY FROM 11 AM THIS MORNING TO 11 PM MST
     MONDAY FOR UTZ010-019.

WY...WINTER STORM WATCH FROM MONDAY MORNING THROUGH LATE MONDAY NIGHT
     FOR WYZ021.

&&

$$

SHORT TERM...ROGOWSKI
LONG TERM/AVIATION...TRAPHAGAN

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.