Heavy Snow Warning 4, NWS Salt Lake City, UT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
309 AM MST TUE JAN 29 2008

.SYNOPSIS...AN ACTIVE WEATHER PATTERN WILL CONTINUE THROUGH THIS
WEEKEND AS A SERIES OF STORMS MOVE THROUGH THE GREAT BASIN. THE NEXT
STORM WILL SPREAD ACROSS THE AREA LATE TODAY AND LAST INTO
WEDNESDAY. ANOTHER STORM WILL ARRIVE THURSDAY NIGHT.

&&

.DISCUSSION...SNOWY PATTERN FOR NORTHERN UTAH WITH SHORT
WAVE TROUGH TONIGHT AND AGAIN THURSDAY NIGHT INTO FRIDAY.
INSTABILITY DEPTH DECREASING QUICKLY BUT LIGHT SNOW SHOWERS
PERSISTING ALONG THE SPINE OF UTAH MTNS WITH STRONG WINDS
ACROSS THE RIDGES. NEXT SYSTEM WILL BEGIN WILL BACK THE
FLOW AND INCREASE SOUTHERLIES THIS AFTERNOON...WITH WARM
AIR ADVECTION SNOW SPREADING INTO FAR NORTHERN UTAH.

HAVE UPGRADED MOST WATCHES TO WARNINGS WITH SURROUNDING SNOW
ADVISORIES...MAIN EVENT 02Z TO 15Z WEDNESDAY. WARM AIR ADVECTION
THIS EVENING AND SOUTHERLY FLOW WILL BE TOPPED BY COLD AIR
ADVECTION AND FALLING HEIGHTS. THIS WILL INCREASE SNOW COVERAGE
AND INTENSITY WITH MODERATE SOUTHWEST FLOW ENHANCING PRECIP IN THE
WASATCH FRONT BENCHES AND WASATCH BACK...AS SNOW SPREADS AS FAR
SOUTH AS THE SANPETE VALLEY AND WASATCH PLATEAU. DIRECT HIT WITH
COLD AIR ALOFT FROM 06 TO 12Z TONIGHT WITH LOW TO MID LEVEL COLD
FRONTAL PASSAGE BETWEEN 09 AND 12Z TONIGHT IN NORTHERN...
QUICKLY SPREADING SOUTH DOWN THE I-15 CORRIDOR EARLY WEDNESDAY
MORNING. UPPER TROUGH PROGGED TO DIG ACROSS EASTERN UTAH ON
WEDNESDAY WITH POST FRONTAL COLD UNSTABLE NORTHWEST FLOW
REDEVELOPING SNOW SHOWERS...ESPECIALLY I-15 BELT AND SPINE OF UTAH
WITH DOWNSLOPE DEVELOPING IN EASTERN AREAS AND DESERTS. FRONTAL
BOUNDARY NOT AS STRONG BUT SYSTEM AS COLD/UNSTABLE AS LAST WAVE WITH
EFFECTIVE COLD PREFRONTAL SNOW IN THE NORTH BENCHES AND MOUNTAINS.
COLD FRONTAL BAND SHOULD HAVE A BURST OF HEAVY SNOW AND BREEZY.

CLEARING WEDNESDAY NIGHT AND COLD WITH -18 TO -19C 700 MB AIR
ACROSS NORTHERN UTAH AND STABILIZING AFTER 03Z THURSDAY. WARM AIR
ADVECTION PROGGED TO REDEVELOP THURSDAY AFTERNOON ACROSS THE NORTH
AGAIN. NAM...GFS AND ECMWF CONTINUE TO BE FLATTER WITH LESS
DIGGING OF THIS SHORT WAVE TROUGH BUT A MOIST PROLONGED PERIOD OF
DEEP LIFT IN W-SW FLOW THURSDAY NIGHT. THIS SAGS A WEST TO EAST
BAROCLINIC ZONE ACROSS NORTHERN UTAH AND INTO CENTRAL UTAH FRIDAY
MORNING. SHOULD BE WARNING LEVEL SNOW FOR FAR NORTHERN VALLEYS
NORTH OF SLC AND FOR THE WASATCH RANGE AND MOUNTAIN VALLEYS.
FRONTAL BOUNDARY DROPS INTO SOUTHERN UTAH ON FRIDAY BUT BEGINS TO
LACK UPPER SUPPORT SO IT GRADUALLY WEAKENS. WARM AIR ADVECTION
THEN DEVELOPS FRIDAY NIGHT INTO SATURDAY WITHIN SHORT WAVE WEAK
RIDGING ALOFT. NEXT WAVE FORECAST BY ECMWF AND GFS FOR SATURDAY
NIGHT WITH GFS STRONGER WITH A SOLID COLD FRONT ACROSS UTAH FOR
SUNDAY...SIMILAR ON ECMWF BUT WEAKER AS THIS MODEL BRINGS THE
FIRST WAVE SATURDAY NIGHT AND THEN A SHARP UPPER TROUGH SUNDAY
NIGHT INTO MONDAY. MEAN UPPER TROUGH CARVING ACROSS THE GREAT
BASIN IS THE IDEA WITH POSSIBLE ENHANCEMENT OF THE FRONT SATURDAY
NIGHT INTO SUNDAY AND AGAIN 12Z MONDAY. HAVE INCREASED WEATHER
STARTING SATURDAY NIGHT. SHORT WAVE RIDGE PROGGED FOR TUESDAY WITH
YET ANOTHER WAVE APPROACHING. CONSIDERABLE BUT REASONABLE GFS
ENSEMBLE SPREAD SUNDAY INTO MONDAY.

&&

.AVIATION...WEST WINDS AT THE SLC TERMINAL ARE EXPECTED TO SHIFT TO
THE SOUTH BY ABOUT 12Z. AFTER THE SHIFT OCCURS...WINDS SHOULD REMAIN
SOUTHERLY AND GRADUALLY INCREASE THROUGHOUT THE DAY.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...HEAVY SNOW WARNING FROM 3 PM TUESDAY TO NOON WEDNESDAY FOR
     UTZ001-UTZ002-UTZ006.

     WINTER STORM WARNING FROM 5 PM TUESDAY TO 4 PM WEDNESDAY FOR
     UTZ008-UTZ009-UTZ010.

     WINTER STORM WARNING FROM 4 PM TUESDAY TO 4 PM WEDNESDAY FOR
     UTZ007.

     WINTER STORM WARNING FROM 6 PM TUESDAY TO 4 PM WEDNESDAY FOR
     UTZ003-UTZ004-UTZ014.

     SNOW AND BLOWING SNOW ADVISORY FROM 6 PM TUESDAY TO 4 PM
     WEDNESDAY FOR UTZ005-UTZ011-UTZ012-UTZ015.

WY...SNOW AND BLOWING SNOW ADVISORY FROM 6 PM TUESDAY TO 4 PM
     WEDNESDAY FOR WYZ021.

&&

PUBLIC...TARDY
AVIATION...TRAHAGAN

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
430 PM MST MON JAN 28 2008

UTZ001>016-019>021-517-518-WYZ021-291300-
CACHE VALLEY/UTAH PORTION-NORTHERN WASATCH FRONT-
SALT LAKE AND TOOELE VALLEYS-SOUTHERN WASATCH FRONT-
GREAT SALT LAKE DESERT AND MOUNTAINS-WASATCH MOUNTAIN VALLEYS-
WASATCH MOUNTAINS I-80 NORTH-WASATCH MOUNTAINS SOUTH OF I-80-
WESTERN UINTA MOUNTAINS-WASATCH PLATEAU/BOOK CLIFFS-
WESTERN UINTA BASIN-CASTLE COUNTRY-SAN RAFAEL SWELL-
SANPETE/SEVIER VALLEYS-WEST CENTRAL UTAH-SOUTHWEST UTAH-
UTAHS DIXIE AND ZION NATIONAL PARK-SOUTH CENTRAL UTAH-
GLEN CANYON RECREATION AREA/LAKE POWELL-CENTRAL MOUNTAINS-
SOUTHERN MOUNTAINS-SOUTHWEST WYOMING-
430 PM MST MON JAN 28 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN TWO THIRDS OF
UTAH AND SOUTHWEST WYOMING.

.DAY ONE...TONIGHT

A STRONG COLD FRONT IS MOVING EAST ACROSS EASTERN UTAH THIS EVENING
WITH AREAS OF RAIN AND SNOW AND ISOLATED THUNDERSTORMS. SNOW SHOWERS
WILL CONTINUE OVERNIGHT FOR THE I-15 CORRIDOR FROM CEDAR CITY TO
TREMONTON.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

AN ACTIVE WEATHER PATTERN WILL EXIST ACROSS THE ENTIRE AREA
THROUGH SUNDAY. THE NEXT STORM SYSTEM WILL REACH UTAH TUESDAY
NIGHT...FOLLOWED BY ANOTHER ENERGETIC STORM FRIDAY. BOTH OF THESE
STORMS HAVE THE POTENTIAL TO PRODUCE SIGNIFICANT SNOWFALL OVER THE
MOUNTAINS AND ADJACENT VALLEYS...ESPECIALLY ACROSS THE NORTHERN
HALF OF THE STATE.

ANOTHER STORM COULD REACH UTAH BY LATE SUNDAY...THOUGH THE MAIN
PORTION OF THIS STORM WILL PROBABLY HOLD OFF UNTIL EARLY NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

GIBSON