Severe Thunderstorm Warning 1, NWS Salt Lake City, UT

000 
WWUS55 KSLC 032331
SVSSLC

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
531 PM MDT SUN MAY 3 2009

UTC011-035-045-032340-
/O.CAN.KSLC.SV.W.0001.000000T0000Z-090503T2345Z/
SALT LAKE UT-TOOELE UT-DAVIS UT-
531 PM MDT SUN MAY 3 2009

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN DAVIS...
NORTHEASTERN TOOELE AND NORTHWESTERN SALT LAKE COUNTIES IS
CANCELLED...

THE STORM HAS WEAKENED AND IS NO LONGER SEVERE. THEREFORE THE WARNING
HAS BEEN CANCELLED. WINDS GUSTING OVER 40 MPH ARE STILL POSSIBLE.

LAT...LON 4103 11208 4061 11200 4060 11253 4098 11257
TIME...MOT...LOC 2330Z 265DEG 29KT 4079 11221

$$

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
234 PM MDT SUN MAY 3 2009

.SYNOPSIS...A SERIES OF WEAK PACIFIC WEATHER SYSTEMS WILL CROSS
NORTHERN UTAH THROUGH TUESDAY NIGHT. A MILD WESTERLY FLOW ALOFT
WILL FOLLOW FOR THE LATTER HALF OF THE WEEK.

&&

.DISCUSSION...WATER VAPOR LOOP SHOWS A SERIES OF WAVES ROTATING
AROUND AN UPPER LOW OFF OF BRITISH COLUMBIA. STRONG WESTERLIES WERE
IN PLACE ALONG 40N...SHEARING ENERGY EASTWARD. ONE SUCH WAVE IS
CURRENTLY OVER NORTHERN CALIFORNIA. ACARS 400-250MB WIND
OBSERVATIONS REVEAL A WESTERLY JET OF 100-130KT CROSSING INTO
NORTHERN CALIFORNIA FROM THE PACIFIC. 12Z 700MB ANALYSIS SHOWS
RIDGING IN PLACE ACROSS THE GREAT BASIN AHEAD OF A COLD FRONT
CROSSING THE PACIFIC NORTHWEST. COOL ADVECTION WAS OCCURRING LOCALLY
WITH -1C AT KSLC AND -2C UPSTREAM AT KLKN.

12Z KSLC RAOB INDICATES 1 TO 3C OF COOLING THROUGH THE COLUMN DURING
THE PAST 24 HOURS. THE PRECIPITABLE WATER VALUE REMAINS ABOVE A HALF
INCH.

THE COMBINATION OF INCREASED SOLAR INSOLATION THIS AFTERNOON AND
COOLING ALOFT WILL STEEPEN LAPSE RATES...WITH THE 09Z SHORT RANGE
ENSEMBLES INDICATING A GOOD CHANCE OF 7-8C 500-700MB LAPSE RATES
DEVELOPING THIS AFTERNOON. SAME GUIDANCE INDICATES 250 J/KG OF
MUCAPE WILL BE LIKELY THIS AFTERNOON ACROSS NORTHERN
UTAH...COINCIDENT WITH INCREASING CHANCES OF 30-40KTS OF EFFECTIVE
SHEAR WITH THE ARRIVAL OF THE EXIT REGION OF THE UPPER LEVEL JET.
THE RUC AND GOES SOUNDER INDICATE LIFTED INDICES HAVE DECREASED TO
-2 TO -6C ACROSS THE NORTHWEST FORECAST AREA AS OF 20Z. EXPECT
SCATTERED CONVECTION ACROSS NORTHERN UTAH AND ISOLATED CONVECTION
ACROSS PARTS OF SOUTHERN UTAH TO CONTINUE TO DEVELOP MID AFTERNOON
AND LAST INTO THE EARLY EVENING HOURS. THE 00Z WRF-NMM RUN FOR SPC
AND 06Z NCEP WRF-NMM/ARM SIMULATED REFLECTIVITY ALL INDICATE THIS
SCENARIO UNFOLDING TO SOME DEGREE.

CONVECTION WILL HAVE TO BE MONITORED THROUGHOUT THE LATE AFTERNOON
AND EVENING FOR STRONG TO LOCALLY SEVERE THUNDERSTORMS GIVEN THE
DEGREE OF DEEP LAYER SHEAR AND INVERTED-V PROFILES INDICATED BY
THE 12Z NAM.

CONVECTION WILL TEND TO STRATIFY DURING THE LATER EVENING HOURS
ACROSS NORTHERN AND CENTRAL UTAH BEFORE PASSING TO THE EAST AND
DISSIPATING OVERNIGHT. SNOW LEVELS RISE TO ABOUT 9500-11000 FEET
BY EVENING BEFORE LOWERING TO 8000-10000 FEET LATE TONIGHT.

SHORT WAVE RIDGING TAKES PLACE TOMORROW WITH PERHAPS SOME LINGERING
SHOWERS IN THE MOUNTAINS. EXPECTING SLIGHTLY COOLER CONDITIONS
TOMORROW WITH THE COLD FRONTAL PASSAGE WHICH TAKES PLACE TONIGHT.

WARM ADVECTION INCREASES MONDAY NIGHT AHEAD OF ANOTHER STRONG
WESTERLY JET NOSING IN FROM THE PACIFIC TUESDAY. THIS SHOULD
INCREASE THE CHANCES OF ANOTHER HEALTHY SPRING PRECIPITATION EVENT
ACROSS THE NORTHERN FORECAST AREA. RISING HEIGHTS BEHIND THE SHORTWAVE
ENERGY SHOULD ALLOW HEIGHTS TO GRADUALLY RISE DURING THE MID
WEEK...PLACING PRECIPITATION NORTH OF THE IDAHO BORDER.

BOTH THE 12Z GFS AND EUROPEAN ADVERTISE ANOTHER DISTURBANCE ARRIVES
ACROSS THE GREAT BASIN ON THE STRONG WESTERLIES SOMETIME NEXT
WEEKEND. WITH TIMING DIFFERENCES BETWEEN THE TWO PIECES OF GUIDANCE
DUE TO THE STRONG FLOW...HAVE SIDED SLIGHTLY SLOWER WITH THE
EUROPEAN FOR NOW.

&&

.AVIATION...RAIN SHOWERS AND PERHAPS A THUNDERSTORM WILL MOVE ACROSS
THE AREA LATER THIS AFTERNOON AHEAD OF A COLD FRONT. HIGH END MVFR
CONDITIONS CAN NOT BE RULED OUT WITH THIS BAND. THE COLD FRONT IS
EXPECTED TO CROSS THE TERMINAL BETWEEN 23-01Z THIS EVENING.

&&

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

&&

PUBLIC...ROGOWSKI
AVIATION...KRUSE

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
236 PM MDT SUN MAY 3 2009

UTZ001>016-019>021-517-518-WYZ021-041200-
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-
236 PM MDT SUN MAY 3 2009

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM AHEAD
OF AN APPROACHING COLD FRONT DURING THE MID AFTERNOON...LASTING
INTO THE EVENING HOURS. SOME OF THESE STORMS MAY BECOME STRONG OR
LOCALLY SEVERE WITH THE THREAT OF DAMAGING WINDS AND LARGE HAIL AS
WELL AS DANGEROUS CLOUD TO GROUND LIGHTNING AND A BRIEF HEAVY
DOWNPOUR.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SUNDAY

A WARM AND GENERALLY DRY WESTERLY FLOW ALOFT WILL EXIST ACROSS
THE AREA THROUGH FRIDAY.

SOUTHWEST WINDS MAY BECOME GUSTY ACROSS PORTIONS OF SOUTHERN AND
CENTRAL UTAH NEXT WEEKEND AS THE NEXT STORM SYSTEM APPROACHES.
THESE WINDS MAY BE STRONG ENOUGH TO AFFECT WIND SENSITIVE
OPERATIONS.

.SPOTTER INFORMATION STATEMENT...

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

ROGOWSKI

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