Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 292147
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
347 PM MDT SUN MAR 29 2015

.SYNOPSIS...A WEAK WEATHER DISTURBANCE WILL MOVE EAST INTO
NORTHWEST ARIZONA LATE MONDAY. HIGH PRESSURE ALOFT WILL RETURN TO
THE AREA EARLY IN THE WEEK...FOLLOWED BY A SERIES OF COLD PACIFIC
WEATHER DISTURBANCES FOR THE LATTER HALF OF THE WORK WEEK.

&&

.SHORT TERM (THROUGH 00Z THURSDAY)...CONVECTION HAS FIRED UP OVER
THE SOUTHERN MOUNTAINS NORTH OF THE OLD SURFACE BOUNDARY AT MID-
AFTERNOON. THIS CONVECTION APPEARS TO BE ALIGNED WITH A WEAK NEAR
700MB CONVERGENCE ZONE AND SUPPLEMENTED BY DIFFERENTIAL HEATING
OVER THE HIGHER TERRAIN. THIS CONVECTIVE ACTIVITY WILL LIKELY
PERSIST OR EVEN INCREASE SLIGHTLY THROUGH THE BALANCE OF THE
AFTERNOON...THEN DECREASE WITH THE LOSS OF HEATING AND THE
DISSIPATION OF THE CONVERGENCE ALOFT.

THE VORTICITY MAX HUNG UP OVER THE CENTRAL SIERRAS STILL PROGGED
TO DRIFT EAST-SOUTHEAST INTO SOUTHERN NEVADA MONDAY...THEN TRACK
EAST INTO NORTHWEST ARIZONA MONDAY EVENING. THIS FEATURE WILL
LIKELY WEAKEN AS IT ENTERS ARIZONA WITH ONLY A MINIMAL IMPACT ON
CONVECTION ACROSS THE SOUTH DURING THE LATE AFTERNOON AND EVENING.

A LOW AMPLITUDE RIDGE WILL MOVE WEST TO EAST ACROSS THE GREAT
BASIN MONDAY NIGHT THROUGH EARLY TUESDAY. ONCE THIS FEATURE CLEARS
UTAH LOOK FOR AN INCREASINGLY WARM SOUTHWEST FLOW TO DEVELOP AHEAD
OF A SERIES OF COLD PACIFIC TROUGHS MOVING INTO THE BASIN FOR THE
LATTER HALF OF THE WEEK. VERY WARM AND WINDY CONDITIONS WILL EXIST
TUESDAY AFTERNOON AHEAD OF THE LEADING COLD FRONT SCHEDULED TO
REACH NORTHWEST UTAH TUESDAY AFTERNOON. VERY WARM TEMPS AHEAD OF
THE FRONT ALONG WITH RATHER COLD AIR TRAILING THE FRONT WILL LEAD
TO A SIGNIFICANT INCREASE IN THE PRESSURE GRADIENT ACROSS EASTERN
NEVADA AND WESTERN UTAH DURING THE AFTERNOON. STRONG WINDS WILL
DEVELOP WITH THE POSSIBILITY OF WIND RELATED HAZARDS ACROSS
WESTERN UTAH DURING THE LATE AFTERNOON AND EARLY EVENING HOURS.
CONVECTION WILL LIKELY HOLD OFF UNTIL TUESDAY EVENING WHEN THE
MID-LEVEL COLD AIR AND DYNAMIC SUPPORT FOR LIFT REACHES NORTHWEST
UTAH.

THE SECOND AND SIGNIFICANTLY COLDER SECONDARY TROUGH WILL REACH
THE WESTERN GREAT BASIN LATE WEDNESDAY. THIS FEATURE WILL LIKELY
CARVE OUT A BROAD COLD TROUGH ACROSS MUCH OF THE BASIN HEADING
INTO THE EXTENDED PERIOD OF THE CURRENT FORECAST PACKAGE.

&&

.LONG TERM (AFTER 00Z THURSDAY)...AFTER THE INITIAL COLD FRONTAL
PUSH ON WEDNESDAY...THE COLDER LOW LEVEL AIR WILL LINGER ACROSS THE
NORTHERN TWO THIRDS OF THE CWA WEDNESDAY NIGHT...BEFORE A STRONGER
AND DEEPER SYSTEM MOVES OVER UTAH THURSDAY. THE SOUTHERN TIER OF THE
CWA WILL LIKELY SEE MODERATE TO STRONG WINDS THURSDAY AS 700MB WINDS
INCREASE TO 35-45 KTS ALONG WITH A FAVORABLE WEST TO EAST SURFACE
GRADIENT. DEPENDING ON FUEL STATUS THIS MAY BECOME THE FIRST RED
FLAG WARNING DAY OF THE SEASON. IN ADDITION THE EC IS FASTER THAN
THE GFS AND IF THIS SOLUTION COMES TO BE THEN THE WINDS WILL NOT BE
AS STRONG EITHER. THE GFS HAS BEEN MORE CONSISTENT SO LEANED IN THAT
DIRECTION.

DUE TO THE GFS BEING SLOWER AND DEEPER IT HAS A BETTER ORGANIZED
BAROCLINIC ZONE FARTHER NORTH STRETCHING FROM ABOUT SLC SOUTHWARD
TO CEDAR CITY. HAVE INCREASED POPS SOME TO ACCOMMODATE THIS SOLUTION.
WITH TEMPERATURES DOWN TO -10 DEGREES C AT 700MB FROM ABOUT NEPHI
NORTHWARD HAD TO GO WITH ALL SNOW IN THE FORECAST FOR VALLEYS AND A
MIXTURE OF RAIN AND SNOW OVER THE WESTERN VALLEYS SOUTH OF THERE.
AMOUNTS DO NOT LOOK TO BE SIGNIFICANT AS DYNAMICS ALOFT ARE NOT
COHESIVE. TEMPERATURES WILL BE BELOW NORMAL FOR THE FIRST TIME IN
ALONG TIME SO THEY MAY FEEL COLDER THAN OTHERWISE FOR THE END OF
MARCH.

THE SYSTEM PULLS OUT RAPIDLY FRIDAY BUT STILL COULD SEE SOME SHOWERS
OVER THE HIGHER TERRAIN OF NORTHERN UTAH INTO FRIDAY AFTERNOON AS A
FINAL WEAK WAVE CLIPS THE CWA. THE 700MB TEMPS REMAIN QUITE COLD AT
MINUS 10 DEGREES C THROUGH NOON FRIDAY SO DON`T EXPECT MUCH
WARMING YET ON FRIDAY. TEMPERATURES WARM ANOTHER 4 TO 6 DEGREES C
AT 700MB SATURDAY SO TEMPERATURES WILL CLIMB ABOVE NORMAL ONCE
AGAIN BY SATURDAY.

ANOTHER SYSTEM APPROACHES ON SUNDAY BUT IT APPEARS TO BE TRENDING A
LITTLE SLOWER SO HAVE BACKED OFF ON THE POPS FOR NORTHERN UTAH FOR
SUNDAY. SOUTH WINDS WILL HELP GET THE TEMPS BACK INTO THE 60S SUNDAY
OVER MOST VALLEYS BEFORE THE NEXT COLD FRONT.


&&

.AVIATION...THE ONLY OPERATIONAL WEATHER CONCERN AT THE SLC TERMINAL
IS THE SURFACE WIND FORECAST. WINDS ARE EXPECTED TO BE LIGHT
NORTHWEST THROUGH 03Z THEN SHIFT TO SOUTHEAST ABOUT 03Z.

&&

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

$$

SHORT TERM...CONGER
LONG TERM/AVIATION...STRUTHWOLF

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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