Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 261155
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
455 AM MST THU FEB 26 2015

.SYNOPSIS...A WEATHER DISTURBANCE WILL TRACK SOUTHEAST ACROSS
UTAH TODAY. A DEVELOPING STORM SYSTEM WILL AFFECT MUCH OF THE
SOUTHERN AND CENTRAL GREAT BASIN THIS WEEKEND. A THIRD STORM
WILL IMPACT THE ENTIRE AREA THE FIRST HALF OF NEXT WEEK.

&&

.SHORT TERM (THROUGH 00Z MONDAY)...THE UPSTREAM SHORTWAVE EMBEDDED
WITHIN THE NORTHWEST FLOW ACROSS THE GREAT BASIN WILL REACH
NORTHERN UTAH THIS MORNING....THEN CONTINUE SOUTHEAST ACROSS THE
REST OF THE STATE BY EARLY THIS EVENING. WEAK BUT MOIST LOW-LEVEL
WARM ADVECTION UNDERNEATH MID-LEVEL COOLING SHOULD GENERATE
ENOUGH LIFT FOR LIGHT PRECIP AHEAD OF THE APPROACHING SHORTWAVE
THIS MORNING. PRECIP WILL EXPAND IN AREAL COVERAGE AND INTENSITY
LATE THIS MORNING AND AFTERNOON AS DEEP LAYER COLD ADVECTION SETS
IN AND DYNAMIC LIFT INCREASES WITH THE PASSING SHORTWAVE. LIGHT
SHOWERY PRECIP COULD PERSIST TONIGHT OVER/NEAR THE HIGHER TERRAIN
IN THE CYCLONIC...MOIST AND MARGINALLY UNSTABLE AIR MASS OVER
NORTHERN AND CENTRAL UTAH.

ATTENTION WILL TURN TO THE SHORTWAVE CURRENTLY OVER THE EASTERN
GULF OF ALASKA. THIS FEATURE WILL TURN SOUTHEAST ALONG THE
BRITCOL COAST LATER TODAY...THEN SETTLE SOUTH ALONG THE PACIFIC
NORTHWEST COAST LATE TONIGHT. AT THIS POINT THIS FEATURE WILL
SEPARATE FROM THE MAIN NORTHWEST FLOW AND DEVELOP INTO A CLOSED
LOW CENTERED OVER CENTRAL CALIFORNIA/WESTERN GREAT BASIN EARLY IN
THE UPCOMING WEEKEND.

THIS NEXT SYSTEM IN MANY RESPECTS WILL EVOLVE IN A SIMILAR MANNER
TO THE STORM THAT BROUGHT THE RECENT SIGNIFICANT SNOWFALL TO
SOUTHERN UTAH. A NEAR 700MB BAROCLINIC ZONE OVER SOUTHERN UTAH
FRIDAY WILL BECOME THE FOCUS FOR PRECIP AS A SOUTHWEST FLOW AHEAD
OF THE DEVELOPING LOW CREATES STRONG CONVERGENCE INTO THIS
BOUNDARY DURING THE DAY. SHORTWAVE ENERGY EJECTING OUT AHEAD OF
THE UPPER LOW ALONG WITH GOOD DIVERGENCE ALOFT NEAR THE ARIZONA
BORDER WILL CREATE GOOD SURFACE CYCLOGENESIS OVER SOUTHERN NEVADA
THROUGH SOUTHWEST UTAH WITH DEEP SYNOPTIC SCALE LIFT THROUGH
SATURDAY NIGHT.

AS THE WEEKEND PROGRESSES THE VARIOUS MODEL GUIDANCE TENDS TO
DIVERGE A BIT IN TERMS OF WHERE THE HEAVIEST PRECIP WILL EXIST.
ONE THING THAT DOES APPEAR SIMILAR BETWEEN THE VARIOUS MODELS IS
THE FRONTOGENESIS ACROSS ARIZONA AND INTO SOUTHWEST COLORADO. THIS
FRONTOGENETIC FORCING WILL REMAIN JUST OUTSIDE OF THE FORECAST
AREA...SUGGESTING THAT THE HEAVIER PRECIP MAY NOT PERSIST ACROSS
UTAH LATE IN THE WEEKEND. ONE CAVEAT TO THIS COULD BE ACROSS
CENTRAL AND NORTHEAST UTAH WHERE A BACKDOOR COLD FRONT COULD SERVE
AS THE FOCUS FOR MOISTURE CONVERGENCE AND FAIRLY STRONG LIFT LATE
IN THE WEEKEND.

NOT ANTICIPATING THE NEED FOR A WINTER STORM WATCH AT THIS
TIME...THOUGH SELECT WINTER WEATHER ADVISORIES MAY BECOME
NECESSARY AS THIS STORM EVOLVES AND THE IMPACTS AND EXPECTED
ACCUMULATIONS BECOME BETTER DEFINED.

&&

.LONG TERM (AFTER 00Z MONDAY)...THE TROUGH CENTERED OVER CALIFORNIA
IS PROGGED TO MOVE EAST INTO ARIZONA SUNDAY NIGHT/MONDAY. THIS WILL
SHIFT THE BEST MOISTURE AND INSTABILITY OVER THE FORECAST AREA INTO
SOUTHEAST UTAH AS PRECIPITATION DECREASES IN COVERAGE DURING THE DAY
MONDAY.

THE RELATIVE LULL IN PRECIPITATION WILL BE SHORT LIVED AS MODELS
INDICATE ANOTHER COLD STORM SYSTEM WILL DIVE DOWN INTO THE GREAT
BASIN ON THE HEELS OF THE PREVIOUS SYSTEM MONDAY NIGHT AND TUESDAY.
GFS INDICATES THIS TROUGH WILL FOLLOW A NEARLY IDENTICAL TRACK TO
THE WEEKEND SYSTEM WHILE STOPS THE INITIAL WAVE A LITTLE FARTHER
NORTH...OVER NEVADA INSTEAD OF SOUTHERN CALIFORNIA. BOTH SOLUTIONS
WILL COOL THE AIRMASS OVER THE FORECAST AREA SIGNIFICANTLY AND
PROVIDE A GOOD AMOUNT OF MOISTURE AND INSTABILITY. THESE SOLUTIONS
WOULD RESULT IN FAIRLY WIDESPREAD SNOW ON TUESDAY...AND GOING POPS
INDICATE THIS WELL.

THE BACK END OF THE SYSTEM IS EXPECTED TO TRACK DOWN TUESDAY
AFTERNOON AND EVENING...TRACKING ACROSS UTAH EARLY WEDNESDAY.
GUIDANCE SHOWS FAST DRYING FOR MUCH OF UTAH AND SOUTHWEST WYOMING
WEDNESDAY AFTERNOON AND EVENING BEHIND THE EXITING TROUGH...WITH
HIGH PRESSURE RETURNING FOR DAY 7.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED AT THE SLC TERMINAL DURING
THE MORNING. CIGS ARE EXPECTED TO LOWER TO OR BELOW 6000 FT AGL
BETWEEN 14Z AND 16Z AS RAIN AND SNOW DEVELOPS IN THE VICINITY OF THE
TERMINAL. CONDITIONS MAY DROP INTO THE MVFR RANGE AT TIMES DURING
THE EARLY AFTERNOON AS THE PRECIPITATION BECOMES MORE WIDESPREAD.
LIGHT SOUTHEAST WINDS ARE EXPECTED TO SHIFT TO THE NORTHWEST BETWEEN
17Z AND 19Z.

&&

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

$$

SHORT TERM...CONGER
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)


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