HAMweather.com Area Forecast Discussion for County Warning Area SLC

Thu, 16 Feb 2012 12:06:00 GMT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
500 AM MST THU FEB 16 2012

.SYNOPSIS...WEAK HIGH PRESSURE WILL RETURN TO THE REGION
TODAY...FOLLOWED BY A WEAK SYSTEM EXPECTED TO CLIP NORTHERN UTAH
FRIDAY. THE NEXT WINTER STORM MAY AFFECT THE AREA LATE SATURDAY
NIGHT INTO MONDAY.

.DISCUSSION...WATER VAPOR LOOP SHOWS THE UPPER LOW DIVING SOUTH INTO 
NORTHERN MEXICO...WITH THE MID LEVEL DEFORMATION ZONE ACROSS CENTRAL 
UTAH.

CANCELLED THE ADVISORIES FOR PORTIONS OF CENTRAL AND SOUTHERN UTAH. 
AS THE STORM CONTINUES TO PULL SOUTH FROM THE AREA...DYNAMIC LIFT IS 
WANING RESULTING IN WARMING CLOUD TOPS AND A DECREASE IN COVERAGE 
WITH LOWER RATES.

FOG IS ON THE MIND THIS MORNING AS THE MOIST SYSTEM PULLS SOUTH. THE 
EXTENSIVE CLOUD COVER ACROSS SOUTHERN UTAH AND PRESSURE GRADIENT 
ACROSS NORTHERN UTAH IS HELPING TO KEEP FOG COVERAGE FROM BECOMING 
MORE THAN PATCHY. BEST CHANCE FOR FOG IS ACROSS THE WASATCH 
BACK..SOUTHWEST WYOMING...UTAH COUNTY...AND AREAS THAT START TO 
CLEAR ACROSS CENTRAL AND SOUTHERN UTAH.

THE AFOREMENTIONED PRESSURE GRADIENT IS SUPPORTING GUSTS OF 20-30 
MPH ACROSS THE WEST DESERTS. AS THE GRADIENT DEVELOPS FURTHER 
SOUTH...LOCAL WRF-ARW4G INDICATES GUSTS ACROSS FAVORED PORTIONS OF 
WASHINGTON COUNTY WILL INCREASE BUT REMAIN BELOW ADVISORY CRITERIA 
OF 45 MPH TODAY.

A NORTHERN STREAM SYSTEM MAY GRAZE NORTHERN UTAH AND SOUTHWEST 
WYOMING HEADING INTO THE WEEKEND. RETAINED SLIGHT CHANCE POPS FOR 
NEARBY HIGHER TERRAIN WITH COLD ADVECTION ACROSS THE AREA.

GFS/EUROPEAN INDICATE A POTENTIAL PRESIDENTS DAY WEEKEND WINTER 
STORM FOR MUCH OF UTAH AND SOUTHWEST WYOMING. THE TIMING OF THE COLD 
FRONT HAS SLOWED DOWN UNTIL LATER SATURDAY NIGHT AND 
SUNDAY...FOLLOWED BY CYCLOGENESIS ACROSS COLORADO MONDAY. GIVEN 
CONTINUED CONSISTENCY OF THE MODELS...HAVE BUMPED UP POPS FURTHER. 
WITH THIS BEING A LONG HOLIDAY WEEKEND WITH INCREASED 
TRAVEL...ISSUED A SPECIAL WEATHER STATEMENT TO INCREASE THE 
AWARENESS.

THE STORM EVOLVES BY SPLITTING ACROSS THE NORTHERN ROCKIES WITH JET 
SUPPORT DEEPENING THE SOUTHERN SYSTEM OVER THE GREAT BASIN. 
TEMPERATURES ALOFT ARE QUITE COLD WITH THIS SYSTEM (-15C AT 700MB 
AND -32C AT 500MB BY MONDAY MORNING). GIVEN THE STRONG NORTHWESTERLY 
COLD ADVECTION...EXPECT HIGHER SNOWRATES AND POTENTIAL IMPACT FOR 
NORTHWESTERLY FAVORED OROGRAPHICS INCLUDING INTERSTATE 15 FROM 
FILLMORE TO CEDAR CITY. WOULD LIKE TO SEE HIGHER PRECIPITABLE WATER 
VALUES AT THE LEADING EDGE OF THIS SYSTEM (CURRENTLY GFS IS CLOSE TO 
0.33" WITH NAM SHOWING VALUES UP TO 0.4") TO INCREASE CONFIDENCE 
THAT SNOWFALL WILL BE HEAVY ENOUGH ACROSS A LARGE AREA TO IMPACT 
TRAVEL.

A STRONG PACIFIC JET ARRIVES ACROSS THE PACIFIC NORTHWEST AND 
NORTHERN ROCKIES NEXT WEEK PROVIDING MOIST WARM ADVECTION ACROSS 
NORTHERN UTAH AND SOUTHWEST WYOMING.

.AVIATION...LOW CLOUDS HAVE BECOME WIDESPREAD ACROSS THE SLC 
TERMINAL AREA THIS MORNING AND ARE LIKELY TO REMAIN IN PLACE THROUGH 
ABOUT 15-16Z BEFORE DISSIPATING. AFTER 16Z A DRIER NORTHERLY FLOW 
SHOULD REMOVE ANY THREAT OF LINGERING CLOUDS. SURFACE WINDS WILL BE 
NORTHERLY THROUGH ABOUT 03Z TONIGHT THEN SHIFT TO THE SOUTHEAST.

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