Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 160953
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
253 AM MST SUN NOV 16 2014

.SYNOPSIS...HIGH PRESSURE ALOFT WILL DEVELOP OVER THE REGION
EARLY IN THE UPCOMING WEEK LEADING TO A BUILDING INVERSION.

&&

.SHORT TERM (THROUGH 12Z WEDNESDAY)...
WATER VAPOR LOOP SHOWS THE REMAINDER OF THE ARCTIC TROUGH NOW
PIVOTING SOUTHEAST TOWARD THE FOUR CORNERS. AMDAR 400-250MB WIND
OBSERVATIONS REVEAL A NORTHWESTERLY 145-165KT JET FROM WESTERN
OREGON INTO SOUTHWEST UTAH. GOES/GPS/RAP/00Z RAOB INDICATE THE
PRECIPITABLE WATER VALUE RANGES BETWEEN 0.02" NORTHEAST
MOUNTAINS...TO 0.35" SOUTHEASTERN VALLEYS.

ARCTIC AIRMASS SO DRY AND STABLE LAKE EFFECT NOT A CONCERN
DESPITE -16C AIRMASS AT 700MB EARLY THIS MORNING.

THERE IS AN ONGOING HIGH WIND EVENT ACROSS WASHINGTON COUNTY OUTSIDE
OF THE ST. GEORGE   AREA. SPECIFICALLY...THE INTERSTATE 15 CORRIDOR
FROM LEEDS TO THE IRON COUNTY BORDER...NEAR THE ST. GEORGE
AIRPORT...AND WESTERN WASHINGTON COUNTY ALONG THE BULL VALLEY AND
BEAVER DAM MOUNTAINS. THIS FAVORED SETUP ACROSS SOUTHWEST UTAH IS
DUE TO A STRONG NORTHERLY PRESSURE GRADIENT/PRESSURE RISES...AND
LOW LEVEL COLD ADVECTION.

HIGH WIND WARNING GOES THROUGH NOON. NEXT SHIFT WILL NEED TO KEEP AN
EYE ON WIND GUSTS AS SOME HIGH RESOLUTION GUIDANCE SUGGESTS ADVISORY
GUSTS MAY CONTINUE THIS AFTERNOON AND INTO THE EVENING HOURS BEFORE
THE EVENT ENDS.

WATER VAPOR SHOWS A BEAUTIFUL DRYSLOT OVERHEAD...BEHIND THE
AFOREMENTIONED TROUGH AXIS. THIS FEATURE PIVOTS SOUTHEAST ACROSS THE
REMAINDER OF THE FORECAST AREA BY 12Z OR SO. REMAINING WINTER
WEATHER HEADLINES HAVE BEEN ALLOWED TO EXPIRE.

ARCTIC AIRMASS WILL HAVE AN EFFECT ON UTAHS DIXIE...WITH A HARD
FREEZE FORECAST FOR LATE TONIGHT AND MONDAY MORNING. HAVE ISSUED A
HARD FREEZE WATCH FOR THIS AREA.

STRONG INVERSION FORECAST NEXT WEEK WITH WARMING ATOP THE CHILLY
ARCTIC AIRMASS. LOWERED FORECAST HIGHS MONDAY AND TUESDAY IN TYPICAL
INVERTED AREAS AND LOCATIONS THAT GOT SNOW OVERNIGHT. LATER SHIFTS
WILL NEED TO EVALUATE FUTURE OVERNIGHT LOWS AND FURTHER REVISIONS
LOWER TO DAYTIME HIGHS MAY BE COMING.

&&

.LONG TERM (AFTER 12Z WEDNESDAY)...
COMPLEX LONG TERM FORECAST SETTING UP...WITH SIGNIFICANT
VARIATION IN THE EVOLUTION OF THE PATTERN BETWEEN THE LONG RANGE
MODELS.

TO START...A SHORTWAVE RIDGE WILL BE CROSSING THE GREAT BASIN...WITH
WARM AIR ADVECTION ONGOING WEDNESDAY MORNING. A LOOK AT A FEW GFS
BUFR SOUNDINGS ACROSS THE VALLEYS OF NORTHERN UTAH INDICATE THE MID-
LEVEL INVERSION MAY BE OF A SUFFICIENT STRENGTH TO HINDER MIXING
ACROSS THE VALLEYS EVEN INTO WEDNESDAY AFTERNOON. CURRENT FORECAST
ALLOWS FOR SUFFICIENT AFTERNOON MIXING TO BOOST TEMPERATURES A
DEGREE OR TWO OVER TUESDAY AFTERNOON HIGHS. THIS MAY BE OVERLY
AMBITIOUS IF THE VALLEY INVERSION IS ABLE TO HOLD ON LONGER THAN
FORECAST.

BOTH THE 00Z EC AND THE 00Z GFS INDICATE A WEAKENING TROUGH WILL
APPROACH THE PACIFIC COAST WEDNESDAY AFTERNOON. THE EC WEAKENS THIS
SYSTEM QUICKER THAN THE GFS...THOUGH THE RESULTING IMPACT TO
SENSIBLE WEATHER OVER UTAH IS FAIRLY MINOR. AS THIS SYSTEM
APPROACHES THE CWA LATER WEDNESDAY INTO THURSDAY...A FEW SHOWERS ARE
POSSIBLE ACROSS MAINLY NORTHERN UTAH. LOWERED POPS DURING THIS
PERIOD A BIT BUT LEFT LOW END POPS ACROSS THE NORTHERN HALF OF UTAH.
EVEN THESE POPS MAY BE ON THE HIGH SIDE GIVEN HOW WEAK AND MOISTURE
STARVED THIS SYSTEM WILL BE AS IT CROSSES UTAH.

THINGS GET COMPLICATED PAST THURSDAY MORNING. A SERIES OF
DISTURBANCES ARE LOCATED ACROSS THE EASTERN PACIFIC...ROTATING
AROUND THE LARGE LOW NEAR THE ALEUTIAN ISLANDS. BOTH THE 00Z GFS AND
THE 00Z EC ARE HAVING DIFFICULTY NARROWING IN ON THE TIMING AND
STRENGTH OF THESE DISTURBANCES. GIVEN THIS SCENARIO THERE IS A FAIR
AMOUNT OF MODEL TO MODEL AND RUN TO RUN INCONSISTENCY WITH THE
TIMING AND STRENGTH OF THESE FEATURES AS THEY CROSS THE AREA FRIDAY
INTO EARLY NEXT WEEK.

THE BIG TAKEAWAY IS THAT BOTH MODELS FEATURE A PROGRESSIVE PATTERN
WITH PRECIPITATION POSSIBLE FROM FRIDAY THROUGH THE REMAINDER OF THE
WEEKEND. IT IS JUST DIFFICULT TO ASCERTAIN TIMING AND STRENGTH OF
ANY FEATURE. GIVEN THESE ISSUES...KEPT TEMPERATURES BELOW NORMAL AND
POPS AT OR ABOVE CLIMO.

&&

.AVIATION...NORTHWEST WINDS ARE EXPECTED TO REMAIN IN PLACE AT THE
SLC TERMINAL THROUGH THE DAY. NO SIGNIFICANT CEILINGS ARE EXPECTED.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...HIGH WIND WARNING UNTIL NOON MST TODAY FOR UTZ019.

     HARD FREEZE WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR
     UTZ019.

WY...NONE.
&&

$$

SHORT TERM...ROGOWSKI
LONG TERM/AVIATION...KRUSE

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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