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000
FXUS65 KSLC 221716
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1016 AM MST MON DEC 22 2014

.SYNOPSIS...A VERY MOIST AND STRONG NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TODAY. HIGH PRESSURE WILL BUILD
OVER THE FORECAST AREA TONIGHT THROUGH WEDNESDAY. ANOTHER STORM
SYSTEM WILL IMPACT THE AREA ON CHRISTMAS DAY.

&&

.DISCUSSION...MOIST NORTHWEST FLOW CONTINUING TO BRING COPIOUS
PRECIPITATION TO NORTHERN AND CENTRAL UTAH AS WELL AS STRONG GUSTY
WINDS TO THE HIGHER ELEVATIONS. ASSOCIATED FRONTAL BOUNDARY HAS
STALLED OVER CENTRAL UTAH BUT SHOULD PUSH SOUTHWARD THIS AFTERNOON
AS THE BACK EDGE OF THE TROUGH CONTINUES ACROSS THE FORECAST AREA.

PRECIPITATION IN ASSOCIATION WITH THE SYSTEM IS PROGGED TO
CONTINUE INTO THE AFTERNOON BEFORE TAPERING OFF EARLY THIS EVENING
AS THE SYSTEM EXITS. PRESSURE GRADIENT TIGHTENS A BIT OVER
PORTIONS OF THE AREA THIS AFTERNOON...WHICH WILL LIKELY CAUSE
WINDS TO SPIKE INTO THE ADVISORY RANGE FOR CASTLE COUNTRY AND
NORTHWEST UTAH. GOING ADVISORIES COVER THE THREAT WELL. WINDS
SHOULD START TO RELAX THIS EVENING AS THE GRADIENT WEAKENS AND
CORE OF THE STRONG JET MOVES OUT OF THE AREA.

HIGH PRESSURE IS PROGGED TO BUILD BACK INTO THE REGION TONIGHT AND
TOMORROW BEHIND THE EXITING SYSTEM...BUT WILL SHIFT EAST WEDNESDAY
AHEAD OF THE NEXT APPROACHING STORM SYSTEM. MODELS BECOMING
INCREASINGLY CONSISTENT IN MOVING THE NEXT STORM SYSTEM INTO THE
CWA EARLY CHRISTMAS DAY. WITH THE GLOBAL MODELS INDICATING A
STRONG FRONT AND AMPLE MOISTURE...SIGNIFICANT ACCUMULATIONS ARE
LOOKING MORE AND MORE LIKELY.

NO UPDATES EXPECTED TO THE FORECAST THIS MORNING.

&&

.AVIATION...SHOWERS ARE EXPECTED TO LINGER INTO THE EARLY AFTERNOON
...KEEPING CEILINGS AT THE SLC TERMINAL NEAR TO BELOW 6K AGL UNTIL
19-21Z. NORTHWEST WINDS SHOULD RAMP UP AFTER 19Z...BECOMING GUSTY
FROM 20-23Z. WINDS WILL DIMINISH AFTER THIS BUT REMAIN NORTH WELL
INTO THE LATE EVENING HOURS.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR UTZ007>010-
     517.

     WIND ADVISORY UNTIL 10 PM MST THIS EVENING FOR UTZ012.

     WIND ADVISORY UNTIL 8 PM MST THIS EVENING FOR UTZ005.

WY...NONE.
&&

$$

PUBLIC...TRAPHAGAN
AVIATION...VERZELLA

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)



000
FXUS65 KSLC 221716
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1016 AM MST MON DEC 22 2014

.SYNOPSIS...A VERY MOIST AND STRONG NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TODAY. HIGH PRESSURE WILL BUILD
OVER THE FORECAST AREA TONIGHT THROUGH WEDNESDAY. ANOTHER STORM
SYSTEM WILL IMPACT THE AREA ON CHRISTMAS DAY.

&&

.DISCUSSION...MOIST NORTHWEST FLOW CONTINUING TO BRING COPIOUS
PRECIPITATION TO NORTHERN AND CENTRAL UTAH AS WELL AS STRONG GUSTY
WINDS TO THE HIGHER ELEVATIONS. ASSOCIATED FRONTAL BOUNDARY HAS
STALLED OVER CENTRAL UTAH BUT SHOULD PUSH SOUTHWARD THIS AFTERNOON
AS THE BACK EDGE OF THE TROUGH CONTINUES ACROSS THE FORECAST AREA.

PRECIPITATION IN ASSOCIATION WITH THE SYSTEM IS PROGGED TO
CONTINUE INTO THE AFTERNOON BEFORE TAPERING OFF EARLY THIS EVENING
AS THE SYSTEM EXITS. PRESSURE GRADIENT TIGHTENS A BIT OVER
PORTIONS OF THE AREA THIS AFTERNOON...WHICH WILL LIKELY CAUSE
WINDS TO SPIKE INTO THE ADVISORY RANGE FOR CASTLE COUNTRY AND
NORTHWEST UTAH. GOING ADVISORIES COVER THE THREAT WELL. WINDS
SHOULD START TO RELAX THIS EVENING AS THE GRADIENT WEAKENS AND
CORE OF THE STRONG JET MOVES OUT OF THE AREA.

HIGH PRESSURE IS PROGGED TO BUILD BACK INTO THE REGION TONIGHT AND
TOMORROW BEHIND THE EXITING SYSTEM...BUT WILL SHIFT EAST WEDNESDAY
AHEAD OF THE NEXT APPROACHING STORM SYSTEM. MODELS BECOMING
INCREASINGLY CONSISTENT IN MOVING THE NEXT STORM SYSTEM INTO THE
CWA EARLY CHRISTMAS DAY. WITH THE GLOBAL MODELS INDICATING A
STRONG FRONT AND AMPLE MOISTURE...SIGNIFICANT ACCUMULATIONS ARE
LOOKING MORE AND MORE LIKELY.

NO UPDATES EXPECTED TO THE FORECAST THIS MORNING.

&&

.AVIATION...SHOWERS ARE EXPECTED TO LINGER INTO THE EARLY AFTERNOON
...KEEPING CEILINGS AT THE SLC TERMINAL NEAR TO BELOW 6K AGL UNTIL
19-21Z. NORTHWEST WINDS SHOULD RAMP UP AFTER 19Z...BECOMING GUSTY
FROM 20-23Z. WINDS WILL DIMINISH AFTER THIS BUT REMAIN NORTH WELL
INTO THE LATE EVENING HOURS.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR UTZ007>010-
     517.

     WIND ADVISORY UNTIL 10 PM MST THIS EVENING FOR UTZ012.

     WIND ADVISORY UNTIL 8 PM MST THIS EVENING FOR UTZ005.

WY...NONE.
&&

$$

PUBLIC...TRAPHAGAN
AVIATION...VERZELLA

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)




000
FXUS65 KSLC 221252
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
552 AM MST MON DEC 22 2014

.SYNOPSIS...A VERY MOIST AND STRONG NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TODAY. THE FLOW WILL BECOME MORE
NORTHERLY AND DRIER TONIGHT. HIGH PRESSURE WILL BUILD INTO THE
AREA TUESDAY INTO WEDNESDAY.

&&

.SHORT TERM (THRU 00Z THU)...THE STRONG MOIST NORTHWEST FLOW
PRECIPITATION AND WIND EVENT CONTINUES EARLY THIS MORNING. VALLEY
RAIN AND MTN SNOW HAS BEEN FILLING IN AGAIN LAST HOUR OR SO ACROSS
THE NRN CWA AND LIKELY EXTENDS S OUT OF RADAR RANGE INTO CENTRAL
UT.

A COLD FRONT HAS PUSHED INTO CENTRAL UT BUT HAS BECOME ILL DEFINED
AS OF EARLY THIS MORNING. EXPECT A SECONDARY SWD PUSH OF LOW
LEVEL COLD AIR THIS AFTN AND THIS SHOULD TAKE THE PRECIP PLUME SWD
WITH IT BECOMING MORE SHOWERY AND TAPERING OFF ACROSS THE NORTH.

THE CORE OF STRONG WINDS AT 600 AND 700 MB ALSO SHIFTS S LATER
TODAY AND THE STRONG RIDGETOP WINDS IN THE NRN MTNS SHOULD START
TO DROP OFF. EXISTING WINTER STORM WARNINGS WILL REMAIN UNCHANGED.

EXPECT THE SURFACE GRADIENT TO TIGHTEN UP THIS AFTN ACROSS THE CWA
BEHIND THE SECONDARY COLD PUSH AND THIS SHOULD SEND WINDS BACK
INTO THE ADVISORY RANGE ACROSS THE NW DESERTS AND ACROSS THE
DOWNSLOPE CASTLE COUNTRY AREAS OF EASTERN UT WHERE ADVISORIES
REMAIN IN EFFECT.

THE FLOW BECOMES MORE NORTHERLY TONIGHT AS THE RIDGE ALONG THE
WEST COAST AMPLIFIES AND DRIES OUT. CLEARING SKIES AND A COLDER
AIRMASS IN PLACE SHOULD SEND LOW TEMPS QUITE A BIT LOWER TUE
MORNING THAN THEY HAVE BEEN. A STRONG SURFACE HIGH BUILDING TO
OUR NORTH TUE KEEPS THE AIRMASS VERY STABLE AND DONT EXPECT MUCH
RECOVERY FROM THE COLD MORNING TEMPS IN VALLEYS PRONE TO
INVERSIONS. TEMPS WILL BE CHILLY AGAIN TUE NIGHT BUT SWLY FLOW
PICKS UP WED AHEAD OF THE NEXT PAC TROF AND SHOULD PROVIDE ENOUGH
MIXING TO SEND TEMPS BACK UP WELL ABOVE NORMAL AGAIN.

&&

.LONG TERM (AFTER 00Z THURSDAY)...VERY ACTIVE LONG TERM PORTION OF THE
FORECAST...WITH A WINTER STORM EXPECTED TO IMPACT MUCH OF UTAH FOR
CHRISTMAS DAY. A FAIRLY COLD TROUGH WILL APPROACH THE PACIFIC COAST AT
THE BEGINNING OF THE LONG TERM FORECAST PERIOD. THIS TROUGH WILL
PROGRESS EASTWARD OVERNIGHT WEDNESDAY NIGHT.

A FAIRLY STRONG COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL CROSS
WESTERN UTAH SOME TIME THURSDAY MORNING INTO EARLY THURSDAY
AFTERNOON. 700MB TEMPERATURES AHEAD OF THIS COLD FRONT NEAR 0C
ACROSS NORTHERN UTAH WILL QUICKLY FALL TO NEAR -10 TO -13C BEHIND
THE COLD FRONT. THE EXACT FRONTAL TIMING WILL REALLY IMPACT WHEN
THE RAIN/SNOW MIX WILL CHANGE TO ALL SNOW FOR THE VALLEY
LOCATIONS. MUCH OF THE MODEL GUIDANCES VARIES ON THE FRONTAL
TIMING BY ABOUT 6 HOURS OR SO...WITH SOME OF THE MODEL GUIDANCE
INDICATING A FRONTAL PASSAGE THURSDAY MORNING...WITH OTHER
GUIDANCE CLOSER TO THURSDAY AFTERNOON.

AS THE TROUGH CONTINUES EASTWARD ACROSS THE AREA THURSDAY...
PRECIPITATION WILL CONTINUE ACROSS MUCH OF THE CWA INTO THE
EVENING...BEFORE BECOMING A PREDOMINANTLY OROGRAPHICALLY DRIVEN
PRECIPITATION EVENT LATER THURSDAY NIGHT INTO EARLY FRIDAY. AT
THIS TIME...IT APPEARS THAT THE VALLEYS OF UTAH OUTSIDE OF DIXIE
WILL SEE ACCUMULATING SNOW THURSDAY AFTERNOON INTO THURSDAY NIGHT.
ONE OF THE MAIN QUESTIONS WITH THIS FORECAST IS WILL THE COLD
FRONT TIMING BE MORE LIKE THE FASTER GFS OR THE SLOWER
EC...CHANGING THE RAIN/SNOW MIX TO SNOW THURSDAY MORNING.

MODEL TO MODEL CONSISTENCY HAS BEEN LACKING WITH THIS SYSTEM OVER THE
PAST SEVERAL DAYS. HOWEVER...THE 00Z EC AND 00Z GFS HAVE BUCKED THIS
TREND. BOTH MODELS ARE ADVERTISING A STORM OF SIMILAR STRENGTH. AS
ALLUDED TO EARLIER...TIMING DIFFERENCES REMAIN...ESPECIALLY ASSOCIATED
WITH FRONTAL PASSAGE THURSDAY. LOOKING AT BOTH THE 12Z AND 00Z
CANADIAN...NAEFS AND GEFS RUNS...THE 12Z GFS WAS AN OUTLIER IN THE
ENSEMBLE GUIDANCE WITH A MAJORITY OF THE MEMBERS OF THE ENSEMBLES
SHOWING A STRONGER...DEEPER SYSTEM. THE 00Z ENSEMBLE DATA INDICATED A
BETTER OVERLAP BETWEEN THE GEFS AND THE CANADIAN ENSEMBLES...SHOWING A
FAIRLY STRONG AND COLD TROUGH. GIVEN THE INCREASING MODEL
CONSISTENCY...INCREASED POPS QUITE A BIT THURSDAY INTO FRIDAY. ALSO
INTRODUCED ACCUMULATING SNOW TO THE VALLEYS THURSDAY AFTERNOON/EVENING.

THOSE WITH PLANS TO TRAVEL THURSDAY MORNING THROUGH FRIDAY MORNING
SHOULD CONTINUE TO MONITOR FUTURE FORECASTS. ONE CONSISTENT POINT
REGARDLESS OF THE MODEL CHOSEN IS THAT IT WILL BECOME QUITE COLD BEHIND
THIS COLD FRONT AND REMAIN SO FOR MUCH OF THE REMAINDER OF THE EXTENDED
FORECAST PERIOD.

A BRIEF LULL IN THE ACTION IS EXPECTED FRIDAY AFTERNOON INTO SATURDAY
BEFORE ANOTHER TROUGH DIGS DOWN THE EAST SIDE OF THE EASTERN PACIFIC
HIGH AND MOVES INTO THE WESTERN UNITED STATES LATER SATURDAY.
SIGNIFICANT TIMING DIFFERENCES BETWEEN THE 00Z EC AND THE 00Z GFS
CONTINUE FROM EARLIER RUNS. BUMPED POPS UP ABOVE CLIMO ACROSS THE
NORTHERN HALF OF UTAH SUNDAY INTO MONDAY TO REFLECT A PERIOD OF
UNSETTLED WEATHER ACROSS THE STATE. HARD TO LATCH ON TO ANY SPECIFIC
TIMING AT THIS POINT GIVEN MODEL TO MODEL INCONSISTENCIES.

&&

.AVIATION...SHOWERS WILL CONTINUE IN THE VICINITY OF THE SLC TERMINAL
THROUGH THE MORNING AND INTO THE EARLY AFTERNOON. CEILINGS ARE EXPECTED
TO REMAIN NEAR TO BELOW 6000 FEET AGL AND WILL OCCASIONALLY DIP
INTO MVFR RANGE UNTIL 18-21Z. SOUTHERLY WINDS ARE EXPECTED TO
SHIFT BACK TO THE NORTH TO NORTHWEST BETWEEN 12-15Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR UTZ007>010-
     517.

     WIND ADVISORY UNTIL 10 PM MST THIS EVENING FOR UTZ012.

     WIND ADVISORY UNTIL 8 PM MST THIS EVENING FOR UTZ005.

WY...NONE.
&&

$$

SHORT TERM...WILENSKY
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)



000
FXUS65 KSLC 221252
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
552 AM MST MON DEC 22 2014

.SYNOPSIS...A VERY MOIST AND STRONG NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TODAY. THE FLOW WILL BECOME MORE
NORTHERLY AND DRIER TONIGHT. HIGH PRESSURE WILL BUILD INTO THE
AREA TUESDAY INTO WEDNESDAY.

&&

.SHORT TERM (THRU 00Z THU)...THE STRONG MOIST NORTHWEST FLOW
PRECIPITATION AND WIND EVENT CONTINUES EARLY THIS MORNING. VALLEY
RAIN AND MTN SNOW HAS BEEN FILLING IN AGAIN LAST HOUR OR SO ACROSS
THE NRN CWA AND LIKELY EXTENDS S OUT OF RADAR RANGE INTO CENTRAL
UT.

A COLD FRONT HAS PUSHED INTO CENTRAL UT BUT HAS BECOME ILL DEFINED
AS OF EARLY THIS MORNING. EXPECT A SECONDARY SWD PUSH OF LOW
LEVEL COLD AIR THIS AFTN AND THIS SHOULD TAKE THE PRECIP PLUME SWD
WITH IT BECOMING MORE SHOWERY AND TAPERING OFF ACROSS THE NORTH.

THE CORE OF STRONG WINDS AT 600 AND 700 MB ALSO SHIFTS S LATER
TODAY AND THE STRONG RIDGETOP WINDS IN THE NRN MTNS SHOULD START
TO DROP OFF. EXISTING WINTER STORM WARNINGS WILL REMAIN UNCHANGED.

EXPECT THE SURFACE GRADIENT TO TIGHTEN UP THIS AFTN ACROSS THE CWA
BEHIND THE SECONDARY COLD PUSH AND THIS SHOULD SEND WINDS BACK
INTO THE ADVISORY RANGE ACROSS THE NW DESERTS AND ACROSS THE
DOWNSLOPE CASTLE COUNTRY AREAS OF EASTERN UT WHERE ADVISORIES
REMAIN IN EFFECT.

THE FLOW BECOMES MORE NORTHERLY TONIGHT AS THE RIDGE ALONG THE
WEST COAST AMPLIFIES AND DRIES OUT. CLEARING SKIES AND A COLDER
AIRMASS IN PLACE SHOULD SEND LOW TEMPS QUITE A BIT LOWER TUE
MORNING THAN THEY HAVE BEEN. A STRONG SURFACE HIGH BUILDING TO
OUR NORTH TUE KEEPS THE AIRMASS VERY STABLE AND DONT EXPECT MUCH
RECOVERY FROM THE COLD MORNING TEMPS IN VALLEYS PRONE TO
INVERSIONS. TEMPS WILL BE CHILLY AGAIN TUE NIGHT BUT SWLY FLOW
PICKS UP WED AHEAD OF THE NEXT PAC TROF AND SHOULD PROVIDE ENOUGH
MIXING TO SEND TEMPS BACK UP WELL ABOVE NORMAL AGAIN.

&&

.LONG TERM (AFTER 00Z THURSDAY)...VERY ACTIVE LONG TERM PORTION OF THE
FORECAST...WITH A WINTER STORM EXPECTED TO IMPACT MUCH OF UTAH FOR
CHRISTMAS DAY. A FAIRLY COLD TROUGH WILL APPROACH THE PACIFIC COAST AT
THE BEGINNING OF THE LONG TERM FORECAST PERIOD. THIS TROUGH WILL
PROGRESS EASTWARD OVERNIGHT WEDNESDAY NIGHT.

A FAIRLY STRONG COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL CROSS
WESTERN UTAH SOME TIME THURSDAY MORNING INTO EARLY THURSDAY
AFTERNOON. 700MB TEMPERATURES AHEAD OF THIS COLD FRONT NEAR 0C
ACROSS NORTHERN UTAH WILL QUICKLY FALL TO NEAR -10 TO -13C BEHIND
THE COLD FRONT. THE EXACT FRONTAL TIMING WILL REALLY IMPACT WHEN
THE RAIN/SNOW MIX WILL CHANGE TO ALL SNOW FOR THE VALLEY
LOCATIONS. MUCH OF THE MODEL GUIDANCES VARIES ON THE FRONTAL
TIMING BY ABOUT 6 HOURS OR SO...WITH SOME OF THE MODEL GUIDANCE
INDICATING A FRONTAL PASSAGE THURSDAY MORNING...WITH OTHER
GUIDANCE CLOSER TO THURSDAY AFTERNOON.

AS THE TROUGH CONTINUES EASTWARD ACROSS THE AREA THURSDAY...
PRECIPITATION WILL CONTINUE ACROSS MUCH OF THE CWA INTO THE
EVENING...BEFORE BECOMING A PREDOMINANTLY OROGRAPHICALLY DRIVEN
PRECIPITATION EVENT LATER THURSDAY NIGHT INTO EARLY FRIDAY. AT
THIS TIME...IT APPEARS THAT THE VALLEYS OF UTAH OUTSIDE OF DIXIE
WILL SEE ACCUMULATING SNOW THURSDAY AFTERNOON INTO THURSDAY NIGHT.
ONE OF THE MAIN QUESTIONS WITH THIS FORECAST IS WILL THE COLD
FRONT TIMING BE MORE LIKE THE FASTER GFS OR THE SLOWER
EC...CHANGING THE RAIN/SNOW MIX TO SNOW THURSDAY MORNING.

MODEL TO MODEL CONSISTENCY HAS BEEN LACKING WITH THIS SYSTEM OVER THE
PAST SEVERAL DAYS. HOWEVER...THE 00Z EC AND 00Z GFS HAVE BUCKED THIS
TREND. BOTH MODELS ARE ADVERTISING A STORM OF SIMILAR STRENGTH. AS
ALLUDED TO EARLIER...TIMING DIFFERENCES REMAIN...ESPECIALLY ASSOCIATED
WITH FRONTAL PASSAGE THURSDAY. LOOKING AT BOTH THE 12Z AND 00Z
CANADIAN...NAEFS AND GEFS RUNS...THE 12Z GFS WAS AN OUTLIER IN THE
ENSEMBLE GUIDANCE WITH A MAJORITY OF THE MEMBERS OF THE ENSEMBLES
SHOWING A STRONGER...DEEPER SYSTEM. THE 00Z ENSEMBLE DATA INDICATED A
BETTER OVERLAP BETWEEN THE GEFS AND THE CANADIAN ENSEMBLES...SHOWING A
FAIRLY STRONG AND COLD TROUGH. GIVEN THE INCREASING MODEL
CONSISTENCY...INCREASED POPS QUITE A BIT THURSDAY INTO FRIDAY. ALSO
INTRODUCED ACCUMULATING SNOW TO THE VALLEYS THURSDAY AFTERNOON/EVENING.

THOSE WITH PLANS TO TRAVEL THURSDAY MORNING THROUGH FRIDAY MORNING
SHOULD CONTINUE TO MONITOR FUTURE FORECASTS. ONE CONSISTENT POINT
REGARDLESS OF THE MODEL CHOSEN IS THAT IT WILL BECOME QUITE COLD BEHIND
THIS COLD FRONT AND REMAIN SO FOR MUCH OF THE REMAINDER OF THE EXTENDED
FORECAST PERIOD.

A BRIEF LULL IN THE ACTION IS EXPECTED FRIDAY AFTERNOON INTO SATURDAY
BEFORE ANOTHER TROUGH DIGS DOWN THE EAST SIDE OF THE EASTERN PACIFIC
HIGH AND MOVES INTO THE WESTERN UNITED STATES LATER SATURDAY.
SIGNIFICANT TIMING DIFFERENCES BETWEEN THE 00Z EC AND THE 00Z GFS
CONTINUE FROM EARLIER RUNS. BUMPED POPS UP ABOVE CLIMO ACROSS THE
NORTHERN HALF OF UTAH SUNDAY INTO MONDAY TO REFLECT A PERIOD OF
UNSETTLED WEATHER ACROSS THE STATE. HARD TO LATCH ON TO ANY SPECIFIC
TIMING AT THIS POINT GIVEN MODEL TO MODEL INCONSISTENCIES.

&&

.AVIATION...SHOWERS WILL CONTINUE IN THE VICINITY OF THE SLC TERMINAL
THROUGH THE MORNING AND INTO THE EARLY AFTERNOON. CEILINGS ARE EXPECTED
TO REMAIN NEAR TO BELOW 6000 FEET AGL AND WILL OCCASIONALLY DIP
INTO MVFR RANGE UNTIL 18-21Z. SOUTHERLY WINDS ARE EXPECTED TO
SHIFT BACK TO THE NORTH TO NORTHWEST BETWEEN 12-15Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR UTZ007>010-
     517.

     WIND ADVISORY UNTIL 10 PM MST THIS EVENING FOR UTZ012.

     WIND ADVISORY UNTIL 8 PM MST THIS EVENING FOR UTZ005.

WY...NONE.
&&

$$

SHORT TERM...WILENSKY
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)



000
FXUS65 KSLC 221252
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
552 AM MST MON DEC 22 2014

.SYNOPSIS...A VERY MOIST AND STRONG NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TODAY. THE FLOW WILL BECOME MORE
NORTHERLY AND DRIER TONIGHT. HIGH PRESSURE WILL BUILD INTO THE
AREA TUESDAY INTO WEDNESDAY.

&&

.SHORT TERM (THRU 00Z THU)...THE STRONG MOIST NORTHWEST FLOW
PRECIPITATION AND WIND EVENT CONTINUES EARLY THIS MORNING. VALLEY
RAIN AND MTN SNOW HAS BEEN FILLING IN AGAIN LAST HOUR OR SO ACROSS
THE NRN CWA AND LIKELY EXTENDS S OUT OF RADAR RANGE INTO CENTRAL
UT.

A COLD FRONT HAS PUSHED INTO CENTRAL UT BUT HAS BECOME ILL DEFINED
AS OF EARLY THIS MORNING. EXPECT A SECONDARY SWD PUSH OF LOW
LEVEL COLD AIR THIS AFTN AND THIS SHOULD TAKE THE PRECIP PLUME SWD
WITH IT BECOMING MORE SHOWERY AND TAPERING OFF ACROSS THE NORTH.

THE CORE OF STRONG WINDS AT 600 AND 700 MB ALSO SHIFTS S LATER
TODAY AND THE STRONG RIDGETOP WINDS IN THE NRN MTNS SHOULD START
TO DROP OFF. EXISTING WINTER STORM WARNINGS WILL REMAIN UNCHANGED.

EXPECT THE SURFACE GRADIENT TO TIGHTEN UP THIS AFTN ACROSS THE CWA
BEHIND THE SECONDARY COLD PUSH AND THIS SHOULD SEND WINDS BACK
INTO THE ADVISORY RANGE ACROSS THE NW DESERTS AND ACROSS THE
DOWNSLOPE CASTLE COUNTRY AREAS OF EASTERN UT WHERE ADVISORIES
REMAIN IN EFFECT.

THE FLOW BECOMES MORE NORTHERLY TONIGHT AS THE RIDGE ALONG THE
WEST COAST AMPLIFIES AND DRIES OUT. CLEARING SKIES AND A COLDER
AIRMASS IN PLACE SHOULD SEND LOW TEMPS QUITE A BIT LOWER TUE
MORNING THAN THEY HAVE BEEN. A STRONG SURFACE HIGH BUILDING TO
OUR NORTH TUE KEEPS THE AIRMASS VERY STABLE AND DONT EXPECT MUCH
RECOVERY FROM THE COLD MORNING TEMPS IN VALLEYS PRONE TO
INVERSIONS. TEMPS WILL BE CHILLY AGAIN TUE NIGHT BUT SWLY FLOW
PICKS UP WED AHEAD OF THE NEXT PAC TROF AND SHOULD PROVIDE ENOUGH
MIXING TO SEND TEMPS BACK UP WELL ABOVE NORMAL AGAIN.

&&

.LONG TERM (AFTER 00Z THURSDAY)...VERY ACTIVE LONG TERM PORTION OF THE
FORECAST...WITH A WINTER STORM EXPECTED TO IMPACT MUCH OF UTAH FOR
CHRISTMAS DAY. A FAIRLY COLD TROUGH WILL APPROACH THE PACIFIC COAST AT
THE BEGINNING OF THE LONG TERM FORECAST PERIOD. THIS TROUGH WILL
PROGRESS EASTWARD OVERNIGHT WEDNESDAY NIGHT.

A FAIRLY STRONG COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL CROSS
WESTERN UTAH SOME TIME THURSDAY MORNING INTO EARLY THURSDAY
AFTERNOON. 700MB TEMPERATURES AHEAD OF THIS COLD FRONT NEAR 0C
ACROSS NORTHERN UTAH WILL QUICKLY FALL TO NEAR -10 TO -13C BEHIND
THE COLD FRONT. THE EXACT FRONTAL TIMING WILL REALLY IMPACT WHEN
THE RAIN/SNOW MIX WILL CHANGE TO ALL SNOW FOR THE VALLEY
LOCATIONS. MUCH OF THE MODEL GUIDANCES VARIES ON THE FRONTAL
TIMING BY ABOUT 6 HOURS OR SO...WITH SOME OF THE MODEL GUIDANCE
INDICATING A FRONTAL PASSAGE THURSDAY MORNING...WITH OTHER
GUIDANCE CLOSER TO THURSDAY AFTERNOON.

AS THE TROUGH CONTINUES EASTWARD ACROSS THE AREA THURSDAY...
PRECIPITATION WILL CONTINUE ACROSS MUCH OF THE CWA INTO THE
EVENING...BEFORE BECOMING A PREDOMINANTLY OROGRAPHICALLY DRIVEN
PRECIPITATION EVENT LATER THURSDAY NIGHT INTO EARLY FRIDAY. AT
THIS TIME...IT APPEARS THAT THE VALLEYS OF UTAH OUTSIDE OF DIXIE
WILL SEE ACCUMULATING SNOW THURSDAY AFTERNOON INTO THURSDAY NIGHT.
ONE OF THE MAIN QUESTIONS WITH THIS FORECAST IS WILL THE COLD
FRONT TIMING BE MORE LIKE THE FASTER GFS OR THE SLOWER
EC...CHANGING THE RAIN/SNOW MIX TO SNOW THURSDAY MORNING.

MODEL TO MODEL CONSISTENCY HAS BEEN LACKING WITH THIS SYSTEM OVER THE
PAST SEVERAL DAYS. HOWEVER...THE 00Z EC AND 00Z GFS HAVE BUCKED THIS
TREND. BOTH MODELS ARE ADVERTISING A STORM OF SIMILAR STRENGTH. AS
ALLUDED TO EARLIER...TIMING DIFFERENCES REMAIN...ESPECIALLY ASSOCIATED
WITH FRONTAL PASSAGE THURSDAY. LOOKING AT BOTH THE 12Z AND 00Z
CANADIAN...NAEFS AND GEFS RUNS...THE 12Z GFS WAS AN OUTLIER IN THE
ENSEMBLE GUIDANCE WITH A MAJORITY OF THE MEMBERS OF THE ENSEMBLES
SHOWING A STRONGER...DEEPER SYSTEM. THE 00Z ENSEMBLE DATA INDICATED A
BETTER OVERLAP BETWEEN THE GEFS AND THE CANADIAN ENSEMBLES...SHOWING A
FAIRLY STRONG AND COLD TROUGH. GIVEN THE INCREASING MODEL
CONSISTENCY...INCREASED POPS QUITE A BIT THURSDAY INTO FRIDAY. ALSO
INTRODUCED ACCUMULATING SNOW TO THE VALLEYS THURSDAY AFTERNOON/EVENING.

THOSE WITH PLANS TO TRAVEL THURSDAY MORNING THROUGH FRIDAY MORNING
SHOULD CONTINUE TO MONITOR FUTURE FORECASTS. ONE CONSISTENT POINT
REGARDLESS OF THE MODEL CHOSEN IS THAT IT WILL BECOME QUITE COLD BEHIND
THIS COLD FRONT AND REMAIN SO FOR MUCH OF THE REMAINDER OF THE EXTENDED
FORECAST PERIOD.

A BRIEF LULL IN THE ACTION IS EXPECTED FRIDAY AFTERNOON INTO SATURDAY
BEFORE ANOTHER TROUGH DIGS DOWN THE EAST SIDE OF THE EASTERN PACIFIC
HIGH AND MOVES INTO THE WESTERN UNITED STATES LATER SATURDAY.
SIGNIFICANT TIMING DIFFERENCES BETWEEN THE 00Z EC AND THE 00Z GFS
CONTINUE FROM EARLIER RUNS. BUMPED POPS UP ABOVE CLIMO ACROSS THE
NORTHERN HALF OF UTAH SUNDAY INTO MONDAY TO REFLECT A PERIOD OF
UNSETTLED WEATHER ACROSS THE STATE. HARD TO LATCH ON TO ANY SPECIFIC
TIMING AT THIS POINT GIVEN MODEL TO MODEL INCONSISTENCIES.

&&

.AVIATION...SHOWERS WILL CONTINUE IN THE VICINITY OF THE SLC TERMINAL
THROUGH THE MORNING AND INTO THE EARLY AFTERNOON. CEILINGS ARE EXPECTED
TO REMAIN NEAR TO BELOW 6000 FEET AGL AND WILL OCCASIONALLY DIP
INTO MVFR RANGE UNTIL 18-21Z. SOUTHERLY WINDS ARE EXPECTED TO
SHIFT BACK TO THE NORTH TO NORTHWEST BETWEEN 12-15Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR UTZ007>010-
     517.

     WIND ADVISORY UNTIL 10 PM MST THIS EVENING FOR UTZ012.

     WIND ADVISORY UNTIL 8 PM MST THIS EVENING FOR UTZ005.

WY...NONE.
&&

$$

SHORT TERM...WILENSKY
LONG TERM/AVIATION...KRUSE

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
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FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
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000
FXUS65 KSLC 221252
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
552 AM MST MON DEC 22 2014

.SYNOPSIS...A VERY MOIST AND STRONG NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TODAY. THE FLOW WILL BECOME MORE
NORTHERLY AND DRIER TONIGHT. HIGH PRESSURE WILL BUILD INTO THE
AREA TUESDAY INTO WEDNESDAY.

&&

.SHORT TERM (THRU 00Z THU)...THE STRONG MOIST NORTHWEST FLOW
PRECIPITATION AND WIND EVENT CONTINUES EARLY THIS MORNING. VALLEY
RAIN AND MTN SNOW HAS BEEN FILLING IN AGAIN LAST HOUR OR SO ACROSS
THE NRN CWA AND LIKELY EXTENDS S OUT OF RADAR RANGE INTO CENTRAL
UT.

A COLD FRONT HAS PUSHED INTO CENTRAL UT BUT HAS BECOME ILL DEFINED
AS OF EARLY THIS MORNING. EXPECT A SECONDARY SWD PUSH OF LOW
LEVEL COLD AIR THIS AFTN AND THIS SHOULD TAKE THE PRECIP PLUME SWD
WITH IT BECOMING MORE SHOWERY AND TAPERING OFF ACROSS THE NORTH.

THE CORE OF STRONG WINDS AT 600 AND 700 MB ALSO SHIFTS S LATER
TODAY AND THE STRONG RIDGETOP WINDS IN THE NRN MTNS SHOULD START
TO DROP OFF. EXISTING WINTER STORM WARNINGS WILL REMAIN UNCHANGED.

EXPECT THE SURFACE GRADIENT TO TIGHTEN UP THIS AFTN ACROSS THE CWA
BEHIND THE SECONDARY COLD PUSH AND THIS SHOULD SEND WINDS BACK
INTO THE ADVISORY RANGE ACROSS THE NW DESERTS AND ACROSS THE
DOWNSLOPE CASTLE COUNTRY AREAS OF EASTERN UT WHERE ADVISORIES
REMAIN IN EFFECT.

THE FLOW BECOMES MORE NORTHERLY TONIGHT AS THE RIDGE ALONG THE
WEST COAST AMPLIFIES AND DRIES OUT. CLEARING SKIES AND A COLDER
AIRMASS IN PLACE SHOULD SEND LOW TEMPS QUITE A BIT LOWER TUE
MORNING THAN THEY HAVE BEEN. A STRONG SURFACE HIGH BUILDING TO
OUR NORTH TUE KEEPS THE AIRMASS VERY STABLE AND DONT EXPECT MUCH
RECOVERY FROM THE COLD MORNING TEMPS IN VALLEYS PRONE TO
INVERSIONS. TEMPS WILL BE CHILLY AGAIN TUE NIGHT BUT SWLY FLOW
PICKS UP WED AHEAD OF THE NEXT PAC TROF AND SHOULD PROVIDE ENOUGH
MIXING TO SEND TEMPS BACK UP WELL ABOVE NORMAL AGAIN.

&&

.LONG TERM (AFTER 00Z THURSDAY)...VERY ACTIVE LONG TERM PORTION OF THE
FORECAST...WITH A WINTER STORM EXPECTED TO IMPACT MUCH OF UTAH FOR
CHRISTMAS DAY. A FAIRLY COLD TROUGH WILL APPROACH THE PACIFIC COAST AT
THE BEGINNING OF THE LONG TERM FORECAST PERIOD. THIS TROUGH WILL
PROGRESS EASTWARD OVERNIGHT WEDNESDAY NIGHT.

A FAIRLY STRONG COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL CROSS
WESTERN UTAH SOME TIME THURSDAY MORNING INTO EARLY THURSDAY
AFTERNOON. 700MB TEMPERATURES AHEAD OF THIS COLD FRONT NEAR 0C
ACROSS NORTHERN UTAH WILL QUICKLY FALL TO NEAR -10 TO -13C BEHIND
THE COLD FRONT. THE EXACT FRONTAL TIMING WILL REALLY IMPACT WHEN
THE RAIN/SNOW MIX WILL CHANGE TO ALL SNOW FOR THE VALLEY
LOCATIONS. MUCH OF THE MODEL GUIDANCES VARIES ON THE FRONTAL
TIMING BY ABOUT 6 HOURS OR SO...WITH SOME OF THE MODEL GUIDANCE
INDICATING A FRONTAL PASSAGE THURSDAY MORNING...WITH OTHER
GUIDANCE CLOSER TO THURSDAY AFTERNOON.

AS THE TROUGH CONTINUES EASTWARD ACROSS THE AREA THURSDAY...
PRECIPITATION WILL CONTINUE ACROSS MUCH OF THE CWA INTO THE
EVENING...BEFORE BECOMING A PREDOMINANTLY OROGRAPHICALLY DRIVEN
PRECIPITATION EVENT LATER THURSDAY NIGHT INTO EARLY FRIDAY. AT
THIS TIME...IT APPEARS THAT THE VALLEYS OF UTAH OUTSIDE OF DIXIE
WILL SEE ACCUMULATING SNOW THURSDAY AFTERNOON INTO THURSDAY NIGHT.
ONE OF THE MAIN QUESTIONS WITH THIS FORECAST IS WILL THE COLD
FRONT TIMING BE MORE LIKE THE FASTER GFS OR THE SLOWER
EC...CHANGING THE RAIN/SNOW MIX TO SNOW THURSDAY MORNING.

MODEL TO MODEL CONSISTENCY HAS BEEN LACKING WITH THIS SYSTEM OVER THE
PAST SEVERAL DAYS. HOWEVER...THE 00Z EC AND 00Z GFS HAVE BUCKED THIS
TREND. BOTH MODELS ARE ADVERTISING A STORM OF SIMILAR STRENGTH. AS
ALLUDED TO EARLIER...TIMING DIFFERENCES REMAIN...ESPECIALLY ASSOCIATED
WITH FRONTAL PASSAGE THURSDAY. LOOKING AT BOTH THE 12Z AND 00Z
CANADIAN...NAEFS AND GEFS RUNS...THE 12Z GFS WAS AN OUTLIER IN THE
ENSEMBLE GUIDANCE WITH A MAJORITY OF THE MEMBERS OF THE ENSEMBLES
SHOWING A STRONGER...DEEPER SYSTEM. THE 00Z ENSEMBLE DATA INDICATED A
BETTER OVERLAP BETWEEN THE GEFS AND THE CANADIAN ENSEMBLES...SHOWING A
FAIRLY STRONG AND COLD TROUGH. GIVEN THE INCREASING MODEL
CONSISTENCY...INCREASED POPS QUITE A BIT THURSDAY INTO FRIDAY. ALSO
INTRODUCED ACCUMULATING SNOW TO THE VALLEYS THURSDAY AFTERNOON/EVENING.

THOSE WITH PLANS TO TRAVEL THURSDAY MORNING THROUGH FRIDAY MORNING
SHOULD CONTINUE TO MONITOR FUTURE FORECASTS. ONE CONSISTENT POINT
REGARDLESS OF THE MODEL CHOSEN IS THAT IT WILL BECOME QUITE COLD BEHIND
THIS COLD FRONT AND REMAIN SO FOR MUCH OF THE REMAINDER OF THE EXTENDED
FORECAST PERIOD.

A BRIEF LULL IN THE ACTION IS EXPECTED FRIDAY AFTERNOON INTO SATURDAY
BEFORE ANOTHER TROUGH DIGS DOWN THE EAST SIDE OF THE EASTERN PACIFIC
HIGH AND MOVES INTO THE WESTERN UNITED STATES LATER SATURDAY.
SIGNIFICANT TIMING DIFFERENCES BETWEEN THE 00Z EC AND THE 00Z GFS
CONTINUE FROM EARLIER RUNS. BUMPED POPS UP ABOVE CLIMO ACROSS THE
NORTHERN HALF OF UTAH SUNDAY INTO MONDAY TO REFLECT A PERIOD OF
UNSETTLED WEATHER ACROSS THE STATE. HARD TO LATCH ON TO ANY SPECIFIC
TIMING AT THIS POINT GIVEN MODEL TO MODEL INCONSISTENCIES.

&&

.AVIATION...SHOWERS WILL CONTINUE IN THE VICINITY OF THE SLC TERMINAL
THROUGH THE MORNING AND INTO THE EARLY AFTERNOON. CEILINGS ARE EXPECTED
TO REMAIN NEAR TO BELOW 6000 FEET AGL AND WILL OCCASIONALLY DIP
INTO MVFR RANGE UNTIL 18-21Z. SOUTHERLY WINDS ARE EXPECTED TO
SHIFT BACK TO THE NORTH TO NORTHWEST BETWEEN 12-15Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR UTZ007>010-
     517.

     WIND ADVISORY UNTIL 10 PM MST THIS EVENING FOR UTZ012.

     WIND ADVISORY UNTIL 8 PM MST THIS EVENING FOR UTZ005.

WY...NONE.
&&

$$

SHORT TERM...WILENSKY
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...
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000
FXUS65 KSLC 220517
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1016 PM MST SUN DEC 21 2014

.SYNOPSIS...A VERY MOIST AND STRONG NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TONIGHT INTO MONDAY. A COLD
FRONT WILL MOVE SOUTH ACROSS THE AREA LATE TONIGHT AND MONDAY
BRINGING A COOLER BUT DRIER AIRMASS INTO THE REGION THROUGH
WEDNESDAY.

&&

.DISCUSSION...AN ANOMALOUSLY MOIST AIRMASS CONTINUES TO BRING
SIGNIFICANT PRECIPITATION TO THE AREA WITH THE ATMOSPHERIC RIVER
PENETRATING THE PACIFIC NORTHWEST INTO UTAH. MANY REPORTS OF STORM
TOTALS OVER TWO INCHES WATER IN THE NORTHERN MOUNTAINS SO FAR.
MOISTURE SURGE MAXING OUT THIS EVENING BUT WILL START TO GET CUT OFF
TONIGHT AS COLD FRONT CROSSING NORTHERN UTAH THIS EVENING SPREADS
DRIER AIR INTO THE AREA. FOCUS OF PRECIPITATION WILL SHIFT SOUTH TO
AROUND I-80 AND INTO THE CENTRAL UTAH MOUNTAINS WHILE PRECIPITATION
RATES START TO DECLINE CLOSER TO THE IDAHO BORDER.
HOWEVER...PRECIPITATION WILL NOT COMPLETELY END UP NORTH OWING TO
JET DYNAMICS WHICH CONTINUES THROUGH TOMORROW. IN CONJUNCTION WITH
THE COLDER AIR BEHIND THE FRONT...SNOW LEVELS WILL FALL OVERNIGHT
AND MAY REACH THE VALLEY FLOORS BY TOMORROW AFTERNOON BEFORE
PRECIPITATION TAPERS OFF. CURRENT BATCH OF WINTER STORM WARNINGS
CONTINUE.

WINDS STILL QUITE STRONG ACROSS THE HIGHER PEAKS AND WILL LIKELY NOT
SEE MUCH DECLINE THROUGH TOMORROW. ALSO STARTING TO SEE SOME
STRONGER GUSTS DOWNSLOPE ACROSS FAR NORTHWEST UTAH. AS THE GRADIENT
STRENGTHENS BEHIND THE FRONT TOMORROW...EXPECT THESE WINDS TO
INCREASE EVEN MORE. HAVE HOISTED A WIND ADVISORY AS A RESULT. ALSO
HAVE SOME CONCERN ABOUT DOWNSLOPE WINDS IN CASTLE COUNTRY WHICH
WOULD LIKELY PEAK TOMORROW AFTERNOON OR EARLY EVENING. FOR
NOW...WILL LET THE MIDNIGHT SHIFT HAVE ONE MORE LOOK AT THAT. THE
00Z MODELS DO SHOW STRONGER CROSS-BARRIER FLOW...JUST A MATTER OF
WHETHER THE AIRMASS ALLOWS THOSE STRONG WINDS TO SURFACE. WINDS
ACROSS SOUTHWEST WYOMING HAVE YET TO REACH WARNING CRITERIA.
HOWEVER...WINDS HAVE STARTED TO PICK UP AGAIN AND WITH SUCH STRONG
WINDS ALOFT WILL LET THAT WARNING CONTINUE ON.

UPDATED FORECAST FOR WIND AND ALSO MADE MINOR ADJUSTMENTS TO POP AND
SNOW LEVEL FOR A FEW ZONES.

&&

.AVIATION...SHOWERS ARE EXPECTED TO CONTINUE IN THE VICINITY OF THE
SLC TERMINAL THROUGH THE OVERNIGHT HOURS. OCCASIONAL CEILINGS NEAR
OR BELOW 6000 FEET AGL WILL REMAIN POSSIBLE THROUGH ABOUT 15-18Z.
NORTH TO NORTHWEST WINDS ARE EXPECTED TO CONTINUE AT THE TERMINAL
THROUGH THE OVERNIGHT HOURS.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.
     WIND ADVISORY UNTIL 8 PM MST MONDAY FOR UTZ005.
WY...HIGH WIND WARNING UNTIL 2 AM MST MONDAY FOR WYZ021.

&&

$$

CHENG/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)



000
FXUS65 KSLC 220517
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1016 PM MST SUN DEC 21 2014

.SYNOPSIS...A VERY MOIST AND STRONG NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TONIGHT INTO MONDAY. A COLD
FRONT WILL MOVE SOUTH ACROSS THE AREA LATE TONIGHT AND MONDAY
BRINGING A COOLER BUT DRIER AIRMASS INTO THE REGION THROUGH
WEDNESDAY.

&&

.DISCUSSION...AN ANOMALOUSLY MOIST AIRMASS CONTINUES TO BRING
SIGNIFICANT PRECIPITATION TO THE AREA WITH THE ATMOSPHERIC RIVER
PENETRATING THE PACIFIC NORTHWEST INTO UTAH. MANY REPORTS OF STORM
TOTALS OVER TWO INCHES WATER IN THE NORTHERN MOUNTAINS SO FAR.
MOISTURE SURGE MAXING OUT THIS EVENING BUT WILL START TO GET CUT OFF
TONIGHT AS COLD FRONT CROSSING NORTHERN UTAH THIS EVENING SPREADS
DRIER AIR INTO THE AREA. FOCUS OF PRECIPITATION WILL SHIFT SOUTH TO
AROUND I-80 AND INTO THE CENTRAL UTAH MOUNTAINS WHILE PRECIPITATION
RATES START TO DECLINE CLOSER TO THE IDAHO BORDER.
HOWEVER...PRECIPITATION WILL NOT COMPLETELY END UP NORTH OWING TO
JET DYNAMICS WHICH CONTINUES THROUGH TOMORROW. IN CONJUNCTION WITH
THE COLDER AIR BEHIND THE FRONT...SNOW LEVELS WILL FALL OVERNIGHT
AND MAY REACH THE VALLEY FLOORS BY TOMORROW AFTERNOON BEFORE
PRECIPITATION TAPERS OFF. CURRENT BATCH OF WINTER STORM WARNINGS
CONTINUE.

WINDS STILL QUITE STRONG ACROSS THE HIGHER PEAKS AND WILL LIKELY NOT
SEE MUCH DECLINE THROUGH TOMORROW. ALSO STARTING TO SEE SOME
STRONGER GUSTS DOWNSLOPE ACROSS FAR NORTHWEST UTAH. AS THE GRADIENT
STRENGTHENS BEHIND THE FRONT TOMORROW...EXPECT THESE WINDS TO
INCREASE EVEN MORE. HAVE HOISTED A WIND ADVISORY AS A RESULT. ALSO
HAVE SOME CONCERN ABOUT DOWNSLOPE WINDS IN CASTLE COUNTRY WHICH
WOULD LIKELY PEAK TOMORROW AFTERNOON OR EARLY EVENING. FOR
NOW...WILL LET THE MIDNIGHT SHIFT HAVE ONE MORE LOOK AT THAT. THE
00Z MODELS DO SHOW STRONGER CROSS-BARRIER FLOW...JUST A MATTER OF
WHETHER THE AIRMASS ALLOWS THOSE STRONG WINDS TO SURFACE. WINDS
ACROSS SOUTHWEST WYOMING HAVE YET TO REACH WARNING CRITERIA.
HOWEVER...WINDS HAVE STARTED TO PICK UP AGAIN AND WITH SUCH STRONG
WINDS ALOFT WILL LET THAT WARNING CONTINUE ON.

UPDATED FORECAST FOR WIND AND ALSO MADE MINOR ADJUSTMENTS TO POP AND
SNOW LEVEL FOR A FEW ZONES.

&&

.AVIATION...SHOWERS ARE EXPECTED TO CONTINUE IN THE VICINITY OF THE
SLC TERMINAL THROUGH THE OVERNIGHT HOURS. OCCASIONAL CEILINGS NEAR
OR BELOW 6000 FEET AGL WILL REMAIN POSSIBLE THROUGH ABOUT 15-18Z.
NORTH TO NORTHWEST WINDS ARE EXPECTED TO CONTINUE AT THE TERMINAL
THROUGH THE OVERNIGHT HOURS.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.
     WIND ADVISORY UNTIL 8 PM MST MONDAY FOR UTZ005.
WY...HIGH WIND WARNING UNTIL 2 AM MST MONDAY FOR WYZ021.

&&

$$

CHENG/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)



000
FXUS65 KSLC 220517
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1016 PM MST SUN DEC 21 2014

.SYNOPSIS...A VERY MOIST AND STRONG NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TONIGHT INTO MONDAY. A COLD
FRONT WILL MOVE SOUTH ACROSS THE AREA LATE TONIGHT AND MONDAY
BRINGING A COOLER BUT DRIER AIRMASS INTO THE REGION THROUGH
WEDNESDAY.

&&

.DISCUSSION...AN ANOMALOUSLY MOIST AIRMASS CONTINUES TO BRING
SIGNIFICANT PRECIPITATION TO THE AREA WITH THE ATMOSPHERIC RIVER
PENETRATING THE PACIFIC NORTHWEST INTO UTAH. MANY REPORTS OF STORM
TOTALS OVER TWO INCHES WATER IN THE NORTHERN MOUNTAINS SO FAR.
MOISTURE SURGE MAXING OUT THIS EVENING BUT WILL START TO GET CUT OFF
TONIGHT AS COLD FRONT CROSSING NORTHERN UTAH THIS EVENING SPREADS
DRIER AIR INTO THE AREA. FOCUS OF PRECIPITATION WILL SHIFT SOUTH TO
AROUND I-80 AND INTO THE CENTRAL UTAH MOUNTAINS WHILE PRECIPITATION
RATES START TO DECLINE CLOSER TO THE IDAHO BORDER.
HOWEVER...PRECIPITATION WILL NOT COMPLETELY END UP NORTH OWING TO
JET DYNAMICS WHICH CONTINUES THROUGH TOMORROW. IN CONJUNCTION WITH
THE COLDER AIR BEHIND THE FRONT...SNOW LEVELS WILL FALL OVERNIGHT
AND MAY REACH THE VALLEY FLOORS BY TOMORROW AFTERNOON BEFORE
PRECIPITATION TAPERS OFF. CURRENT BATCH OF WINTER STORM WARNINGS
CONTINUE.

WINDS STILL QUITE STRONG ACROSS THE HIGHER PEAKS AND WILL LIKELY NOT
SEE MUCH DECLINE THROUGH TOMORROW. ALSO STARTING TO SEE SOME
STRONGER GUSTS DOWNSLOPE ACROSS FAR NORTHWEST UTAH. AS THE GRADIENT
STRENGTHENS BEHIND THE FRONT TOMORROW...EXPECT THESE WINDS TO
INCREASE EVEN MORE. HAVE HOISTED A WIND ADVISORY AS A RESULT. ALSO
HAVE SOME CONCERN ABOUT DOWNSLOPE WINDS IN CASTLE COUNTRY WHICH
WOULD LIKELY PEAK TOMORROW AFTERNOON OR EARLY EVENING. FOR
NOW...WILL LET THE MIDNIGHT SHIFT HAVE ONE MORE LOOK AT THAT. THE
00Z MODELS DO SHOW STRONGER CROSS-BARRIER FLOW...JUST A MATTER OF
WHETHER THE AIRMASS ALLOWS THOSE STRONG WINDS TO SURFACE. WINDS
ACROSS SOUTHWEST WYOMING HAVE YET TO REACH WARNING CRITERIA.
HOWEVER...WINDS HAVE STARTED TO PICK UP AGAIN AND WITH SUCH STRONG
WINDS ALOFT WILL LET THAT WARNING CONTINUE ON.

UPDATED FORECAST FOR WIND AND ALSO MADE MINOR ADJUSTMENTS TO POP AND
SNOW LEVEL FOR A FEW ZONES.

&&

.AVIATION...SHOWERS ARE EXPECTED TO CONTINUE IN THE VICINITY OF THE
SLC TERMINAL THROUGH THE OVERNIGHT HOURS. OCCASIONAL CEILINGS NEAR
OR BELOW 6000 FEET AGL WILL REMAIN POSSIBLE THROUGH ABOUT 15-18Z.
NORTH TO NORTHWEST WINDS ARE EXPECTED TO CONTINUE AT THE TERMINAL
THROUGH THE OVERNIGHT HOURS.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.
     WIND ADVISORY UNTIL 8 PM MST MONDAY FOR UTZ005.
WY...HIGH WIND WARNING UNTIL 2 AM MST MONDAY FOR WYZ021.

&&

$$

CHENG/KRUSE

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

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VISIT...
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000
FXUS65 KSLC 220517
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1016 PM MST SUN DEC 21 2014

.SYNOPSIS...A VERY MOIST AND STRONG NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TONIGHT INTO MONDAY. A COLD
FRONT WILL MOVE SOUTH ACROSS THE AREA LATE TONIGHT AND MONDAY
BRINGING A COOLER BUT DRIER AIRMASS INTO THE REGION THROUGH
WEDNESDAY.

&&

.DISCUSSION...AN ANOMALOUSLY MOIST AIRMASS CONTINUES TO BRING
SIGNIFICANT PRECIPITATION TO THE AREA WITH THE ATMOSPHERIC RIVER
PENETRATING THE PACIFIC NORTHWEST INTO UTAH. MANY REPORTS OF STORM
TOTALS OVER TWO INCHES WATER IN THE NORTHERN MOUNTAINS SO FAR.
MOISTURE SURGE MAXING OUT THIS EVENING BUT WILL START TO GET CUT OFF
TONIGHT AS COLD FRONT CROSSING NORTHERN UTAH THIS EVENING SPREADS
DRIER AIR INTO THE AREA. FOCUS OF PRECIPITATION WILL SHIFT SOUTH TO
AROUND I-80 AND INTO THE CENTRAL UTAH MOUNTAINS WHILE PRECIPITATION
RATES START TO DECLINE CLOSER TO THE IDAHO BORDER.
HOWEVER...PRECIPITATION WILL NOT COMPLETELY END UP NORTH OWING TO
JET DYNAMICS WHICH CONTINUES THROUGH TOMORROW. IN CONJUNCTION WITH
THE COLDER AIR BEHIND THE FRONT...SNOW LEVELS WILL FALL OVERNIGHT
AND MAY REACH THE VALLEY FLOORS BY TOMORROW AFTERNOON BEFORE
PRECIPITATION TAPERS OFF. CURRENT BATCH OF WINTER STORM WARNINGS
CONTINUE.

WINDS STILL QUITE STRONG ACROSS THE HIGHER PEAKS AND WILL LIKELY NOT
SEE MUCH DECLINE THROUGH TOMORROW. ALSO STARTING TO SEE SOME
STRONGER GUSTS DOWNSLOPE ACROSS FAR NORTHWEST UTAH. AS THE GRADIENT
STRENGTHENS BEHIND THE FRONT TOMORROW...EXPECT THESE WINDS TO
INCREASE EVEN MORE. HAVE HOISTED A WIND ADVISORY AS A RESULT. ALSO
HAVE SOME CONCERN ABOUT DOWNSLOPE WINDS IN CASTLE COUNTRY WHICH
WOULD LIKELY PEAK TOMORROW AFTERNOON OR EARLY EVENING. FOR
NOW...WILL LET THE MIDNIGHT SHIFT HAVE ONE MORE LOOK AT THAT. THE
00Z MODELS DO SHOW STRONGER CROSS-BARRIER FLOW...JUST A MATTER OF
WHETHER THE AIRMASS ALLOWS THOSE STRONG WINDS TO SURFACE. WINDS
ACROSS SOUTHWEST WYOMING HAVE YET TO REACH WARNING CRITERIA.
HOWEVER...WINDS HAVE STARTED TO PICK UP AGAIN AND WITH SUCH STRONG
WINDS ALOFT WILL LET THAT WARNING CONTINUE ON.

UPDATED FORECAST FOR WIND AND ALSO MADE MINOR ADJUSTMENTS TO POP AND
SNOW LEVEL FOR A FEW ZONES.

&&

.AVIATION...SHOWERS ARE EXPECTED TO CONTINUE IN THE VICINITY OF THE
SLC TERMINAL THROUGH THE OVERNIGHT HOURS. OCCASIONAL CEILINGS NEAR
OR BELOW 6000 FEET AGL WILL REMAIN POSSIBLE THROUGH ABOUT 15-18Z.
NORTH TO NORTHWEST WINDS ARE EXPECTED TO CONTINUE AT THE TERMINAL
THROUGH THE OVERNIGHT HOURS.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.
     WIND ADVISORY UNTIL 8 PM MST MONDAY FOR UTZ005.
WY...HIGH WIND WARNING UNTIL 2 AM MST MONDAY FOR WYZ021.

&&

$$

CHENG/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...
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000
FXUS65 KSLC 212326
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
426 PM MST SUN DEC 21 2014

.SYNOPSIS...A VERY MOIST AND STRONG NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TONIGHT INTO MONDAY. A COLD
FRONT WILL MOVE SOUTH ACROSS THE AREA LATE TONIGHT AND MONDAY
BRINGING A COOLER BUT DRIER AIRMASS INTO THE REGION THROUGH
WEDNESDAY.

&&

.SHORT TERM (UNTIL 00Z THURSDAY)...A BROAD RIDGE AXIS REMAINS
SITUATED OFF OF THE WEST COAST KEEPING UTAH AND SOUTHWEST WYOMING
BENEATH A REGION OF STRONG NORTHWEST FLOW. THIS NORTHWEST FLOW IS
ASSOCIATED WITH AN INLAND PENETRATING ATMOSPHERIC RIVER WHICH IS
BRINGING AN ANOMALOUSLY MOIST AIRMASS OVER UTAH. THE PRECIPITABLE
WATER VALUE OF .58" ON THIS MORNING/S KSLC SOUNDING WAS TWO
STANDARD DEVIATIONS ABOVE NORMAL. FOR THIS TIME OF YEAR...THE
FORECAST 700 HPA WINDS FOR THIS EVENING OVER NRN UTAH ARE 3 TO 4
STANDARD DEVIATIONS ABOVE NORMAL WITH A RETURN INTERVAL OF
OCCURRENCE OF ABOUT ONCE EVERY TEN YEARS. SO...CERTAINLY A
SIGNIFICANT EVENT UNDERWAY. THIS STRONG MOIST NORTHWEST FLOW IS
ASSOCIATED WITH SIGNIFICANT ISENTROPIC UPGLIDE AND SPEED
CONVERGENCE ACROSS NRN UTAH WHICH HAS LED TO WIDESPREAD
PRECIPITATION LAST NIGHT THROUGH TODAY. ANTICIPATE THIS WILL
CONTINUE THROUGH TONIGHT BEFORE PRECIP BEGINS TO DECREASE ON
MONDAY. SOME VERY SIGNIFICANT SNOW WATER EQUIVALENT TOTALS...IN
EXCESS 2.5"...ARE COMING IN THIS AFTERNOON AND BELIEVE THAT SOME
LOCATIONS WILL RECEIVE AN ADDITIONAL 1" OF SWE TONIGHT.

SNOW LEVELS THIS AFTERNOON HAVE RISEN TO AT LEAST 7500 FEET AND
THEY WILL REMAIN HIGH THROUGH THE EVENING. HOWEVER...A SHORTWAVE
DROPPING INTO THE BACKSIDE OF A TROUGH IN THE NORTHERN PLAINS WILL
NUDGE A BACKDOOR COLD FRONT INTO NRN UT AND SW WY LATER TONIGHT.
AS THE THE COLD AIR ASSOCIATED WITH THIS WAVE MOVES INTO UTAH
SNOW LEVELS WILL DROP AND ANTICIPATE THAT WE WILL AT LEAST SEE
SOME SLUSHY ROADS IN THE WASATCH MOUNTAIN VALLEYS AND OVER PARLEYS
SUMMIT FOR THE MONDAY MORNING COMMUTE. AS THE FRONT MOVES THROUGH
NRN UT THE FLOW WILL SWITCH TO THE NORTH AND BEGIN USHERING DRIER
AIR INTO THE REGION. ANTICIPATE THAT THE WASATCH MOUNTAINS WILL
CONTINUE TO RECEIVE SNOW THROUGH MONDAY MORNING BEFORE
DIMINISHING. WHILE THE PRECIP DECREASES ACROSS NRN UT BY MIDDAY
ON MONDAY...THE REMNANTS OF THE MOISTURE PLUME WILL SHIFT SOUTH
CONTINUING PRECIP IN CENTRAL THROUGH THE DAY. THE WINTER STORM
WARNINGS CURRENTLY IN PLACE FOR THE NORTHERN AND CENTRAL MOUNTAINS
WILL CONTINUE THROUGH 600 PM MONDAY EVENING.


IN ADDITION TO THE HEAVY PRECIPITATION...THERE IS A SIGNIFICANT
WIND EVENT UNDERWAY. EXPOSED RIDGETOPS HAVE EXPERIENCED
INCREASINGLY STRONG GUSTS THROUGH THE AFTERNOON WITH A COUPLE OF
SITES GUSTING OVER 90 MPH. THE STRONG WINDS WILL CONTINUE TONIGHT
WITH THE POTENTIAL FOR 100 MPH GUSTS IN THE MOST FAVORED
LOCATIONS ABOVE 11000 FEET. WINDS WILL REMAIN STRONG ALONG
RIDGETOPS IN NORTHERN UTAH ON MONDAY ALTHOUGH THEY WILL BACK DOWN
A FAIR AMOUNT FROM THIS AFTERNOON`S VALUES. STRONG WINDS WILL ALSO
CONTINUE ACROSS SOUTHWEST WYOMING THIS EVENING BEFORE DIMINISHING
OVERNIGHT. THERE WILL ALSO BE THE POTENTIAL FOR A BIT OF A
DOWNSLOPE WIND EVENT IN UTAH/S CASTLE COUNTRY MONDAY AFTERNOON AND
EVENING AS STRONG NORTHWEST FLOW CONTINUES AND AN INVERSION
DEVELOPS ABOVE CREST LEVEL. THE WINDOW FOR SUCH AN EVENT IS FAIRLY
SHORT AS THE FLOW ALOFT BECOMES NORTHERLY LATER MONDAY NIGHT.

MONDAY NIGHT DRIER OVERSPREADS THE REGION AS THE UPPER LEVEL
RIDGE CURRENTLY OFF OF THE WEST COAST SHARPENS AND MOVES OVER THE
WESTERN U.S THE RIDGE THEN SHIFTS EAST ACROSS THE GREAT BASIN
RESULTING IN A PERIOD OF DRY WEATHER OVER THE EASTERN GREAT BASIN
FOR TUESDAY AND WEDNESDAY AHEAD ANOTHER STORM SYSTEM.

.LONG TERM (AFTER 00Z THURSDAY)...GLOBAL MODELS CONTINUE TO INDICATE
A STORM SYSTEM IMPACTING FOR FORECAST AREA WEDNESDAY NIGHT THROUGH
CHRISTMAS BUT CONTINUE TO HAVE A HARD TIME WITH THE DETAILS. THE
STORM IS MUCH MORE OF A DIRECT HIT IN THE LATEST ECMWF
SOLUTION...WITH A QUICK MOVING COLD FRONT AND A DECENT AMOUNT OF
MOISTURE. 700 MB TEMPS AS LOW AS -14C WOULD QUICKLY BRING SNOW
LEVELS DOWN TO VALLEY FLOORS. TRACK OF THE SYSTEM WOULD CONFINE
PRECIP TO PRIMARILY NORTHERN AND CENTRAL UTAH. LATEST GFS BRINGS A
SIMILAR AMOUNT OF COLD AIR WITH THE FRONT...BUT KEEPS THE MAIN
SYSTEM NORTH OF THE AREA...RESULTING IN A MOISTURE STARVED FRONT FOR
NORTHERN UTAH. THINK AT THIS TIME IT LOOKS LIKE AT LEAST THE
MOUNTAINS OF NORTHERN UTAH WILL SEE SOMETHING ON CHRISTMAS DAY...BUT
LACK OF RUN-TO-RUN CONSISTENCY MEANS LOWER THAN USUAL CONFIDENCE ON
ANYTHING ELSE RELATING TO THE SYSTEM. GOING POP GRIDS SEEMED TO
COVER THE POTENTIAL SCENARIOS WELL SO MADE FEW CHANGES.

EC/GFS SHOW A SECOND TRAILING WAVE BEHIND THE MAIN SYSTEM FOR
THURSDAY NIGHT/FRIDAY BUT AGAIN...THIS IS MUCH STRONGER IN THE ECMWF
SOLUTION. THIS DOES KEEP AT LEAST A SMALL THREAT OF NORTHERN
MOUNTAIN PRECIP THROUGH FRIDAY EVENING BEFORE HIGH PRESSURE MOVES
BACK IN. GFS MOVES ANOTHER PACIFIC NORTHWEST TROUGH INTO THE
FORECAST AREA ON SUNDAY. HOWEVER...IN THE ECMWF THIS SYSTEM HOLDS
OFF UNTIL MONDAY/TUESDAY. RAISED POPS A BIT AROUND DAY 7 TO ACCOUNT
FOR THIS POTENTIAL INSTABILITY.


&&

.AVIATION...VFR CONDITIONS ARE EXPECTED THROUGH THE EARLY EVENING
WITH CIGS TENDING TO STAY AT OR BELOW 6000 FT AGL WITH RAIN SHOWERS
IN THE VICINITY OF THE TERMINAL. THERE IS A 30 PERCENT CHANCE OF A
BRIEF PERIOD OF MVFR CONDITIONS IF HEAVIER SHOWERS DEVELOP. THE BEST
CHANCE FOR THIS TO OCCUR IS BEFORE 03Z. SOUTHEAST WINDS ARE EXPECTED
TO SHIFT TO THE NORTHWEST BETWEEN 00Z AND 02Z WITH THE PASSAGE OF A
COLD FRONT. THERE IS A 30 PERCENT CHANCE THAT THE FRONT WILL MOVE
THROUGH LATER THAN EXPECTED.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.

WY...HIGH WIND WARNING UNTIL 2 AM MST MONDAY FOR WYZ021.

&&

$$

SHORT TERM...GRAHAM
LONG TERM...TRAPHAGAN
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)




000
FXUS65 KSLC 212326
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
426 PM MST SUN DEC 21 2014

.SYNOPSIS...A VERY MOIST AND STRONG NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TONIGHT INTO MONDAY. A COLD
FRONT WILL MOVE SOUTH ACROSS THE AREA LATE TONIGHT AND MONDAY
BRINGING A COOLER BUT DRIER AIRMASS INTO THE REGION THROUGH
WEDNESDAY.

&&

.SHORT TERM (UNTIL 00Z THURSDAY)...A BROAD RIDGE AXIS REMAINS
SITUATED OFF OF THE WEST COAST KEEPING UTAH AND SOUTHWEST WYOMING
BENEATH A REGION OF STRONG NORTHWEST FLOW. THIS NORTHWEST FLOW IS
ASSOCIATED WITH AN INLAND PENETRATING ATMOSPHERIC RIVER WHICH IS
BRINGING AN ANOMALOUSLY MOIST AIRMASS OVER UTAH. THE PRECIPITABLE
WATER VALUE OF .58" ON THIS MORNING/S KSLC SOUNDING WAS TWO
STANDARD DEVIATIONS ABOVE NORMAL. FOR THIS TIME OF YEAR...THE
FORECAST 700 HPA WINDS FOR THIS EVENING OVER NRN UTAH ARE 3 TO 4
STANDARD DEVIATIONS ABOVE NORMAL WITH A RETURN INTERVAL OF
OCCURRENCE OF ABOUT ONCE EVERY TEN YEARS. SO...CERTAINLY A
SIGNIFICANT EVENT UNDERWAY. THIS STRONG MOIST NORTHWEST FLOW IS
ASSOCIATED WITH SIGNIFICANT ISENTROPIC UPGLIDE AND SPEED
CONVERGENCE ACROSS NRN UTAH WHICH HAS LED TO WIDESPREAD
PRECIPITATION LAST NIGHT THROUGH TODAY. ANTICIPATE THIS WILL
CONTINUE THROUGH TONIGHT BEFORE PRECIP BEGINS TO DECREASE ON
MONDAY. SOME VERY SIGNIFICANT SNOW WATER EQUIVALENT TOTALS...IN
EXCESS 2.5"...ARE COMING IN THIS AFTERNOON AND BELIEVE THAT SOME
LOCATIONS WILL RECEIVE AN ADDITIONAL 1" OF SWE TONIGHT.

SNOW LEVELS THIS AFTERNOON HAVE RISEN TO AT LEAST 7500 FEET AND
THEY WILL REMAIN HIGH THROUGH THE EVENING. HOWEVER...A SHORTWAVE
DROPPING INTO THE BACKSIDE OF A TROUGH IN THE NORTHERN PLAINS WILL
NUDGE A BACKDOOR COLD FRONT INTO NRN UT AND SW WY LATER TONIGHT.
AS THE THE COLD AIR ASSOCIATED WITH THIS WAVE MOVES INTO UTAH
SNOW LEVELS WILL DROP AND ANTICIPATE THAT WE WILL AT LEAST SEE
SOME SLUSHY ROADS IN THE WASATCH MOUNTAIN VALLEYS AND OVER PARLEYS
SUMMIT FOR THE MONDAY MORNING COMMUTE. AS THE FRONT MOVES THROUGH
NRN UT THE FLOW WILL SWITCH TO THE NORTH AND BEGIN USHERING DRIER
AIR INTO THE REGION. ANTICIPATE THAT THE WASATCH MOUNTAINS WILL
CONTINUE TO RECEIVE SNOW THROUGH MONDAY MORNING BEFORE
DIMINISHING. WHILE THE PRECIP DECREASES ACROSS NRN UT BY MIDDAY
ON MONDAY...THE REMNANTS OF THE MOISTURE PLUME WILL SHIFT SOUTH
CONTINUING PRECIP IN CENTRAL THROUGH THE DAY. THE WINTER STORM
WARNINGS CURRENTLY IN PLACE FOR THE NORTHERN AND CENTRAL MOUNTAINS
WILL CONTINUE THROUGH 600 PM MONDAY EVENING.


IN ADDITION TO THE HEAVY PRECIPITATION...THERE IS A SIGNIFICANT
WIND EVENT UNDERWAY. EXPOSED RIDGETOPS HAVE EXPERIENCED
INCREASINGLY STRONG GUSTS THROUGH THE AFTERNOON WITH A COUPLE OF
SITES GUSTING OVER 90 MPH. THE STRONG WINDS WILL CONTINUE TONIGHT
WITH THE POTENTIAL FOR 100 MPH GUSTS IN THE MOST FAVORED
LOCATIONS ABOVE 11000 FEET. WINDS WILL REMAIN STRONG ALONG
RIDGETOPS IN NORTHERN UTAH ON MONDAY ALTHOUGH THEY WILL BACK DOWN
A FAIR AMOUNT FROM THIS AFTERNOON`S VALUES. STRONG WINDS WILL ALSO
CONTINUE ACROSS SOUTHWEST WYOMING THIS EVENING BEFORE DIMINISHING
OVERNIGHT. THERE WILL ALSO BE THE POTENTIAL FOR A BIT OF A
DOWNSLOPE WIND EVENT IN UTAH/S CASTLE COUNTRY MONDAY AFTERNOON AND
EVENING AS STRONG NORTHWEST FLOW CONTINUES AND AN INVERSION
DEVELOPS ABOVE CREST LEVEL. THE WINDOW FOR SUCH AN EVENT IS FAIRLY
SHORT AS THE FLOW ALOFT BECOMES NORTHERLY LATER MONDAY NIGHT.

MONDAY NIGHT DRIER OVERSPREADS THE REGION AS THE UPPER LEVEL
RIDGE CURRENTLY OFF OF THE WEST COAST SHARPENS AND MOVES OVER THE
WESTERN U.S THE RIDGE THEN SHIFTS EAST ACROSS THE GREAT BASIN
RESULTING IN A PERIOD OF DRY WEATHER OVER THE EASTERN GREAT BASIN
FOR TUESDAY AND WEDNESDAY AHEAD ANOTHER STORM SYSTEM.

.LONG TERM (AFTER 00Z THURSDAY)...GLOBAL MODELS CONTINUE TO INDICATE
A STORM SYSTEM IMPACTING FOR FORECAST AREA WEDNESDAY NIGHT THROUGH
CHRISTMAS BUT CONTINUE TO HAVE A HARD TIME WITH THE DETAILS. THE
STORM IS MUCH MORE OF A DIRECT HIT IN THE LATEST ECMWF
SOLUTION...WITH A QUICK MOVING COLD FRONT AND A DECENT AMOUNT OF
MOISTURE. 700 MB TEMPS AS LOW AS -14C WOULD QUICKLY BRING SNOW
LEVELS DOWN TO VALLEY FLOORS. TRACK OF THE SYSTEM WOULD CONFINE
PRECIP TO PRIMARILY NORTHERN AND CENTRAL UTAH. LATEST GFS BRINGS A
SIMILAR AMOUNT OF COLD AIR WITH THE FRONT...BUT KEEPS THE MAIN
SYSTEM NORTH OF THE AREA...RESULTING IN A MOISTURE STARVED FRONT FOR
NORTHERN UTAH. THINK AT THIS TIME IT LOOKS LIKE AT LEAST THE
MOUNTAINS OF NORTHERN UTAH WILL SEE SOMETHING ON CHRISTMAS DAY...BUT
LACK OF RUN-TO-RUN CONSISTENCY MEANS LOWER THAN USUAL CONFIDENCE ON
ANYTHING ELSE RELATING TO THE SYSTEM. GOING POP GRIDS SEEMED TO
COVER THE POTENTIAL SCENARIOS WELL SO MADE FEW CHANGES.

EC/GFS SHOW A SECOND TRAILING WAVE BEHIND THE MAIN SYSTEM FOR
THURSDAY NIGHT/FRIDAY BUT AGAIN...THIS IS MUCH STRONGER IN THE ECMWF
SOLUTION. THIS DOES KEEP AT LEAST A SMALL THREAT OF NORTHERN
MOUNTAIN PRECIP THROUGH FRIDAY EVENING BEFORE HIGH PRESSURE MOVES
BACK IN. GFS MOVES ANOTHER PACIFIC NORTHWEST TROUGH INTO THE
FORECAST AREA ON SUNDAY. HOWEVER...IN THE ECMWF THIS SYSTEM HOLDS
OFF UNTIL MONDAY/TUESDAY. RAISED POPS A BIT AROUND DAY 7 TO ACCOUNT
FOR THIS POTENTIAL INSTABILITY.


&&

.AVIATION...VFR CONDITIONS ARE EXPECTED THROUGH THE EARLY EVENING
WITH CIGS TENDING TO STAY AT OR BELOW 6000 FT AGL WITH RAIN SHOWERS
IN THE VICINITY OF THE TERMINAL. THERE IS A 30 PERCENT CHANCE OF A
BRIEF PERIOD OF MVFR CONDITIONS IF HEAVIER SHOWERS DEVELOP. THE BEST
CHANCE FOR THIS TO OCCUR IS BEFORE 03Z. SOUTHEAST WINDS ARE EXPECTED
TO SHIFT TO THE NORTHWEST BETWEEN 00Z AND 02Z WITH THE PASSAGE OF A
COLD FRONT. THERE IS A 30 PERCENT CHANCE THAT THE FRONT WILL MOVE
THROUGH LATER THAN EXPECTED.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.

WY...HIGH WIND WARNING UNTIL 2 AM MST MONDAY FOR WYZ021.

&&

$$

SHORT TERM...GRAHAM
LONG TERM...TRAPHAGAN
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)



000
FXUS65 KSLC 211826
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1126 AM MST SUN DEC 21 2014

.SYNOPSIS...A VERY MILD AND MOIST NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TODAY INTO TONIGHT. A COLD FRONT
WILL MOVE SOUTH ACROSS THE AREA LATE TONIGHT AND MONDAY BRINGING
A COOLER BUT DRIER AIRMASS INTO THE REGION THROUGH WEDNESDAY.

&&

.DISCUSSION...BROAD RIDGE AXIS SITUATED OFF OF THE WEST COAST
PLACING UTAH UNDER STRONG NORTHWEST FLOW. OVER THE TOP OF THE
RIDGE A SIGNIFICANT INLAND PENETRATING ATMOSPHERIC RIVER IS
BRINGING A SUBSTANTIAL AMOUNT OF MOISTURE INTO NORTHERN UTAH AND
SOUTHWEST WYOMING TODAY. THE 1200 UTC KSLC SOUNDING HAD .58"
PRECIPITABLE WATER...WHICH IS 2 STANDARD DEVIATIONS ABOVE NORMAL
FOR THIS TIME OF YEAR. IN ADDITION TO THE SUBSTANTIAL MOISTURE
PLUME...NORTHWEST FLOW ALOFT IS VERY STRONG WITH 80-90 KNOTS OF
FLOW EXPECTED AT 500 HPA OVER NORTHERN UTAH AND SOUTHWEST WYOMING
THIS AFTERNOON. THE COMBINATION OF ANOMALOUSLY DEEP MOISTURE AND
STRONG FLOW POINTS TO AN UNUSUAL EVENT UNDERWAY WITH FORECAST
INTEGRATED WATER VAPOR TRANSPORT VALUES HAVING RETURN INTERVALS OF
ONCE EVERY 20+ YEARS. THE STRONG AND VERY MOIST FLOW IS OCCURRING
IN A MODEST WARM ADVECTION ENVIRONMENT WHICH YIELDS SIGNIFICANT
ISENTROPIC UPGLIDE THROUGH THE EVENING HOURS. WITH THIS IN MIND
EXPECT WIDESPREAD PRECIPITATION TO CONTINUE ACROSS NRN UT AND SW
WY THROUGH THIS EVENING WITH AN INCREASE IN INTENSITY FOR MOST
AREAS.

ALSO...WITH VERY STRONG WIND ALOFT ANTICIPATE THAT HIGH
WINDS..WITH GUSTS TO 60 MPH...WILL DEVELOP ACROSS SW WY TODAY.
ACROSS NRN UT RIDGETOP WINDS MAY BE QUITE SIGNIFICANT WITH THE
HIGHEST EXPOSED PEAKS IN THE WASATCH POTENTIALLY RECEIVING 90+ MPH
WIND GUSTS THIS AFTERNOON AND EVENING. ONGOING WINTER STORM
WARNINGS FOR UTAH/S NORTHERN AND CENTRAL MOUNTAINS LOOK TO BE IN
GOOD SHAPE AS DOES THE HIGH WIND WARNING FOR SOUTHWEST WY. BELIEVE
THAT MOST SIGNIFICANT SNOW AMOUNTS WILL BE IN THE WASATCH RANGE
NORTH OF I-80 WHERE STORM TOTALS OF 24+ INCHES OF SNOW ARE
POSSIBLE...IN THE MOST FAVORED AREAS...BY THE TIME THE STORM WINDS
DOWN ON MONDAY. FURTHER SOUTH...THE 10-20" RANGE STILL LOOKS GOOD
FOR THE WASATCH MOUNTAINS SOUTH OF I-80...ALTHOUGH LOCALLY HIGHER
AMOUNTS WILL BE POSSIBLE ABOVE 8500 FEET.

SNOW LEVELS HAVE BEEN A BIT STUBBORN AND HAVE BEEN SLOW TO RISE
THIS MORNING. HOWEVER...STILL ANTICIPATE THAT THEY WILL RISE THIS
AFTERNOON. HAVE TRENDED THE SNOW LEVELS DOWN A BIT AND NOW
ANTICIPATE THAT THE SNOW LEVEL WILL RISE TO 7000-7500 AGL THIS
AFTERNOON/EVENING.

A SHORTWAVE DROPPING INTO THE BACKSIDE OF A TROUGH IN THE NORTHERN
PLAINS WILL NUDGE A BACKDOOR COLD FRONT INTO NRN UT AND SW WY
LATER TONIGHT. THIS WILL TURN THE FLOW TO THE NORTH AND BEGIN
USHERING DRIER AIR INTO THE REGION. AS THE FRONT PUSHES SOUTH THE
PRECIPITATION WILL DIMINISH ACROSS NRN UT ON MONDAY WHILE IT
CONTINUES IN CENTRAL UT THROUGH MUCH OF THE DAY.

THE UPPER LEVEL RIDGE AXIS OFF OF THE WEST COAST SHARPENS
SUBSTANTIALLY AND MOVES OVER THE INTERIOR WEST FOR TUE AND WED
RESULTING IN A PERIOD OF DRY WEATHER OVER THE EASTERN GREAT BASIN
AHEAD ANOTHER APPROACHING COLD FRONT WHICH WILL IMPACT THE REGION
DURING THE LATTER PORTION OF THE WEEK.

WITH THIS UPDATE MADE SOME MINOR ADJUSTMENTS TO THE SNOW
LEVELS...LIMITED HOW MUCH THE SNOW LEVEL RISES THIS AFTERNOON...WHICH
WILL KEEP A MIX OF RAIN AND SNOW IN SOUTHWEST WY THROUGH THE DAY.
ALSO...MADE SOME MINOR ADJUSTMENTS TO THE MAXIMUM TEMPERATURES
ALONG THE WASATCH FRONT AND EAST CENTRAL VALLEYS BASED ON CURRENT
TRENDS. FINALLY...INCREASED WINDS ALONG RIDGETOPS IN NRN UT TO
MATCH EXPECTED GUSTS.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED TO PREVAIL AT THE SLC
TERMINAL DURING THE DAYTIME HOURS WITH CIGS BELOW 6000 FT AGL IN
RAIN. SOME PERIODS OF HIGH-END MVFR CONDITIONS WILL OCCUR IN HEAVIER
RAIN THROUGH THE AFTERNOON. SOUTHEAST WINDS ARE EXPECTED TO SHIFT TO
THE NORTHWEST WITH THE PASSAGE OF A COLD FRONT BETWEEN 00Z AND 02Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.

WY...HIGH WIND WARNING UNTIL 2 AM MST MONDAY FOR WYZ021.

&&

$$

PUBLIC...GRAHAM
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)




000
FXUS65 KSLC 211826
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1126 AM MST SUN DEC 21 2014

.SYNOPSIS...A VERY MILD AND MOIST NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TODAY INTO TONIGHT. A COLD FRONT
WILL MOVE SOUTH ACROSS THE AREA LATE TONIGHT AND MONDAY BRINGING
A COOLER BUT DRIER AIRMASS INTO THE REGION THROUGH WEDNESDAY.

&&

.DISCUSSION...BROAD RIDGE AXIS SITUATED OFF OF THE WEST COAST
PLACING UTAH UNDER STRONG NORTHWEST FLOW. OVER THE TOP OF THE
RIDGE A SIGNIFICANT INLAND PENETRATING ATMOSPHERIC RIVER IS
BRINGING A SUBSTANTIAL AMOUNT OF MOISTURE INTO NORTHERN UTAH AND
SOUTHWEST WYOMING TODAY. THE 1200 UTC KSLC SOUNDING HAD .58"
PRECIPITABLE WATER...WHICH IS 2 STANDARD DEVIATIONS ABOVE NORMAL
FOR THIS TIME OF YEAR. IN ADDITION TO THE SUBSTANTIAL MOISTURE
PLUME...NORTHWEST FLOW ALOFT IS VERY STRONG WITH 80-90 KNOTS OF
FLOW EXPECTED AT 500 HPA OVER NORTHERN UTAH AND SOUTHWEST WYOMING
THIS AFTERNOON. THE COMBINATION OF ANOMALOUSLY DEEP MOISTURE AND
STRONG FLOW POINTS TO AN UNUSUAL EVENT UNDERWAY WITH FORECAST
INTEGRATED WATER VAPOR TRANSPORT VALUES HAVING RETURN INTERVALS OF
ONCE EVERY 20+ YEARS. THE STRONG AND VERY MOIST FLOW IS OCCURRING
IN A MODEST WARM ADVECTION ENVIRONMENT WHICH YIELDS SIGNIFICANT
ISENTROPIC UPGLIDE THROUGH THE EVENING HOURS. WITH THIS IN MIND
EXPECT WIDESPREAD PRECIPITATION TO CONTINUE ACROSS NRN UT AND SW
WY THROUGH THIS EVENING WITH AN INCREASE IN INTENSITY FOR MOST
AREAS.

ALSO...WITH VERY STRONG WIND ALOFT ANTICIPATE THAT HIGH
WINDS..WITH GUSTS TO 60 MPH...WILL DEVELOP ACROSS SW WY TODAY.
ACROSS NRN UT RIDGETOP WINDS MAY BE QUITE SIGNIFICANT WITH THE
HIGHEST EXPOSED PEAKS IN THE WASATCH POTENTIALLY RECEIVING 90+ MPH
WIND GUSTS THIS AFTERNOON AND EVENING. ONGOING WINTER STORM
WARNINGS FOR UTAH/S NORTHERN AND CENTRAL MOUNTAINS LOOK TO BE IN
GOOD SHAPE AS DOES THE HIGH WIND WARNING FOR SOUTHWEST WY. BELIEVE
THAT MOST SIGNIFICANT SNOW AMOUNTS WILL BE IN THE WASATCH RANGE
NORTH OF I-80 WHERE STORM TOTALS OF 24+ INCHES OF SNOW ARE
POSSIBLE...IN THE MOST FAVORED AREAS...BY THE TIME THE STORM WINDS
DOWN ON MONDAY. FURTHER SOUTH...THE 10-20" RANGE STILL LOOKS GOOD
FOR THE WASATCH MOUNTAINS SOUTH OF I-80...ALTHOUGH LOCALLY HIGHER
AMOUNTS WILL BE POSSIBLE ABOVE 8500 FEET.

SNOW LEVELS HAVE BEEN A BIT STUBBORN AND HAVE BEEN SLOW TO RISE
THIS MORNING. HOWEVER...STILL ANTICIPATE THAT THEY WILL RISE THIS
AFTERNOON. HAVE TRENDED THE SNOW LEVELS DOWN A BIT AND NOW
ANTICIPATE THAT THE SNOW LEVEL WILL RISE TO 7000-7500 AGL THIS
AFTERNOON/EVENING.

A SHORTWAVE DROPPING INTO THE BACKSIDE OF A TROUGH IN THE NORTHERN
PLAINS WILL NUDGE A BACKDOOR COLD FRONT INTO NRN UT AND SW WY
LATER TONIGHT. THIS WILL TURN THE FLOW TO THE NORTH AND BEGIN
USHERING DRIER AIR INTO THE REGION. AS THE FRONT PUSHES SOUTH THE
PRECIPITATION WILL DIMINISH ACROSS NRN UT ON MONDAY WHILE IT
CONTINUES IN CENTRAL UT THROUGH MUCH OF THE DAY.

THE UPPER LEVEL RIDGE AXIS OFF OF THE WEST COAST SHARPENS
SUBSTANTIALLY AND MOVES OVER THE INTERIOR WEST FOR TUE AND WED
RESULTING IN A PERIOD OF DRY WEATHER OVER THE EASTERN GREAT BASIN
AHEAD ANOTHER APPROACHING COLD FRONT WHICH WILL IMPACT THE REGION
DURING THE LATTER PORTION OF THE WEEK.

WITH THIS UPDATE MADE SOME MINOR ADJUSTMENTS TO THE SNOW
LEVELS...LIMITED HOW MUCH THE SNOW LEVEL RISES THIS AFTERNOON...WHICH
WILL KEEP A MIX OF RAIN AND SNOW IN SOUTHWEST WY THROUGH THE DAY.
ALSO...MADE SOME MINOR ADJUSTMENTS TO THE MAXIMUM TEMPERATURES
ALONG THE WASATCH FRONT AND EAST CENTRAL VALLEYS BASED ON CURRENT
TRENDS. FINALLY...INCREASED WINDS ALONG RIDGETOPS IN NRN UT TO
MATCH EXPECTED GUSTS.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED TO PREVAIL AT THE SLC
TERMINAL DURING THE DAYTIME HOURS WITH CIGS BELOW 6000 FT AGL IN
RAIN. SOME PERIODS OF HIGH-END MVFR CONDITIONS WILL OCCUR IN HEAVIER
RAIN THROUGH THE AFTERNOON. SOUTHEAST WINDS ARE EXPECTED TO SHIFT TO
THE NORTHWEST WITH THE PASSAGE OF A COLD FRONT BETWEEN 00Z AND 02Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.

WY...HIGH WIND WARNING UNTIL 2 AM MST MONDAY FOR WYZ021.

&&

$$

PUBLIC...GRAHAM
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)




000
FXUS65 KSLC 211826
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1126 AM MST SUN DEC 21 2014

.SYNOPSIS...A VERY MILD AND MOIST NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TODAY INTO TONIGHT. A COLD FRONT
WILL MOVE SOUTH ACROSS THE AREA LATE TONIGHT AND MONDAY BRINGING
A COOLER BUT DRIER AIRMASS INTO THE REGION THROUGH WEDNESDAY.

&&

.DISCUSSION...BROAD RIDGE AXIS SITUATED OFF OF THE WEST COAST
PLACING UTAH UNDER STRONG NORTHWEST FLOW. OVER THE TOP OF THE
RIDGE A SIGNIFICANT INLAND PENETRATING ATMOSPHERIC RIVER IS
BRINGING A SUBSTANTIAL AMOUNT OF MOISTURE INTO NORTHERN UTAH AND
SOUTHWEST WYOMING TODAY. THE 1200 UTC KSLC SOUNDING HAD .58"
PRECIPITABLE WATER...WHICH IS 2 STANDARD DEVIATIONS ABOVE NORMAL
FOR THIS TIME OF YEAR. IN ADDITION TO THE SUBSTANTIAL MOISTURE
PLUME...NORTHWEST FLOW ALOFT IS VERY STRONG WITH 80-90 KNOTS OF
FLOW EXPECTED AT 500 HPA OVER NORTHERN UTAH AND SOUTHWEST WYOMING
THIS AFTERNOON. THE COMBINATION OF ANOMALOUSLY DEEP MOISTURE AND
STRONG FLOW POINTS TO AN UNUSUAL EVENT UNDERWAY WITH FORECAST
INTEGRATED WATER VAPOR TRANSPORT VALUES HAVING RETURN INTERVALS OF
ONCE EVERY 20+ YEARS. THE STRONG AND VERY MOIST FLOW IS OCCURRING
IN A MODEST WARM ADVECTION ENVIRONMENT WHICH YIELDS SIGNIFICANT
ISENTROPIC UPGLIDE THROUGH THE EVENING HOURS. WITH THIS IN MIND
EXPECT WIDESPREAD PRECIPITATION TO CONTINUE ACROSS NRN UT AND SW
WY THROUGH THIS EVENING WITH AN INCREASE IN INTENSITY FOR MOST
AREAS.

ALSO...WITH VERY STRONG WIND ALOFT ANTICIPATE THAT HIGH
WINDS..WITH GUSTS TO 60 MPH...WILL DEVELOP ACROSS SW WY TODAY.
ACROSS NRN UT RIDGETOP WINDS MAY BE QUITE SIGNIFICANT WITH THE
HIGHEST EXPOSED PEAKS IN THE WASATCH POTENTIALLY RECEIVING 90+ MPH
WIND GUSTS THIS AFTERNOON AND EVENING. ONGOING WINTER STORM
WARNINGS FOR UTAH/S NORTHERN AND CENTRAL MOUNTAINS LOOK TO BE IN
GOOD SHAPE AS DOES THE HIGH WIND WARNING FOR SOUTHWEST WY. BELIEVE
THAT MOST SIGNIFICANT SNOW AMOUNTS WILL BE IN THE WASATCH RANGE
NORTH OF I-80 WHERE STORM TOTALS OF 24+ INCHES OF SNOW ARE
POSSIBLE...IN THE MOST FAVORED AREAS...BY THE TIME THE STORM WINDS
DOWN ON MONDAY. FURTHER SOUTH...THE 10-20" RANGE STILL LOOKS GOOD
FOR THE WASATCH MOUNTAINS SOUTH OF I-80...ALTHOUGH LOCALLY HIGHER
AMOUNTS WILL BE POSSIBLE ABOVE 8500 FEET.

SNOW LEVELS HAVE BEEN A BIT STUBBORN AND HAVE BEEN SLOW TO RISE
THIS MORNING. HOWEVER...STILL ANTICIPATE THAT THEY WILL RISE THIS
AFTERNOON. HAVE TRENDED THE SNOW LEVELS DOWN A BIT AND NOW
ANTICIPATE THAT THE SNOW LEVEL WILL RISE TO 7000-7500 AGL THIS
AFTERNOON/EVENING.

A SHORTWAVE DROPPING INTO THE BACKSIDE OF A TROUGH IN THE NORTHERN
PLAINS WILL NUDGE A BACKDOOR COLD FRONT INTO NRN UT AND SW WY
LATER TONIGHT. THIS WILL TURN THE FLOW TO THE NORTH AND BEGIN
USHERING DRIER AIR INTO THE REGION. AS THE FRONT PUSHES SOUTH THE
PRECIPITATION WILL DIMINISH ACROSS NRN UT ON MONDAY WHILE IT
CONTINUES IN CENTRAL UT THROUGH MUCH OF THE DAY.

THE UPPER LEVEL RIDGE AXIS OFF OF THE WEST COAST SHARPENS
SUBSTANTIALLY AND MOVES OVER THE INTERIOR WEST FOR TUE AND WED
RESULTING IN A PERIOD OF DRY WEATHER OVER THE EASTERN GREAT BASIN
AHEAD ANOTHER APPROACHING COLD FRONT WHICH WILL IMPACT THE REGION
DURING THE LATTER PORTION OF THE WEEK.

WITH THIS UPDATE MADE SOME MINOR ADJUSTMENTS TO THE SNOW
LEVELS...LIMITED HOW MUCH THE SNOW LEVEL RISES THIS AFTERNOON...WHICH
WILL KEEP A MIX OF RAIN AND SNOW IN SOUTHWEST WY THROUGH THE DAY.
ALSO...MADE SOME MINOR ADJUSTMENTS TO THE MAXIMUM TEMPERATURES
ALONG THE WASATCH FRONT AND EAST CENTRAL VALLEYS BASED ON CURRENT
TRENDS. FINALLY...INCREASED WINDS ALONG RIDGETOPS IN NRN UT TO
MATCH EXPECTED GUSTS.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED TO PREVAIL AT THE SLC
TERMINAL DURING THE DAYTIME HOURS WITH CIGS BELOW 6000 FT AGL IN
RAIN. SOME PERIODS OF HIGH-END MVFR CONDITIONS WILL OCCUR IN HEAVIER
RAIN THROUGH THE AFTERNOON. SOUTHEAST WINDS ARE EXPECTED TO SHIFT TO
THE NORTHWEST WITH THE PASSAGE OF A COLD FRONT BETWEEN 00Z AND 02Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.

WY...HIGH WIND WARNING UNTIL 2 AM MST MONDAY FOR WYZ021.

&&

$$

PUBLIC...GRAHAM
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)




000
FXUS65 KSLC 211826
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1126 AM MST SUN DEC 21 2014

.SYNOPSIS...A VERY MILD AND MOIST NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TODAY INTO TONIGHT. A COLD FRONT
WILL MOVE SOUTH ACROSS THE AREA LATE TONIGHT AND MONDAY BRINGING
A COOLER BUT DRIER AIRMASS INTO THE REGION THROUGH WEDNESDAY.

&&

.DISCUSSION...BROAD RIDGE AXIS SITUATED OFF OF THE WEST COAST
PLACING UTAH UNDER STRONG NORTHWEST FLOW. OVER THE TOP OF THE
RIDGE A SIGNIFICANT INLAND PENETRATING ATMOSPHERIC RIVER IS
BRINGING A SUBSTANTIAL AMOUNT OF MOISTURE INTO NORTHERN UTAH AND
SOUTHWEST WYOMING TODAY. THE 1200 UTC KSLC SOUNDING HAD .58"
PRECIPITABLE WATER...WHICH IS 2 STANDARD DEVIATIONS ABOVE NORMAL
FOR THIS TIME OF YEAR. IN ADDITION TO THE SUBSTANTIAL MOISTURE
PLUME...NORTHWEST FLOW ALOFT IS VERY STRONG WITH 80-90 KNOTS OF
FLOW EXPECTED AT 500 HPA OVER NORTHERN UTAH AND SOUTHWEST WYOMING
THIS AFTERNOON. THE COMBINATION OF ANOMALOUSLY DEEP MOISTURE AND
STRONG FLOW POINTS TO AN UNUSUAL EVENT UNDERWAY WITH FORECAST
INTEGRATED WATER VAPOR TRANSPORT VALUES HAVING RETURN INTERVALS OF
ONCE EVERY 20+ YEARS. THE STRONG AND VERY MOIST FLOW IS OCCURRING
IN A MODEST WARM ADVECTION ENVIRONMENT WHICH YIELDS SIGNIFICANT
ISENTROPIC UPGLIDE THROUGH THE EVENING HOURS. WITH THIS IN MIND
EXPECT WIDESPREAD PRECIPITATION TO CONTINUE ACROSS NRN UT AND SW
WY THROUGH THIS EVENING WITH AN INCREASE IN INTENSITY FOR MOST
AREAS.

ALSO...WITH VERY STRONG WIND ALOFT ANTICIPATE THAT HIGH
WINDS..WITH GUSTS TO 60 MPH...WILL DEVELOP ACROSS SW WY TODAY.
ACROSS NRN UT RIDGETOP WINDS MAY BE QUITE SIGNIFICANT WITH THE
HIGHEST EXPOSED PEAKS IN THE WASATCH POTENTIALLY RECEIVING 90+ MPH
WIND GUSTS THIS AFTERNOON AND EVENING. ONGOING WINTER STORM
WARNINGS FOR UTAH/S NORTHERN AND CENTRAL MOUNTAINS LOOK TO BE IN
GOOD SHAPE AS DOES THE HIGH WIND WARNING FOR SOUTHWEST WY. BELIEVE
THAT MOST SIGNIFICANT SNOW AMOUNTS WILL BE IN THE WASATCH RANGE
NORTH OF I-80 WHERE STORM TOTALS OF 24+ INCHES OF SNOW ARE
POSSIBLE...IN THE MOST FAVORED AREAS...BY THE TIME THE STORM WINDS
DOWN ON MONDAY. FURTHER SOUTH...THE 10-20" RANGE STILL LOOKS GOOD
FOR THE WASATCH MOUNTAINS SOUTH OF I-80...ALTHOUGH LOCALLY HIGHER
AMOUNTS WILL BE POSSIBLE ABOVE 8500 FEET.

SNOW LEVELS HAVE BEEN A BIT STUBBORN AND HAVE BEEN SLOW TO RISE
THIS MORNING. HOWEVER...STILL ANTICIPATE THAT THEY WILL RISE THIS
AFTERNOON. HAVE TRENDED THE SNOW LEVELS DOWN A BIT AND NOW
ANTICIPATE THAT THE SNOW LEVEL WILL RISE TO 7000-7500 AGL THIS
AFTERNOON/EVENING.

A SHORTWAVE DROPPING INTO THE BACKSIDE OF A TROUGH IN THE NORTHERN
PLAINS WILL NUDGE A BACKDOOR COLD FRONT INTO NRN UT AND SW WY
LATER TONIGHT. THIS WILL TURN THE FLOW TO THE NORTH AND BEGIN
USHERING DRIER AIR INTO THE REGION. AS THE FRONT PUSHES SOUTH THE
PRECIPITATION WILL DIMINISH ACROSS NRN UT ON MONDAY WHILE IT
CONTINUES IN CENTRAL UT THROUGH MUCH OF THE DAY.

THE UPPER LEVEL RIDGE AXIS OFF OF THE WEST COAST SHARPENS
SUBSTANTIALLY AND MOVES OVER THE INTERIOR WEST FOR TUE AND WED
RESULTING IN A PERIOD OF DRY WEATHER OVER THE EASTERN GREAT BASIN
AHEAD ANOTHER APPROACHING COLD FRONT WHICH WILL IMPACT THE REGION
DURING THE LATTER PORTION OF THE WEEK.

WITH THIS UPDATE MADE SOME MINOR ADJUSTMENTS TO THE SNOW
LEVELS...LIMITED HOW MUCH THE SNOW LEVEL RISES THIS AFTERNOON...WHICH
WILL KEEP A MIX OF RAIN AND SNOW IN SOUTHWEST WY THROUGH THE DAY.
ALSO...MADE SOME MINOR ADJUSTMENTS TO THE MAXIMUM TEMPERATURES
ALONG THE WASATCH FRONT AND EAST CENTRAL VALLEYS BASED ON CURRENT
TRENDS. FINALLY...INCREASED WINDS ALONG RIDGETOPS IN NRN UT TO
MATCH EXPECTED GUSTS.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED TO PREVAIL AT THE SLC
TERMINAL DURING THE DAYTIME HOURS WITH CIGS BELOW 6000 FT AGL IN
RAIN. SOME PERIODS OF HIGH-END MVFR CONDITIONS WILL OCCUR IN HEAVIER
RAIN THROUGH THE AFTERNOON. SOUTHEAST WINDS ARE EXPECTED TO SHIFT TO
THE NORTHWEST WITH THE PASSAGE OF A COLD FRONT BETWEEN 00Z AND 02Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.

WY...HIGH WIND WARNING UNTIL 2 AM MST MONDAY FOR WYZ021.

&&

$$

PUBLIC...GRAHAM
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)




000
FXUS65 KSLC 211301
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
601 AM MST SUN DEC 21 2014

.SYNOPSIS...A VERY MILD AND MOIST NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TODAY INTO TONIGHT. A COLD FRONT
WILL MOVE SOUTH ACROSS THE AREA LATE TONIGHT AND MONDAY BRINGING
A COOLER BUT DRIER AIRMASS.

&&

.SHORT TERM (THRU 00Z THU)...THE VERY MOIST NORTHWEST FLOW EVENT
IS UNDER WAY AND EXPECT CONSIDERABLE WATER AMOUNTS TO FALL ACROSS
THE NORTHERN MOUNTAINS AND ADJACENT UPSTREAM VALLEYS THRU TONIGHT.

SNOW LEVELS HAVE NOT RISEN MUCH YET THIS MORNING WITH IMPACTS ON
TRAVEL ON THE MAJOR MOUNTAIN PASSES AS WELL AS IN THE HIGHER
WASATCH MOUNTAIN VALLEYS AROUND PARK CITY. THIS SHOULD END BY
MIDDAY AS SNOW LEVELS RISE.

A COLD FRONT IS STILL FORECAST TO CROSS THE CWA FROM THE NORTH
AFTER MIDNIGHT TONIGHT THRU MIDDAY MON. MODELS DO SHOW PRECIP OVER
THE NORTH WINDING DOWN BEHIND THIS FRONT BUT COULD SEE SHOWERY
PRECIP CONTINUE THRU THE DAY MON. THE HEAVIEST PRECIP DOES SHIFT
SOUTH WITH THIS FRONT INTO THE CENTRAL MTNS. WATER AMOUNTS WILL
BE LESS THAN OVER THE NORTH BUT THERE SHOULD STILL BE ENOUGH
IMPACT ON THE HIGHER ELEVATIONS COMBINED WITH WIND TO KEEP THE
EXISTING WARNING.

THE WINDS SHOULD GET STRONG ACROSS WY AS WELL TODAY LASTING THRU
TONIGHT AND THE CURRENT WIND WARNING WILL REMAIN IN PLACE. PRECIP
HAS ALSO BEGUN AS SNOW HERE TOO AND THIS WILL CREATE LOCAL HAZARDOUS
TRAVEL UNTIL MID MORNING WHEN SNOW LEVELS RISE.

THE EVENT SHOULD END BY MON EVE WITH DRY COLD NORTHERLY FLOW MON
NIGHT INTO TUE. THE UPSTREAM RIDGE ADVANCES AND PROMOTES
INVERSION DEVELOPMENT FOR TUE INTO WED. THE FLOW INCREASES OUT OF
THE WSW LATER WED AHEAD OF THE NEXT PAC TROF.

&&

.LONG TERM (AFTER 00Z THURSDAY)...PACIFIC TROUGH SPEEDS TOWARD UTAH
FROM THE NORTHWEST...BRINGING COLDER AIR AND PRECIPITATION TO
NORTHERN AND CENTRAL UTAH PRIMARILY ON CHRISTMAS DAY. MODEL
AGREEMENT MOVING A BIT MORE IN LINE AS THE ECMWF SOLUTION NUDGES
TOWARD THE GFS IN WEAKENING THE DURATION AND IMPACT OF THE
STORM...WITH 700 MB TEMPERATURES MATCHING UP AT A LOW OF 15C. LATEST
GFS RUN HAS SLOWED THE INTRODUCTION OF PRECIPITATION INTO THE
REGION...WAITING TILL FOLKS ARE SETTLED IN AT GRANDMAS HOUSE LATE
WEDNESDAY EVENING. COLD FRONT CROSSING MUCH OF THE AREA DURING
CHRISTMAS DAY BRINGING SNOW TO THE MOUNTAINS SOME VALLEY LOCATIONS.
LOWERED VALLEY POPS A BIT FOR THURSDAY AND KEPT THEM IN FOR
LINGERING SNOW SHOWERS IN THE HIGHER NORTHERN UTAH TERRAIN INTO
FRIDAY. RIDGING BUILDS RAPIDLY AS THE SYSTEM EXITS FRIDAY INTO
SATURDAY.

&&

.AVIATION...MVFR CEILINGS IN RAIN WILL PREVAIL AT THE SLC
TERMINAL THROUGH MOST OF THE DAY. THERE IS A 40 PERCENT CHANCE OF
MVFR VSBY AS WELL DURING THIS PERIOD. SOUTHERLY SURFACE WINDS WILL
CONTINUE THROUGH THE DAY AND COULD BE OCCASIONALLY GUSTY.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.

WY...HIGH WIND WARNING UNTIL 2 AM MST MONDAY FOR WYZ021.

&&

$$

SHORT TERM/AVIATION...WILENSKY
LONG TERM...VERZELLA

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)



000
FXUS65 KSLC 211301
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
601 AM MST SUN DEC 21 2014

.SYNOPSIS...A VERY MILD AND MOIST NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TODAY INTO TONIGHT. A COLD FRONT
WILL MOVE SOUTH ACROSS THE AREA LATE TONIGHT AND MONDAY BRINGING
A COOLER BUT DRIER AIRMASS.

&&

.SHORT TERM (THRU 00Z THU)...THE VERY MOIST NORTHWEST FLOW EVENT
IS UNDER WAY AND EXPECT CONSIDERABLE WATER AMOUNTS TO FALL ACROSS
THE NORTHERN MOUNTAINS AND ADJACENT UPSTREAM VALLEYS THRU TONIGHT.

SNOW LEVELS HAVE NOT RISEN MUCH YET THIS MORNING WITH IMPACTS ON
TRAVEL ON THE MAJOR MOUNTAIN PASSES AS WELL AS IN THE HIGHER
WASATCH MOUNTAIN VALLEYS AROUND PARK CITY. THIS SHOULD END BY
MIDDAY AS SNOW LEVELS RISE.

A COLD FRONT IS STILL FORECAST TO CROSS THE CWA FROM THE NORTH
AFTER MIDNIGHT TONIGHT THRU MIDDAY MON. MODELS DO SHOW PRECIP OVER
THE NORTH WINDING DOWN BEHIND THIS FRONT BUT COULD SEE SHOWERY
PRECIP CONTINUE THRU THE DAY MON. THE HEAVIEST PRECIP DOES SHIFT
SOUTH WITH THIS FRONT INTO THE CENTRAL MTNS. WATER AMOUNTS WILL
BE LESS THAN OVER THE NORTH BUT THERE SHOULD STILL BE ENOUGH
IMPACT ON THE HIGHER ELEVATIONS COMBINED WITH WIND TO KEEP THE
EXISTING WARNING.

THE WINDS SHOULD GET STRONG ACROSS WY AS WELL TODAY LASTING THRU
TONIGHT AND THE CURRENT WIND WARNING WILL REMAIN IN PLACE. PRECIP
HAS ALSO BEGUN AS SNOW HERE TOO AND THIS WILL CREATE LOCAL HAZARDOUS
TRAVEL UNTIL MID MORNING WHEN SNOW LEVELS RISE.

THE EVENT SHOULD END BY MON EVE WITH DRY COLD NORTHERLY FLOW MON
NIGHT INTO TUE. THE UPSTREAM RIDGE ADVANCES AND PROMOTES
INVERSION DEVELOPMENT FOR TUE INTO WED. THE FLOW INCREASES OUT OF
THE WSW LATER WED AHEAD OF THE NEXT PAC TROF.

&&

.LONG TERM (AFTER 00Z THURSDAY)...PACIFIC TROUGH SPEEDS TOWARD UTAH
FROM THE NORTHWEST...BRINGING COLDER AIR AND PRECIPITATION TO
NORTHERN AND CENTRAL UTAH PRIMARILY ON CHRISTMAS DAY. MODEL
AGREEMENT MOVING A BIT MORE IN LINE AS THE ECMWF SOLUTION NUDGES
TOWARD THE GFS IN WEAKENING THE DURATION AND IMPACT OF THE
STORM...WITH 700 MB TEMPERATURES MATCHING UP AT A LOW OF 15C. LATEST
GFS RUN HAS SLOWED THE INTRODUCTION OF PRECIPITATION INTO THE
REGION...WAITING TILL FOLKS ARE SETTLED IN AT GRANDMAS HOUSE LATE
WEDNESDAY EVENING. COLD FRONT CROSSING MUCH OF THE AREA DURING
CHRISTMAS DAY BRINGING SNOW TO THE MOUNTAINS SOME VALLEY LOCATIONS.
LOWERED VALLEY POPS A BIT FOR THURSDAY AND KEPT THEM IN FOR
LINGERING SNOW SHOWERS IN THE HIGHER NORTHERN UTAH TERRAIN INTO
FRIDAY. RIDGING BUILDS RAPIDLY AS THE SYSTEM EXITS FRIDAY INTO
SATURDAY.

&&

.AVIATION...MVFR CEILINGS IN RAIN WILL PREVAIL AT THE SLC
TERMINAL THROUGH MOST OF THE DAY. THERE IS A 40 PERCENT CHANCE OF
MVFR VSBY AS WELL DURING THIS PERIOD. SOUTHERLY SURFACE WINDS WILL
CONTINUE THROUGH THE DAY AND COULD BE OCCASIONALLY GUSTY.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.

WY...HIGH WIND WARNING UNTIL 2 AM MST MONDAY FOR WYZ021.

&&

$$

SHORT TERM/AVIATION...WILENSKY
LONG TERM...VERZELLA

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)



000
FXUS65 KSLC 211301
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
601 AM MST SUN DEC 21 2014

.SYNOPSIS...A VERY MILD AND MOIST NORTHWEST FLOW WILL CONTINUE
ACROSS NORTHERN AND CENTRAL UTAH TODAY INTO TONIGHT. A COLD FRONT
WILL MOVE SOUTH ACROSS THE AREA LATE TONIGHT AND MONDAY BRINGING
A COOLER BUT DRIER AIRMASS.

&&

.SHORT TERM (THRU 00Z THU)...THE VERY MOIST NORTHWEST FLOW EVENT
IS UNDER WAY AND EXPECT CONSIDERABLE WATER AMOUNTS TO FALL ACROSS
THE NORTHERN MOUNTAINS AND ADJACENT UPSTREAM VALLEYS THRU TONIGHT.

SNOW LEVELS HAVE NOT RISEN MUCH YET THIS MORNING WITH IMPACTS ON
TRAVEL ON THE MAJOR MOUNTAIN PASSES AS WELL AS IN THE HIGHER
WASATCH MOUNTAIN VALLEYS AROUND PARK CITY. THIS SHOULD END BY
MIDDAY AS SNOW LEVELS RISE.

A COLD FRONT IS STILL FORECAST TO CROSS THE CWA FROM THE NORTH
AFTER MIDNIGHT TONIGHT THRU MIDDAY MON. MODELS DO SHOW PRECIP OVER
THE NORTH WINDING DOWN BEHIND THIS FRONT BUT COULD SEE SHOWERY
PRECIP CONTINUE THRU THE DAY MON. THE HEAVIEST PRECIP DOES SHIFT
SOUTH WITH THIS FRONT INTO THE CENTRAL MTNS. WATER AMOUNTS WILL
BE LESS THAN OVER THE NORTH BUT THERE SHOULD STILL BE ENOUGH
IMPACT ON THE HIGHER ELEVATIONS COMBINED WITH WIND TO KEEP THE
EXISTING WARNING.

THE WINDS SHOULD GET STRONG ACROSS WY AS WELL TODAY LASTING THRU
TONIGHT AND THE CURRENT WIND WARNING WILL REMAIN IN PLACE. PRECIP
HAS ALSO BEGUN AS SNOW HERE TOO AND THIS WILL CREATE LOCAL HAZARDOUS
TRAVEL UNTIL MID MORNING WHEN SNOW LEVELS RISE.

THE EVENT SHOULD END BY MON EVE WITH DRY COLD NORTHERLY FLOW MON
NIGHT INTO TUE. THE UPSTREAM RIDGE ADVANCES AND PROMOTES
INVERSION DEVELOPMENT FOR TUE INTO WED. THE FLOW INCREASES OUT OF
THE WSW LATER WED AHEAD OF THE NEXT PAC TROF.

&&

.LONG TERM (AFTER 00Z THURSDAY)...PACIFIC TROUGH SPEEDS TOWARD UTAH
FROM THE NORTHWEST...BRINGING COLDER AIR AND PRECIPITATION TO
NORTHERN AND CENTRAL UTAH PRIMARILY ON CHRISTMAS DAY. MODEL
AGREEMENT MOVING A BIT MORE IN LINE AS THE ECMWF SOLUTION NUDGES
TOWARD THE GFS IN WEAKENING THE DURATION AND IMPACT OF THE
STORM...WITH 700 MB TEMPERATURES MATCHING UP AT A LOW OF 15C. LATEST
GFS RUN HAS SLOWED THE INTRODUCTION OF PRECIPITATION INTO THE
REGION...WAITING TILL FOLKS ARE SETTLED IN AT GRANDMAS HOUSE LATE
WEDNESDAY EVENING. COLD FRONT CROSSING MUCH OF THE AREA DURING
CHRISTMAS DAY BRINGING SNOW TO THE MOUNTAINS SOME VALLEY LOCATIONS.
LOWERED VALLEY POPS A BIT FOR THURSDAY AND KEPT THEM IN FOR
LINGERING SNOW SHOWERS IN THE HIGHER NORTHERN UTAH TERRAIN INTO
FRIDAY. RIDGING BUILDS RAPIDLY AS THE SYSTEM EXITS FRIDAY INTO
SATURDAY.

&&

.AVIATION...MVFR CEILINGS IN RAIN WILL PREVAIL AT THE SLC
TERMINAL THROUGH MOST OF THE DAY. THERE IS A 40 PERCENT CHANCE OF
MVFR VSBY AS WELL DURING THIS PERIOD. SOUTHERLY SURFACE WINDS WILL
CONTINUE THROUGH THE DAY AND COULD BE OCCASIONALLY GUSTY.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.

WY...HIGH WIND WARNING UNTIL 2 AM MST MONDAY FOR WYZ021.

&&

$$

SHORT TERM/AVIATION...WILENSKY
LONG TERM...VERZELLA

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)




000
FXUS65 KSLC 210515
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1015 PM MST SAT DEC 20 2014

.SYNOPSIS...A VERY WARM AND MOIST STREAM OF PACIFIC AIR EXTENDS
FROM THE PACIFIC NORTHWEST INTO NORTHERN UTAH. THIS WILL CONTINUE
INTO MONDAY. A COLD FRONT WILL MOVE THROUGH THE AREA FROM NORTH
TO SOUTH ON MONDAY BRINGING A COOLER BUT DRIER AIRMASS.

&&

.DISCUSSION...AN ANOMALOUSLY MOIST AIRMASS OWING TO AN ATMOSPHERIC
RIVER PENETRATING THE PACIFIC NORTHWEST AND TAKING AIM AT NORTHERN
UTAH IS STILL ON TRACK TO PROVIDE COPIOUS PRECIPITATION TO MUCH OF
NORTHERN UTAH AND THE CENTRAL UTAH MOUNTAINS. PRECIPITATION IS
BEGINNING TO FILL IN OVER NORTHERN UTAH THIS EVENING AS WARM
ADVECTION BEGINS. HEAVIER PRECIPITATION IS EXPECTED LATE TONIGHT
INTO TOMORROW MORNING AS WARM ADVECTION MAXES OUT...THEN CONTINUE IN
EARNEST THROUGH EARLY TOMORROW EVENING AS MOISTURE CONTINUES TO
INCREASE AS A STRONG UPPER JET NOSES INTO NORTHERN UTAH.
PRECIPITATION WILL LINGER TOMORROW NIGHT BEFORE DRIER AIR SPREADS
INTO THE AREA BEHIND A COLD FRONT MONDAY. MODELS ARE A BIT FASTER
WITH THE DRIER AIR WHICH COULD SHUT OFF THE PRECIPITATION ACROSS
NORTHERN UTAH A BIT EARLIER THAN EXPECTED. HOWEVER...SOME OF THE
MOISTURE WILL GET SHUNTED OFF TO THE SOUTH SO CENTRAL UTAH COULD BE
ACTIVE THROUGH THE DAY MONDAY.

MODELS ARE STILL INDICATING STORM TOTAL QPF OVER 2 INCHES FOR THE
NORTHERN MOUNTAINS WHICH EVEN WITH HIGH-DENSITY SNOW WOULD STILL
LEAD TO SIGNIFICANT ACCUMULATIONS. SNOW LEVELS WILL BE FAIRLY HIGH
FOR MUCH OF THE STORM...KEEPING ACCUMULATING SNOW LIMITED TO THE
HIGH ELEVATIONS. TEMPERATURES TONIGHT SHOULD PRETTY MUCH FLATLINE OR
PERHAPS RISE A BIT THROUGH THE REST OF THE NIGHT ACROSS THE NORTH
DUE TO THICKENING CLOUDS. ALTHOUGH OVERNIGHT MINS ACROSS THE LOWER
VALLEYS OF NORTHERN UTAH ARE FORECAST TO REMAIN ABOVE
FREEZING...CONCERNED THAT WITH SOME BELOW OR NEAR-FREEZING
DEWPOINTS...THERE IS STILL A CHANCE FOR SNOW IN A FEW SPOTS TONIGHT.
ELKO NV MANAGED SO SNOW BRIEFLY AND NAM BUFR SOUNDINGS INDICATE SNOW
FOR MUCH OF THE NIGHT AT LOGAN...ALTHOUGH THIS IS LIKELY OVERDONE.
STILL...HAVE ADJUSTED THE FORECAST TO BRING SNOW WORDING TO A FEW
ZONES TONIGHT. SNOW LEVELS WILL ALSO LOWER ON MONDAY BEHIND THE
FRONT...WITH A POTENTIAL FOR BRIEF VALLEY SNOW AT THE TAIL END OF
THE EVENT.

BESIDES PRECIPITATION...WIND WILL ALSO BE A MAJOR PLAYER IN THIS
EVENT. STRONGEST WINDS WILL BE ACROSS THE HIGHER ELEVATIONS...WHICH
WILL LEAD TO REDUCED VISIBILITIES IN BLOWING SNOW. WINDS AT 700MB
MAX OUT TOMORROW AROUND 50KT TOMORROW...NEAR 60KT ACROSS SOUTHWEST
WYOMING. HOWEVER...500MB WINDS CONTINUE TO INCREASE THROUGH MONDAY
WITH GFS AND NAM SHOWING A RELATIVELY LARGE SWATH OF 100KT OVER
UTAH. EXPOSED AREAS ALONG THE HIGH PEAKS COULD SEE VERY STRONG GUSTS
LATE SUNDAY NIGHT INTO MONDAY AS A RESULT.

EXISTING WINTER STORM AND HIGH WIND WARNINGS REMAIN IN EFFECT.

&&

.AVIATION...CEILINGS AT THE SLC TERMINAL WILL REMAIN AT OR BELOW
6000FT AGL THROUGH THE NIGHT AS RAIN DEVELOPS ACROSS THE AREA. EXPECT
MOSTLY VFR CONDITIONS BUT PERIODIC MVFR CONDITIONS IN HEAVIER RAIN
ARE EXPECTED TO DEVELOP AFTER 10Z AND CONTINUE THROUGH MUCH OF
SUNDAY. SOUTHERLY SURFACE WINDS ARE EXPECTED TO INCREASE THROUGH THE
NIGHT.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.

WY...HIGH WIND WARNING FROM 5 AM SUNDAY TO 2 AM MST MONDAY FOR WYZ021.

&&

$$

CHENG

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)



000
FXUS65 KSLC 210515
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1015 PM MST SAT DEC 20 2014

.SYNOPSIS...A VERY WARM AND MOIST STREAM OF PACIFIC AIR EXTENDS
FROM THE PACIFIC NORTHWEST INTO NORTHERN UTAH. THIS WILL CONTINUE
INTO MONDAY. A COLD FRONT WILL MOVE THROUGH THE AREA FROM NORTH
TO SOUTH ON MONDAY BRINGING A COOLER BUT DRIER AIRMASS.

&&

.DISCUSSION...AN ANOMALOUSLY MOIST AIRMASS OWING TO AN ATMOSPHERIC
RIVER PENETRATING THE PACIFIC NORTHWEST AND TAKING AIM AT NORTHERN
UTAH IS STILL ON TRACK TO PROVIDE COPIOUS PRECIPITATION TO MUCH OF
NORTHERN UTAH AND THE CENTRAL UTAH MOUNTAINS. PRECIPITATION IS
BEGINNING TO FILL IN OVER NORTHERN UTAH THIS EVENING AS WARM
ADVECTION BEGINS. HEAVIER PRECIPITATION IS EXPECTED LATE TONIGHT
INTO TOMORROW MORNING AS WARM ADVECTION MAXES OUT...THEN CONTINUE IN
EARNEST THROUGH EARLY TOMORROW EVENING AS MOISTURE CONTINUES TO
INCREASE AS A STRONG UPPER JET NOSES INTO NORTHERN UTAH.
PRECIPITATION WILL LINGER TOMORROW NIGHT BEFORE DRIER AIR SPREADS
INTO THE AREA BEHIND A COLD FRONT MONDAY. MODELS ARE A BIT FASTER
WITH THE DRIER AIR WHICH COULD SHUT OFF THE PRECIPITATION ACROSS
NORTHERN UTAH A BIT EARLIER THAN EXPECTED. HOWEVER...SOME OF THE
MOISTURE WILL GET SHUNTED OFF TO THE SOUTH SO CENTRAL UTAH COULD BE
ACTIVE THROUGH THE DAY MONDAY.

MODELS ARE STILL INDICATING STORM TOTAL QPF OVER 2 INCHES FOR THE
NORTHERN MOUNTAINS WHICH EVEN WITH HIGH-DENSITY SNOW WOULD STILL
LEAD TO SIGNIFICANT ACCUMULATIONS. SNOW LEVELS WILL BE FAIRLY HIGH
FOR MUCH OF THE STORM...KEEPING ACCUMULATING SNOW LIMITED TO THE
HIGH ELEVATIONS. TEMPERATURES TONIGHT SHOULD PRETTY MUCH FLATLINE OR
PERHAPS RISE A BIT THROUGH THE REST OF THE NIGHT ACROSS THE NORTH
DUE TO THICKENING CLOUDS. ALTHOUGH OVERNIGHT MINS ACROSS THE LOWER
VALLEYS OF NORTHERN UTAH ARE FORECAST TO REMAIN ABOVE
FREEZING...CONCERNED THAT WITH SOME BELOW OR NEAR-FREEZING
DEWPOINTS...THERE IS STILL A CHANCE FOR SNOW IN A FEW SPOTS TONIGHT.
ELKO NV MANAGED SO SNOW BRIEFLY AND NAM BUFR SOUNDINGS INDICATE SNOW
FOR MUCH OF THE NIGHT AT LOGAN...ALTHOUGH THIS IS LIKELY OVERDONE.
STILL...HAVE ADJUSTED THE FORECAST TO BRING SNOW WORDING TO A FEW
ZONES TONIGHT. SNOW LEVELS WILL ALSO LOWER ON MONDAY BEHIND THE
FRONT...WITH A POTENTIAL FOR BRIEF VALLEY SNOW AT THE TAIL END OF
THE EVENT.

BESIDES PRECIPITATION...WIND WILL ALSO BE A MAJOR PLAYER IN THIS
EVENT. STRONGEST WINDS WILL BE ACROSS THE HIGHER ELEVATIONS...WHICH
WILL LEAD TO REDUCED VISIBILITIES IN BLOWING SNOW. WINDS AT 700MB
MAX OUT TOMORROW AROUND 50KT TOMORROW...NEAR 60KT ACROSS SOUTHWEST
WYOMING. HOWEVER...500MB WINDS CONTINUE TO INCREASE THROUGH MONDAY
WITH GFS AND NAM SHOWING A RELATIVELY LARGE SWATH OF 100KT OVER
UTAH. EXPOSED AREAS ALONG THE HIGH PEAKS COULD SEE VERY STRONG GUSTS
LATE SUNDAY NIGHT INTO MONDAY AS A RESULT.

EXISTING WINTER STORM AND HIGH WIND WARNINGS REMAIN IN EFFECT.

&&

.AVIATION...CEILINGS AT THE SLC TERMINAL WILL REMAIN AT OR BELOW
6000FT AGL THROUGH THE NIGHT AS RAIN DEVELOPS ACROSS THE AREA. EXPECT
MOSTLY VFR CONDITIONS BUT PERIODIC MVFR CONDITIONS IN HEAVIER RAIN
ARE EXPECTED TO DEVELOP AFTER 10Z AND CONTINUE THROUGH MUCH OF
SUNDAY. SOUTHERLY SURFACE WINDS ARE EXPECTED TO INCREASE THROUGH THE
NIGHT.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST MONDAY FOR UTZ007>010-517.

WY...HIGH WIND WARNING FROM 5 AM SUNDAY TO 2 AM MST MONDAY FOR WYZ021.

&&

$$

CHENG

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)




000
FXUS65 KSLC 202220
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
320 PM MST SAT DEC 20 2014

.SYNOPSIS...A VERY WARM AND MOIST STREAM OF PACIFIC AIR EXTENDS
FROM THE PACIFIC NORTHWEST INTO NORTHERN UTAH. THIS WILL CONTINUE
INTO MONDAY. A COLD FRONT WILL MOVE THROUGH THE AREA FROM NORTH
TO SOUTH ON MONDAY BRINGING A COOLER BUT DRIER AIRMASS.

&&

.DISCUSSION...THERE WAS NOT MUCH OF A BREAK BETWEEN THE REMNANT
INSTABILITY SHOWERS FROM LAST NIGHTS COLD FRONT AND TROUGH AND THE
BEGINNING OF THE ATMOSPHERIC RIVER EVENT THAT STARTED LATE THIS
MORNING. A WELL DEFINED ATMOSPHERIC RIVER STRETCHES FROM NEAR THE
DATELINE THROUGH OREGON AND THEN SOUTHEAST INTO THE GREAT BASIN.
AS THE EVENT UNFOLDS THE AIRMASS WILL BECOME MORE
MOIST...WARMER...AND THE WINDS WILL INCREASE IN STRENGTH.
PRECIPITABLE WATER VALUES RISE TO AROUND .70 INCHES...700 MB TEMPS
OVER THE NORTH RISE TO 1.5 C AND THE UPPER JET COMES RIGHT OVER
TOP OF THE AREA.

12Z GFS/NAM BOTH GENERATE STORM TOTAL QPF AROUND 2.5-2.9 INCHES IN
THE MOUNTAINS WITH NEARLY AN INCH IN NORTHERN VALLEYS WITH THE
12Z EC A BIT LESS. MODELS HAVE BEEN QUITE CONSISTENT FOR A NUMBER
OF DAYS SO ALTHOUGH IT IS A BIT UNUSUAL FOR UTAH TO SEE SO MUCH
PRECIP FROM A NORTHWEST FLOW WARM AIR ADVECTION EVENT LIKE
THIS...FORECAST CONFIDENCE IS ABOVE AVERAGE.

AS THE TROUGH AT THE WEST END OF THE ATMOSPHERIC RIVER FINALLY
CRESTS THE FLAT RIDGE OVER THE WEST AND PLUNGES INTO THE CENTRAL
U.S. A BACKDOOR COLD FRONT PUSHES FROM NORTH TO SOUTH THROUGH UTAH
ON MONDAY. THIS FRONTAL PASSAGE MARKS THE END OF THE EVENT AS A
MUCH COOLER AND DRIER AIRMASS SPREADS SOUTH THROUGH THE AREA.

FROM SUNDAY NIGHT THROUGH MONDAY EVENING THE WINDS ALOFT ARE VERY
STRONG. RIDGETOP GUSTS AT THE 11K ELEVATION COULD REACH 100 MPH
FROM SUNDAY NIGHT THROUGH MONDAY. THE COMBINATION OF THE VERY WET
DENSE SNOW AND THE HIGH WINDS IS GOING TO CREATE A HIGH AVALANCHE
HAZARD IN THE BACKCOUNTRY. COORDINATING WITH UAFC ON UPGRADING
THEIR AVALANCHE WATCH TO A WARNING THIS AFTERNOON.

PRETTY QUIET MONDAY NIGHT THROUGH EARLY WEDNESDAY. THE MODELS KEEP
GOING BACK AND FORTH ON THE DEPTH AND STRENGTH OF THE CHRISTMAS
STORM. THE KEY SEEMS TO BE HOW THEY HANDLE THE SPLITTING OF A
TROUGH NEAR 150W ON TUESDAY. THE EC KEEPS THE SOUTHERN PORTION OF
THE SPLIT NEAR OR WEST OF 150W WHILE THE GFS PUTS THE SOUTHERN
PORTION EAST OF 150W. THE REASON THIS IS IMPORTANT IS BECAUSE OF
THE LOCATION OF THE RIDGE THAT FORMS JUST DOWNSTREAM OF THIS
CLOSED LOW ON WEDNESDAY. WITH THE RIDGE FURTHER EAST IN THE
GFS...THE CHRISTMAS STORM TENDS TO BE SHUNTED FURTHER EAST WHILE
THE EC RIDGE POSITION ALLOWS THE STORM TO DIG MORE INTO THE GREAT
BASIN. TODAYS 12Z GFS/EC WERE PRETTY CLOSE WITH THE EC SLIGHTLY
COLDER/DEEPER. QUICK LOOK AT THE 18Z GFS SHOWS IT WANDERING BACK
TO THE WEAKER SOLUTION THAT WE SAW FROM THE 00Z AND 06Z GFS RUNS.
STAY TUNED.

BEYOND THURSDAY MODELS DIVERGE CONSIDERABLY ON DETAILS AND
FORECAST CONFIDENCE IS LOW.

&&

.AVIATION...CEILINGS AT THE SLC TERMINAL ARE EXPECTED TO REMAIN AT
OR BELOW 7000 FEET AGL THROUGH THE AFTERNOON AND EVENING. VFR
CONDITIONS AND ISOLATED LIGHT RAIN SHOWERS POSSIBLE AT TIMES
THROUGH THE PERIOD. THERE WILL BE A 50 PERCENT CHANCE OF MVFR
CONDITIONS DUE TO LOWERING CEILINGS IN HEAVIER RAIN SHOWERS AFTER
00Z. GENERALLY LIGHT SOUTHERLY SURFACE WINDS ARE
EXPECTED...ALTHOUGH ERRATIC WINDS ARE POSSIBLE IN SOME HEAVIER
SHOWERS.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM MST MONDAY
     FOR UTZ007>010-517.

WY...HIGH WIND WARNING FROM 5 AM SUNDAY TO 2 AM MST MONDAY FOR WYZ021.

&&

$$

PUBLIC...DUNN
AVIATION...YOUNG

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)



000
FXUS65 KSLC 202220
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
320 PM MST SAT DEC 20 2014

.SYNOPSIS...A VERY WARM AND MOIST STREAM OF PACIFIC AIR EXTENDS
FROM THE PACIFIC NORTHWEST INTO NORTHERN UTAH. THIS WILL CONTINUE
INTO MONDAY. A COLD FRONT WILL MOVE THROUGH THE AREA FROM NORTH
TO SOUTH ON MONDAY BRINGING A COOLER BUT DRIER AIRMASS.

&&

.DISCUSSION...THERE WAS NOT MUCH OF A BREAK BETWEEN THE REMNANT
INSTABILITY SHOWERS FROM LAST NIGHTS COLD FRONT AND TROUGH AND THE
BEGINNING OF THE ATMOSPHERIC RIVER EVENT THAT STARTED LATE THIS
MORNING. A WELL DEFINED ATMOSPHERIC RIVER STRETCHES FROM NEAR THE
DATELINE THROUGH OREGON AND THEN SOUTHEAST INTO THE GREAT BASIN.
AS THE EVENT UNFOLDS THE AIRMASS WILL BECOME MORE
MOIST...WARMER...AND THE WINDS WILL INCREASE IN STRENGTH.
PRECIPITABLE WATER VALUES RISE TO AROUND .70 INCHES...700 MB TEMPS
OVER THE NORTH RISE TO 1.5 C AND THE UPPER JET COMES RIGHT OVER
TOP OF THE AREA.

12Z GFS/NAM BOTH GENERATE STORM TOTAL QPF AROUND 2.5-2.9 INCHES IN
THE MOUNTAINS WITH NEARLY AN INCH IN NORTHERN VALLEYS WITH THE
12Z EC A BIT LESS. MODELS HAVE BEEN QUITE CONSISTENT FOR A NUMBER
OF DAYS SO ALTHOUGH IT IS A BIT UNUSUAL FOR UTAH TO SEE SO MUCH
PRECIP FROM A NORTHWEST FLOW WARM AIR ADVECTION EVENT LIKE
THIS...FORECAST CONFIDENCE IS ABOVE AVERAGE.

AS THE TROUGH AT THE WEST END OF THE ATMOSPHERIC RIVER FINALLY
CRESTS THE FLAT RIDGE OVER THE WEST AND PLUNGES INTO THE CENTRAL
U.S. A BACKDOOR COLD FRONT PUSHES FROM NORTH TO SOUTH THROUGH UTAH
ON MONDAY. THIS FRONTAL PASSAGE MARKS THE END OF THE EVENT AS A
MUCH COOLER AND DRIER AIRMASS SPREADS SOUTH THROUGH THE AREA.

FROM SUNDAY NIGHT THROUGH MONDAY EVENING THE WINDS ALOFT ARE VERY
STRONG. RIDGETOP GUSTS AT THE 11K ELEVATION COULD REACH 100 MPH
FROM SUNDAY NIGHT THROUGH MONDAY. THE COMBINATION OF THE VERY WET
DENSE SNOW AND THE HIGH WINDS IS GOING TO CREATE A HIGH AVALANCHE
HAZARD IN THE BACKCOUNTRY. COORDINATING WITH UAFC ON UPGRADING
THEIR AVALANCHE WATCH TO A WARNING THIS AFTERNOON.

PRETTY QUIET MONDAY NIGHT THROUGH EARLY WEDNESDAY. THE MODELS KEEP
GOING BACK AND FORTH ON THE DEPTH AND STRENGTH OF THE CHRISTMAS
STORM. THE KEY SEEMS TO BE HOW THEY HANDLE THE SPLITTING OF A
TROUGH NEAR 150W ON TUESDAY. THE EC KEEPS THE SOUTHERN PORTION OF
THE SPLIT NEAR OR WEST OF 150W WHILE THE GFS PUTS THE SOUTHERN
PORTION EAST OF 150W. THE REASON THIS IS IMPORTANT IS BECAUSE OF
THE LOCATION OF THE RIDGE THAT FORMS JUST DOWNSTREAM OF THIS
CLOSED LOW ON WEDNESDAY. WITH THE RIDGE FURTHER EAST IN THE
GFS...THE CHRISTMAS STORM TENDS TO BE SHUNTED FURTHER EAST WHILE
THE EC RIDGE POSITION ALLOWS THE STORM TO DIG MORE INTO THE GREAT
BASIN. TODAYS 12Z GFS/EC WERE PRETTY CLOSE WITH THE EC SLIGHTLY
COLDER/DEEPER. QUICK LOOK AT THE 18Z GFS SHOWS IT WANDERING BACK
TO THE WEAKER SOLUTION THAT WE SAW FROM THE 00Z AND 06Z GFS RUNS.
STAY TUNED.

BEYOND THURSDAY MODELS DIVERGE CONSIDERABLY ON DETAILS AND
FORECAST CONFIDENCE IS LOW.

&&

.AVIATION...CEILINGS AT THE SLC TERMINAL ARE EXPECTED TO REMAIN AT
OR BELOW 7000 FEET AGL THROUGH THE AFTERNOON AND EVENING. VFR
CONDITIONS AND ISOLATED LIGHT RAIN SHOWERS POSSIBLE AT TIMES
THROUGH THE PERIOD. THERE WILL BE A 50 PERCENT CHANCE OF MVFR
CONDITIONS DUE TO LOWERING CEILINGS IN HEAVIER RAIN SHOWERS AFTER
00Z. GENERALLY LIGHT SOUTHERLY SURFACE WINDS ARE
EXPECTED...ALTHOUGH ERRATIC WINDS ARE POSSIBLE IN SOME HEAVIER
SHOWERS.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM MST MONDAY
     FOR UTZ007>010-517.

WY...HIGH WIND WARNING FROM 5 AM SUNDAY TO 2 AM MST MONDAY FOR WYZ021.

&&

$$

PUBLIC...DUNN
AVIATION...YOUNG

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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