FXUS65 KFGZ 070426
AFDFGZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
925 PM MST SUN DEC 6 2009
.SYNOPSIS...A MAJOR WINTER STORM WILL AFFECT NORTHERN ARIZONA MONDAY
INTO TUESDAY MORNING. SNOW LEVELS WILL RANGE FROM 5000 TO 6000
FEET...WITH HEAVY SNOW ACCUMULATIONS ABOVE 6000 FEET...ESPECIALLY
ALONG THE MOGOLLON RIM AND WHITE MOUNTAINS. AT LOWER ELEVATIONS
SOUTH OF THE RIM...EXPECT PERIODS OF MODERATE TO HEAVY RAIN. WEATHER
CONDITIONS SHOULD IMPROVE FROM NORTHWEST TO SOUTHEAST TUESDAY
AFTERNOON...WITH FAIR WEATHER THROUGH WEDNESDAY EVENING. UNSETTLED
WEATHER SHOULD RETURN THURSDAY THROUGH SATURDAY.
&&
.DISCUSSION...LIGHT UPSLOPE PRECIP HAS BEGUN (STARTING FROM THIS
AFTERNOON AND CONTINUING THROUGH THIS EVENING). 88D PICKING UP SOME
LIGHT RETURNS CONFINED VERY CLOSE TO THE UPSLOPE AREAS OVER THE
EASTERN MOGOLLON RIM AND WHITE MOUNTAINS. ONE REPORT OF AN INCH OF
SNOW THIS AFTERNOON CAME IN FROM MCNARY. STORM IS STILL ON
TRACK...SO NO SIGNIFICANT UPDATES TO THE FORECAST EXPECTED. THE MOST
INTENSE PERIOD OF HEAVY PRECIP. AND STRONGEST WINDS LOOK TO BEGIN
AROUND 3 TO 5 PM MONDAY AND CONTINUE THROUGH 4 TO 8 AM TUESDAY AND
THEN DECREASING FAIRLY RAPIDLY FROM THE NORTHWEST TO THE SOUTHEAST.
THE MOST CRITICAL WEATHER WILL BE OVERNIGHT MONDAY ABOVE 5500 FEET
WHERE 12 TO 25 INCHES OF SNOW IS EXPECTED WITH VERY WINDY
CONDITIONS... ZERO VISIBILITY DUE TO THE HEAVY SNOW...AND BLOWING
AND DRIFTING SNOW...ESPECIALLY FOR THE MOGOLLON RIM...INCLUDING
CITIES LIKE WILLIAM...FLAGSTAFF...DOWN THROUGH MUNDS PARK...MORMON
LAKE...HAPPY JACK...EAST OVER TO FOREST LAKES.
SHORT TERM CONCERNS...LOCALIZED STRONG WINDS ARE BEING REPORTED AND
ARE BEING OBSERVED IN DONEY PARK. CURRENT WIND READINGS ARE
INDICATING GUST FROM 50 TO 60 MPH. EXPECTING WINDS TO COME DOWN A
LITTLE TOWARD SUNRISE...HOWEVER EXPECTING WINDS TO PEAK AGAIN LATER
IN THE DAY ON MONDAY AND BECOME WIDE SPREAD. A SHORT TERM FORECAST
HAS BEEN ISSUED TO COVER THIS WIND EVENT...PRODUCT CAN BE FOUND
USING THE PRODUCT ID. PHXNOWFGZ UNDER THE TEXT PRODUCTS SECTION OF
OUR WEB PAGE ON THE LEFT HAND SIDE...OR CLICKING ON THE MAP FOR THE
DONEY PARK AREA.
&&
.PREVIOUS DISCUSSION /340 PM MST/...MODELS CONTINUE TO SHOW THAT A
VERY STRONG (SUPER SIZE) WINTER STORM WILL IMPACT NORTHERN ARIZONA
MONDAY THROUGH MID DAY TUESDAY. FEW CHANGES WERE MADE TO THE GRID
PACKAGE THROUGH NOON TUESDAY. WE HAVE UPGRADED THE WINTER STORM (WS)
WATCH TO A BLIZZARD WARNING FOR THE WESTERN AND EASTERN MOGOLLON RIM
FOR MONDAY INTO TUESDAY. MODELS MOVE A RAPIDLY DEEPENING SURFACE LOW
INTO THE NORTHLAND MONDAY EVENING AND GENERATE LOW LEVEL SW WINDS
INCREASING TO THE 35 TO 50 KT RANGE BY EARLY MONDAY EVENING ACROSS
THE WESTERN AND EASTERN MOGOLLON RIM. IT IS TO MUCH SFC WIND FOR TO
LONG TO COVER WITH A WINTER STORM WARNING. UPGRADED THE WS WATCH TO
WARNING FOR MUCH OF NRN AZ ABOVE 5000 FEET. WE WILL KEEP THE PAGE
ZONE AND LCR ZONES IN A WATCH AT THIS TIME AS GRIDDED SNOW LEVELS
AND SFC TEMPS ARE NOT QUITE IN SYNC TO GENERATE ACCUMULATING WARNING
CRITERIA SNOW AMOUNTS AT THIS TIME. THIS SYSTEM IS STILL
DEVELOPING...ALL ARE ENCOURAGE TO MONITOR FORTHCOMING FORECASTS.
CHECK THE PHXWSWFGZ FOR DETAILS.
THE DISCUSSION WRITTEN BY MR. PETRO EARLY SUNDAY MORNING COVERS THE
DETAILS OF THE WINTER STORM WELL AND IS BELOW.
MODELS CONTINUE TO BE IN GOOD AGREEMENT WITH THE TROUGH THAT IS
CURRENTLY CENTERED FROM OREGON TO IDAHO MOVING SOUTH AND EAST
THROUGH EARLY TUESDAY WHILE TEAMING UP WITH PACIFIC MOISTURE IN THE
SUBTROPICAL JET. STILL LOOKS LIKE PRECIP WILL BEGIN LATE SUNDAY
NIGHT AND INCREASE DURING THE DAY MONDAY WITH THE MOST INTENSE
PERIOD OF PRECIP OCCURRING A FEW HOURS AROUND 06Z TUESDAY. NOTED
THAT LOW LEVEL SOUTHWEST FLOW WILL INCREASE DURING THE DAY MONDAY
WITH A 50+ KT LOW LEVEL JET TUESDAY EVENING. UPSLOPE FLOW COMBINED
WITH ABUNDANT MOISTURE MOVING UP FROM THE SOUTHWEST WILL RESULT IN
PERIODS OF RAIN AND SNOW DURING THE DAY AHEAD OF THE MAIN SYNOPTIC
SCALE FORCING. THESE FEATURES WILL COMBINE WITH THE APPROACH AND
PASSAGE OF THE TROUGH AXIS EARLY TUESDAY MORNING TO MAXIMIZE LIFT.
FORECAST SOUNDINGS ALSO REVEAL LOW LEVEL WARMING AND MID LEVEL
COOLING BETWEEN 18Z MON AND 06Z TUESDAY. ALL THESE FEATURES WILL
COMBINE FOR SEVERAL HOURS OF INTENSE PRECIP BETWEEN 00Z-08Z TUESDAY.
GIVEN THE DESTABILIZING PROFILE INDICATED IN THE SOUNDINGS...A BRIEF
THUNDERSTORM CAN'T BE RULED OUT.
AS FOR SNOW LEVELS...NOT MUCH CHANGE...STILL EXPECTING SNOW LEVELS
WILL START OFF AT 5500-6500 FT...WHICH WILL LOWER A COUPLE HUNDRED
FEET DURING THE INTENSE PRECIP AND FURTHER LOWER AFTER TROUGH
PASSAGE. WITH ELEVATIONS ABOVE 6500 REMAINING ALL SNOW...1-2 FEET OF
SNOWFALL STILL LOOKS ON TRACK. LIGHTER AMOUNTS EXPECTED BETWEEN
5000-6500 FEET. BELOW THE SNOW LEVEL AND MAINLY SOUTH AND SOUTHWEST
OF THE MOGOLLON RIM...SEVERAL INCHES OF RAINFALL ARE EXPECTED. IF
THUNDERSTORMS DO INDEED DEVELOP ACROSS OUR SOUTHERN MOST
ZONES...WILL HAVE TO CLOSELY MONITOR FOR FLASH FLOOD POTENTIAL GIVEN
THE HEAVY QPF AMOUNTS THAT ARE EXPECTED.
FINALLY...GUIDANCE STILL INDICATES INCREASING SOUTHWEST WINDS DURING
THE DAY MONDAY BECOMING SUSTAINED AT 25 TO 35 MPH WITH GUSTS TO
40-55 MPH BY LATE IN THE DAY. THIS WILL RESULT IN BLOWING AND
DRIFTING SNOW AND VERY HAZARDOUS TRAVEL CONDITIONS. NOTED THAT MAV
GUIDANCE SHOWS SEVERAL HOURS OF 35+ KT SUSTAINED WINDS MONDAY NIGHT
ACROSS THE HIGHER TERRAIN. PETRO.
FROM MID DAY TUESDAY THROUGH EARLY THURSDAY MORNING...CLEARING
WEATHER SHOULD MOVE INTO THE NORTHLAND FROM NORTHWEST TO SOUTHEAST
TUESDAY AFTERNOON. CROSS SECTION INDICATE WEST TO NORTHWEST FLOW
ALOFT MAY KEEP SOME STRATUS ALONG THE UPSLOPE SIDES OF OUR HIGHER
TERRAIN...BUT DRY WEATHER IS FORECAST.
THURSDAY THROUGH SUNDAY...MOIST WESTERLY FLOW FROM OFF THE PACIFIC
WILL PERSIST. MODELS BRING A WEAK LOW ACROSS THE NORTHLAND
IN THE THURSDAY NIGHT FRIDAY TIME FRAME. THUS ANOTHER CHANCE OF
PRECIPITATION IS OUR FORECAST.
&&
.AVIATION...FOR THE 06Z PACKAGE...A STRONG WINTER STORM WILL MOVE
INTO NORTHERN ARIZONA OVER THE NEXT 24 HOURS. TONIGHT THROUGH MONDAY
MORNING...EXPECT MVFR/LOCAL IFR CIGS OVER HIGHER TERRAIN AND LOCAL
MVFR OVER LOWER ELEVATIONS. RAIN AND SNOW SHOWER ACTIVITY WILL
INCREASE IN COVERAGE BY AROUND 12Z. CONDITIONS WILL STEADILY
DETERIORATE FROM MID-MORNING MONDAY INTO MONDAY NIGHT. ABOVE 5000
FEET...EXPECT WIDESPREAD SNOW WITH IFR AND LOCAL MVFR CONDITIONS.
THE LOWER ELEVATIONS WILL SEE MAINLY MVFR/LOCAL IFR CONDITIONS IN
RAIN. STRONG SOUTHWEST WINDS ARE ALSO FORECAST...WITH SUSTAINED
WINDS OF 20-30KT G30-40KT...INCREASING TO 25-35KT G35-45KT AFTER
00Z/TUE. THE WINDS WILL CREATE AREAS OF BLOWING SNOW WITH VISIBILITY
NEAR ZERO AT TIMES. AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...
...BLIZZARD WARNING IN EFFECT FROM 8 AM MONDAY TO NOON MST TUESDAY
AZZ015-016...
...WINTER STORM WARNING IN EFFECT FROM 8 AM MONDAY TO NOON MST
TUESDAY FOR AREAS ABOVE 5000 AZZ004-006>011-018-038...
..WINTER STORM WARNING IN EFFECT FROM 5 PM MONDAY TO NOON MST
TUESDAY AZZ017...
...WINTER STORM WATCH NOW IN EFFECT FROM MONDAY AFTERNOON THROUGH
TUESDAY MORNING FOR AREAS ABOVE 5000 FEET AZZ005-012>14...
&&
$$
PUBLIC..................TOM/DL/PETRO
AVIATION/FIRE WEATHER...JJ
VISIT WEATHER.GOV/FLAGSTAFF FOR NORTHERN ARIZONA WEATHER INFORMATION.
