FXUS65 KFGZ 061626
AFDFGZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
925 AM MST SUN DEC 6 2009
.SYNOPSIS...SCATTERED LIGHT RAIN AND SNOW SHOWERS WILL CONTINUE
THROUGH TONIGHT ALONG THE MOGOLLON RIM AND WHITE MOUNTAINS.
ELSEWHERE EXPECT INCREASING CLOUDS AND BREEZY WINDS. 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. A WINTER STORM WATCH IS IN EFFECT FOR MUCH OF
NORTHERN ARIZONA ABOVE 5000 FEET. AT LOWER ELEVATIONS SOUTH OF
THE RIM...EXPECT PERIODS OF MODERATE TO HEAVY RAIN. WEATHER
CONDITIONS SHOULD IMPROVE FROM NORTHWEST TO SOUTHEAST TUESDAY
AFTERNOON. UNSETTLED WEATHER SHOULD RETURN WEDNESDAY AFTERNOON.
&&
.DISCUSSION...
UPSLOPE STRATUS CLOUDS ARE OCCURRING ALONG THE MOGOLLON RIM AND
WHITE MTNS THIS MORNING. WE HAVE UPDATED TODAYS FORECAST TO INCREASE
CLOUD COVER AND THE CHANCE OF LIGHT SHOWERS ACROSS THE MOGOLLON RIM
AND ST JOHNS AREAS PER SATELLITE AND SFC OBSERVATIONS. THE PREVIOUS
DISCUSSION BELOW COVERS WELL THE UPCOMING STORM.
PREV DISCUSSION 400 AM....LITTLE CHANGE IN THE ONGOING FORECAST WITH
MAJOR STORM ON TRACK TO AFFECT THE AREA MONDAY INTO EARLY TUESDAY.
TODAY WILL SEE A FEW LATE DAY LIGHT SNOW SHOWERS ACROSS THE HIGHEST
TERRAIN... OTHERWISE FAIR WITH HIGH TEMPS IN THE UPPER 30S ACROSS
THE HIGHER ELEVATIONS AND MOGOLLON RIM...AND 40S ACROSS LOWER
ELEVATIONS.
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. THE BIG PICTURE DETAILS HAVE NOT CHANGED IN THE
PAST COUPLE DAYS. 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. IF THIS VERIFIES...BLIZZARD CONDITIONS
WILL OCCUR FOR A BRIEF TIME MONDAY NIGHT.
NO CHANGES TO CURRENT WINTER STORM WATCH. NEXT SHIFT WILL UPGRADE
THE WATCH TO A WARNING LATER TODAY.
DRYING WILL OCCUR LATE TUESDAY THROUGH WEDNESDAY BEHIND THE TROUGH.
THEN AN ACTIVE SUBTROPICAL JET WILL BRING ADDITIONAL MOISTURE AND
DISTURBANCES LATE IN THE WEEK WITH RAIN AND SNOW CHANCES RETURNING.
STAY TUNED FOR THE LATEST UPDATES CONCERNING THE UPCOMING WINTRY
WEATHER.
&&
.AVIATION...FOR THE 18Z PACKAGE...A STRONG STORM SYSTEM WILL
APPROACH ARIZONA OVER THE NEXT 24 HOURS. FOR THIS MORNING EXPECT
SCATTERED MVFR CONDITIONS IN THE HIGH COUNTRY WITH BKN-OVC CIGS 2-4
KFT AGL AND LIGHT SHOWER ACTIVITY. BY SUNDAY AFTERNOON SOUTHWEST
WINDS WILL INCREASE TO 15-25 KTS WITH GUSTS TO 30 KTS. TONIGHT
THROUGH MONDAY...CLOUD COVER WILL INCREASE OVERNIGHT AT ALL LEVELS
WITH AREAS OF BKN-OVC CIGS 2-4 KFT AGL...RAIN AND SNOW SHOWER
ACTIVITY WILL PICK UP SIGNIFICANTLY BY MONDAY MORNING WITH STRONG
SOUTHWEST WINDS CONTINUING. AVIATION DISCUSSION NOT UPDATED FOR
AMENDMENTS.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...WINTER STORM WATCH FROM MONDAY
MORNING THROUGH TUESDAY MORNING FOR ELEVATIONS ABOVE 5000 FEET FOR
AZ ZONES AZZ004>013-015-016-018-038>040.
WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY MORNING
ABOVE 5500 FEET FOR AZ ZONES AZZ014-017.
&&
$$
PUBLIC..................DL/PETRO
AVIATION/FIRE WEATHER...BOHLIN
VISIT WEATHER.GOV/FLAGSTAFF FOR NORTHERN ARIZONA WEATHER INFORMATION.
