Severe Thunderstorm Warning 1, NWS Flagstaff, AZ

AREA FORECAST DISCUSSION...RETRANSMISSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
230 PM MST SUN FEB 11 2007

.SYNOPSIS...EXPECT A SERIES OF PACIFIC STORM SYSTEMS TO AFFECT OUR
REGION THROUGH MID-WEEK. RAIN AND HIGH ELEVATION SNOW SHOWERS WILL
CONTINUE TONIGHT. AFTER A BRIEF BREAK MONDAY...RAIN AND SNOW
SHOWERS WILL RETURN AS A COLDER SYSTEM MOVES IN FOR TUESDAY AND
WEDNESDAY. HIGH PRESSURE WILL RE-BUILD LATER IN THE WEEK WITH A
WARMING TREND...AND DRIER CONDITIONS.

&&

.DISCUSSION...A COLD FRONT AND UPPER LEVEL WX SYSTEM IS RESPONSIBLE
FOR THE LINE SHOWERS AND ISOLATED THUNDERSTORMS ALONG AND EAST OF A
LINE EXTENDING FROM NAVAJO NATIONAL MONUMENT DOWN THROUGH FLAGSTAFF.
THE MAIN LIFT PRODUCED BY THIS STORM SYSTEM WILL AFFECT THE CENTRAL
AND EASTERN HALF OF THE FORECAST AREA THIS EVENING WITH THE SYSTEM
SHIFTING EAST INTO NEW MEXICO BETWEEN MIDNIGHT AND 5 AM WITH SHOWERS
DIMINISHING ACROSS THE AREA BY MONDAY MORNING. SNOW LEVELS ARE
FORECAST TO DROP TO AROUND THE 6000 TO 6500 FOOT LEVEL BY MONDAY
MORNING WITH SOME SNOW ACCUMULATION ABOVE THAT ELEVATION...AMOUNTS
FROM TRACE UP TO 2 INCHES OF SNOW ARE POSSIBLE WITH 4-5 INCHES ABOVE
8500-9000 FEET...MAINLY FROM THE CHUSKA MOUNTAINS AND NORTHEAST
PLATEAUS AND OVER THE MOGOLLON RIM AND WHITE MOUNTAINS STRETCHING
FROM FLAGSTAFF SOUTHEAST THROUGH HEBER AND ALPINE.

ANOTHER DEEPER AND COLDER SYSTEM IS FORECAST TO MOVE IN ALONG THE
WEST COAST LATE MONDAY AND THEN MOVE ACROSS THE AREA TUESDAY AND
THEN MOVING EAST OF THE AREA TUESDAY NIGHT. SNOW LEVELS ARE FORECAST
TO DROP TO AROUND 5000 FEET. THIS SYSTEM HAS WEAK OROGRAPHIC AND
SYNOPTIC SCALE FORCING TO WORK ON THE ATMOSPHERE. HOWEVER THE ATMOS
WILL BE COLD ENOUGH FOR FAIRLY STEEP LAPSE RATES AND GOOD ICE MICRO
PHYSICS. FOR THIS REASON THIS SYSTEM HAS THE POTENTIAL TO PRODUCE
SEVERAL INCHES OF SNOW ABOVE 5500 FEET...MAINLY ALONG THE MOGOLLON
RIM...WHITE MOUNTAINS AND PORTIONS OF THE NORTHEAST PLATEAUS AND
CHUSKA MOUNTAINS. GIVEN THE INSTABILITY AND WEAK FLOW WITH THIS
SYSTEM THERE IS THE POSSIBILITY THAT HEAVIER SHOWERS COULD FORM AND
PERSISTENTLY MOVE OVER SOME FAVORED UPSLOPE AREAS THUS PRODUCING
HIGHER SNOWFALL AMOUNTS. WE WILL BE WATCHING THIS SYSTEM FOR A
POSSIBLE SNOW ADVISORY FOR TUESDAY INTO TUESDAY EVENING.
ANOTHER WEAK UPPER LEVEL WX DISTURBANCE WILL MOVE RAPIDLY
SOUTH-SOUTHEAST ACROSS THE AREA WEDNESDAY...THUS PROLONG PRECIP
ACROSS NORTHERN PORTIONS OF ARIZONA WITH THE STRONGER FORCING OVER
EASTERN SECTIONS OF THE FORECAST AREA FROM THE CHUSKA MOUNTAINS AND
NORTHEAST PLATEAUS SOUTH INTO THE EASTERN MOGOLLON RIM AND WHITE
MOUNTAINS FROM HEBER TO SHOW LOW TO ALPINE.

A STRONG RIDGE OF HIGH PRESSURE IS FORECAST TO BUILD IN OVER THE
AREA THURSDAY INTO SATURDAY WITH DRY CONDITIONS AND HIGH
TEMPERATURES WARMING WELL ABOVE THE SEASONAL AVERAGES. ANOTHER STORM
SYSTEM IS SHAPING UP FOR LATER IN THE WEEK...HOWEVER DIFFERENCES IN
MODEL RUNS STILL LEAVE A GOOD AMOUNT OF UNCERTAINTY TO DEAL WITH.
FOR NOW WE COVERED THE LATE SATURDAY INTO SUNDAY TIME PERIOD WITH
SLIGHT CHANCE OF PRECIP.

.AVIATION...FOR THE 00Z PACKAGE...CLOUD DECKS AROUND 13 KFT MSL WILL
CONTINUE THIS EVENING...WITH CEILINGS AROUND 2 KFT AGL IN SHOWERS
OVER SOME OF THE HIGHER ELEVATION AREAS. SNOW LEVELS WILL AROUND 8
KFT MSL THIS EVENING WILL LOWER TO AROUND 6-7 KFT MSL AFTER 05Z
MONDAY. SHOWERS ACTIVITY WILL END FROM WEST TO EAST BEGINNING WEST
OF
TWEB ROUTE 390 BY 02Z. AVIATION DISCUSSION NOT UPDATED FOR
AMENDMENTS.
&&

.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.

&&

TC/MS