Severe Thunderstorm Warning 1, NWS Flagstaff, AZ

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
600 PM MST WED FEB 20 2008

.SYNOPSIS...RAIN AND SNOW SHOWERS...AND A FEW THUNDERSTORMS...WILL
MOVE ACROSS NORTHERN ARIZONA THIS EVENING AND OVERNIGHT. SNOW LEVELS
WILL FALL FROM AROUND 7000 FEET THIS EVENING TO AROUND 6000 FEET BY
THURSDAY MORNING. TEMPERATURES WILL REMAIN BELOW NORMAL FOR THE NEXT
SEVERAL DAYS.

&&

.DISCUSSION...THE LATEST SATELLITE IMAGERY SHOWS THE CENTER OF THE
LOW MOVING INTO NORTHERN ARIZONA WITH DOPPLER RADAR SHOWING SEVERAL
BANDS OF MODERATE PRECIPITATION MOVING INTO WESTERN YAVAPAI AND
COCONINO COUNTIES. EXPECT CONTINUED BANDS OF SNOW AND RAIN TO
DEVELOP OVERNIGHT WITH SEVERAL INCHES OF SNOWFALL POSSIBLE ABOVE
6000 FEET. BY THURSDAY AFTERNOON THIS SYSTEM WILL BE EAST OF ARIZONA
AND WEATHER CONDITIONS ARE EXPECTED TO IMPROVE FROM WEST TO EAST.

ON FRIDAY AND SATURDAY...A SECOND LOW PRESSURE SYSTEM IS EXPECTED TO
PRODUCE GOOD CHANCES FOR MORE SNOW AND RAIN ACROSS MUCH OF THE
NORTHLAND. BOTH THE GFS AND EUROPEAN MODELS SHOW A BROAD TROUGH OF
LOW PRESSURE WITH A COLD FRONT MOVING INTO THE STATE FRIDAY
AFTERNOON. THIS NEXT SYSTEM HAS FAIRLY WEAK AND ELEVATED
DYNAMICS...HOWEVER THE OROGRAPHIC FORCING APPEARS TO BE BETTER THAN
THE LAST SYSTEM. THIS MEANS THE HIGHER TERRAIN AREAS WILL PROBABLY
SEE ENHANCED AMOUNTS OF PRECIPITATION AS COMPARED TO THE VALLEY
REGIONS. MODEL RUN TO RUN GUIDANCE ON THIS SYSTEM IS IMPROVING AND
CONFIDENCE IS FAIR FOR A WIDESPREAD EVENT WITH LOW AMOUNTS OF
MEASURABLE PRECIPITATION. BY SATURDAY MORNING WEATHER CONDITIONS
SHOULD IMPROVE FROM WEST TO EAST AS THE LOW MOVES AWAY FROM ARIZONA.

SUNDAY AND MONDAY...A THIRD SYSTEM IS FORECAST TO AFFECT NORTHERN
ARIZONA ON SUNDAY EVENING INTO MONDAY MORNING. THE CENTER OF THIS
STORM IS FORECAST TO TRACK THROUGH SOUTHERN IDAHO AND WYOMING
KEEPING THE BEST DYNAMICS AND MOISTURE NORTH OF THE STATE. UNLESS
THE FORECAST TRACK MOVES THIS SYSTEM FURTHER SOUTH WE WILL PROBABLY
SEE LIMITED AMOUNTS OF PRECIPITATION. MODEL INCONSISTENCIES FROM RUN
TO RUN HAVE CONTINUED TO KEEP FORECAST CONFIDENCE LOW ON THIS THIRD
SYSTEM. THEREFORE WE ARE KEEPING CHANCES FOR PRECIPITATION LOW UNTIL
THE FORECAST GUIDANCE IMPROVES. CHANGES TO THE FORECAST TRACK ARE
VERY POSSIBLE WITH THIS SYSTEM AND THESE CHANGES WILL DIRECTLY
AFFECT THE LOCATION AND AMOUNTS OF PRECIPITATION. STAY TUNED FOR
UPDATES AS THIS SYSTEM GETS CLOSER.

&&

.AVIATION....AVIATION...FOR THE 00Z PACKAGE...A COLD FRONT WILL MOVE
FROM WEST TO EAST ACROSS NORTHERN ARIZONA OVERNIGHT BRINGING AN
INCREASING CHANCE OF RAIN AND SNOW SHOWERS. THE SNOW LEVEL WILL BE
AROUND 5500 TO 6000 FEET OVERNIGHT. IN ADDITION...EXPECT WIDESPREAD
MVFR CONDITIONS WITH LOCAL IFR CONDITIONS OVER THE MOUNTAINS. ON
THURSDAY SHOWERS WILL BE ON THE DECREASE WITH WIDESPREAD CEILINGS OF
2000-4000 FEET OVER THE MOUNTAINS. CONDITIONS CONTINUING AVIATION
DISCUSSION NOT UPDATED FOR AMENDMENTS.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...SNOW ADVISORY IN EFFECT UNTIL 5
AM MST THURSDAY ABOVE 7000 FEET FOR AZZ004.

&&

DB/BOHLIN/MCCOLLUM

HAZARDOUS WEATHER OUTLOOK...CORRECTION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
228 PM MST WED FEB 20 2008

AZZ004>018-037>040-210700-
KAIBAB PLATEAU-MARBLE AND GLEN CANYONS-GRAND CANYON COUNTRY-
COCONINO PLATEAU-YAVAPAI COUNTY MOUNTAINS-
NORTHEAST PLATEAUS AND MESAS HWY 264 NORTHWARD-CHINLE VALLEY-
CHUSKA MOUNTAINS AND DEFIANCE PLATEAU-
LITTLE COLORADO RIVER VALLEY IN COCONINO COUNTY-
LITTLE COLORADO RIVER VALLEY IN NAVAJO COUNTY-
LITTLE COLORADO RIVER VALLEY IN APACHE COUNTY-
WESTERN MOGOLLON RIM-EASTERN MOGOLLON RIM-WHITE MOUNTAINS-
NORTHERN GILA COUNTY-YAVAPAI COUNTY VALLEYS AND BASINS-
OAK CREEK AND SYCAMORE CANYONS-BLACK MESA AREA-
NORTHEAST PLATEAUS AND MESAS SOUTH OF HWY 264-
228 PM MST WED FEB 20 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST CENTRAL
ARIZONA...NORTH CENTRAL ARIZONA...NORTHEAST ARIZONA AND WEST
CENTRAL ARIZONA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A SNOW ADVISORY REMAIN IN EFFECT FOR THE KAIBAB PLATEAU FROM
THIS AFTERNOON UNTIL THURSDAY MORNING FOR ELEVATIONS ABOVE
7000 FEET.

A SERIES OF PACIFIC STORM SYSTEMS WILL AFFECT NORTHERN ARIZONA FOR
THE NEXT 3 DAYS. THE FIRST STORM HAS THE POTENTIAL TO PRODUCE 2 TO 4
INCHES OF SNOWFALL OVERNIGHT ABOVE 6500 FEET WITH LOCALLY HIGHER
AMOUNTS IN THE STRONGEST SNOW BANDS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

ANOTHER STORM SYSTEM IS EXPECTED TO ARRIVE ON FRIDAY. THE LOW
CENTER AND BEST DYNAMICS WITH THIS STORM ARE FORECAST TO BE NORTH
OF THE STATE. THE CURRENT FORECAST CALLS FOR AROUND 1 TO 3 INCHES
OF SNOWFALL ABOVE 6500 FEET WITH LOCALLY HIGHER AMOUNTS IN SOME
FAVORED HIGH TERRAIN AREAS.

.SPOTTER INFORMATION STATEMENT...

RB