000
FXUS65 KFGZ 211624
AFDFGZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
930 AM MST TUE MAY 21 2013

.SYNOPSIS...
WESTERLY FLOW ALOFT WILL BRING BATCHES OF HIGH LEVEL CLOUDS ACROSS
ARIZONA TODAY. ON WEDNESDAY A LOW PRESSURE SYSTEM WILL MOVE INTO THE
PACIFIC NORTHWEST AND BECOME NEARLY STATIONARY. THIS LOW WILL
PRODUCE STRONGER WINDS ACROSS NORTHERN ARIZONA AND START A MULTIPLE
DAY CRITICAL FIRE WEATHER PATTERN WHICH WILL LAST INTO THE UPCOMING
WEEKEND. THE STRONGEST WINDS ARE CURRENTLY ANTICIPATED ON WEDNESDAY
AND THURSDAY.

&&

.DISCUSSION...
SHORT TERM FORECAST IN GOOD SHAPE WITH NO UPDATES.

&&

A WEAK HIGH PRESSURE RIDGE WILL MOVE THROUGH THE SOUTHWEST REGION
TODAY AS A LARGE LOW MOVES INTO THE PACIFIC NORTHWEST. DRY AND WARM
WEATHER CONDITIONS ARE FORECAST UNDER MOSTLY SUNNY SKIES. THE
PACIFIC NORTHWEST LOW WILL SETTLE IN OVER THE PACIFIC NORTHWEST
THROUGH THE WEEKEND...BRINGING AN EXTENDED PERIOD OF CRITICAL FIRE
WEATHER CONDITIONS WITH GUSTY WINDS AND LOW HUMIDITY LEVELS FROM
WEDNESDAY ONWARD.

MODELS ARE IN GOOD AGREEMENT THROUGH THURSDAY...INDICATING THE LOW
CENTER OVER WASHINGTON AND OREGON...WITH SHORTWAVES TRAVERSING THE
GREAT BASIN BOTH DAYS. WINDS ALOFT INCREASE ACROSS NORTHERN ARIZONA
AS THE SYSTEM APPROACHES...WITH PLENTY OF DRY AIR IN PLACE. THIS
SETS THE STAGE FOR CRITICAL FIRE WEATHER CONDITIONS AND A FIRE
WEATHER WATCH CONTINUES FOR WEDNESDAY THROUGH THURSDAY. SUSTAINED
SOUTHWEST WINDS OF 20-30 MPH WITH GUSTS NEAR 40 MPH ARE EXPECTED.
TEMPERATURES WILL REMAIN SEASONABLY WARM...NEAR AVERAGE FOR LATE MAY.

FRIDAY THROUGH EARLY NEXT WEEK...THE SAME GENERAL PATTERN
PERSISTS...THOUGH THE LOW OVER THE PAC NW SHOULD WEAKEN SLIGHTLY.
THERE IS A BIT MORE UNCERTAINTY REGARDING WIND SPEEDS IN ARIZONA
DURING THIS TIME PERIOD AS MODELS DIFFER IN THEIR HANDLING OF
ADDITIONAL SHORTWAVES MOVING TOWARD THE SOUTHWEST UNITED STATES. FOR
NOW...WE EXPECT A MINOR DECREASE IN WIND SPEEDS THROUGH THIS
PERIOD...BUT SPEEDS MAY STILL BE HIGH ENOUGH FOR CRITICAL FIRE
WEATHER CONDITIONS. THERE IS NO PRECIP IN SIGHT...WITH TEMPERATURES
RUNNING VERY NEAR SEASONAL AVERAGES.

&&

.AVIATION...FOR THE 18Z PACKAGE...VFR CONDITIONS EXPECTED OVER THE
NEXT 24 HRS. WINDS SW10-15G25KTS...DIMINISHING AFT 02Z. AVIATION
DISCUSSION NOT UPDATED FOR AMENDMENTS.

&&

.FIRE WEATHER...A WEAK RIDGE OF HIGH PRESSURE WILL MOVE ACROSS
ARIZONA TODAY WITH WARMER TEMPERATURES AND SOUTHWEST WINDS 10 TO 20
MPH.

WEDNESDAY AND THURSDAY...A STRONG TROUGH WILL DEVELOP ALONG THE WEST
COAST. SOUTHWEST WINDS WILL BECOME STRONG AND GUSTY AND WILL COMBINE
WITH VERY LOW RELATIVE HUMIDITY TO CREATE CRITICAL FIRE WEATHER
CONDITIONS ACROSS MUCH OF NORTHERN ARIZONA. A FIRE WEATHER WATCH IS
IN EFFECT FOR WEDNESDAY AND THURSDAY.

FRIDAY AND SATURDAY...A TROUGH WILL REMAIN OVER THE SOUTHWEST
BRINGING PERIODS OF STRONG AND GUSTY WINDS ALONG WITH VERY LOW
RELATIVE HUMIDITY. CRITICAL TO NEAR-CRITICAL FIRE WEATHER
CONDITIONS ARE EXPECTED TO CONTINUE.

EXTENDED FORECAST...STRONG WINDS AND LOW RELATIVE HUMIDITY WILL
CONTINUE THROUGH EARLY NEXT WEEK.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH WEDNESDAY AFTERNOON THROUGH THURSDAY EVENING FOR
FIRE WEATHER ZONES AZZ104>117-138>140.

&&
$$

PUBLIC.........41/ JJ
AVIATION.......DB
FIRE WEATHER...DB / MAS

FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT WEATHER.GOV/FLAGSTAFF