AFDFGZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
245 AM MST FRI SEP 17 2004
.SYNOPSIS...AFTER ANOTHER SUNNY AND DRY DAY TODAY...CONDITIONS WILL
CHANGE RAPIDLY ACROSS THE REGION OVER THE WEEKEND. DEEP MOISTURE
FROM SOUTH OF THE STATE WILL ARRIVE BY SATURDAY...AND PERSIST WELL
INTO MONDAY. THIS MOISTURE WILL LEAD TO WIDESPREAD SHOWERS AND
THUNDERSTORMS ACROSS MUCH OF THE AREA ALL WEEKEND...AND INTO EARLY
MONDAY. IN ADDITION TO THE RAIN...BREEZY TO LOCALLY WINDY CONDITIONS
ARE EXPECTED ACROSS THE REGION AS A COLD FRONT APPROACHES FROM THE
WEST. THIS FRONT WILL END THE RAINFALL MONDAY AFTERNOON OR EVENING
AND USHER COLDER TEMPERATURES INTO MUCH OF THE STATE THROUGH THE
MIDDLE PART OF NEXT WEEK.
&&
.DISCUSSION...COMPLICATED PATTERN FOR THE NEXT 4 DAYS OR SO AS
HURRICANE JAVIER WILL BEGIN TO INFLUENCE OUR WEATHER. SLOWER AND
FURTHER WEST FORECAST OF A COLD PACIFIC NORTHWEST TROUGH OVER THE
WEEKEND WILL ALLOW JAVIER AND MOST IMPORTANTLY...ALL THE MOISTURE
AROUND JAVIER...TO MOVE BODILY NORTHWARD INTO THE SOUTHWEST. HIGHER
PW AIR AHEAD OF JAVIER EXPECTED TO MAKE IT INTO ARIZONA AS EARLY AS
TONIGHT...WITH DEEPER MOISTURE ARRIVING BY EARLY SATURDAY. AT THE
SAME TIME...THE TROUGH THAT ENTERS THE PACIFIC NORTHWEST DROPS SOUTH
INTO THE WESTERN GREAT BASIN...THUS STRENGTHENING THE SOUTHERLY
GRADIENTS OVER ARIZONA AT ALL LEVELS.
GRADIENTS ARE ENOUGH FOR WIND ADVISORIES IN A CLEAR AND WELL MIXED
ATMOSPHERE...BUT THIS WILL NOT BE THE CASE OVER THE WEEKEND.
ALTHOUGH WE WILL BE BREEZY TO LOCALLY WINDY AT TIMES...ALL THE
PRECIP AND CLOUD COVER SHOULD KEEP THINGS FROM REACHING ADVISORY
CRITERIA.
WE WILL BE IN THE ENTRANCE REGION OF A 90 KNOT JET BY SATURDAY
AFTERNOON...WITH MODERATE DIV ALOFT CONTINUING INTO SUNDAY. AIRMASS
NOT TERRIBLY UNSTABLE...BUT LIFTED INDICES ARE AROUND ZERO...WITH A
DEEP SATURATED LAYER AND STRONG UPSLOPE FLOW...WE SHOULD WRING OUT
PLENTY OF MOISTURE.
BY SUNDAY AND EARLY MONDAY...THE AIRMASS BECOMES MORE BAROCLINIC AS
THE TROUGH AXIS APPROACHES. THIS WILL INTENSIFY RAIN AND POSSIBLY
LEAD TO SEVERE WEATHER BEFORE THE WHOLE MESS SWEEPS OUT TO THE EAST
MONDAY AFTERNOON. THE COLD FRONT ASSOCIATED WITH THE TROUGH AXIS
MONDAY AFTERNOON WILL BE QUITE NOTICEABLE...WITH 700 MB TEMPERATURES
FALLING AROUND 10 DEGREES. THIS COOL AIRMASS WILL REMAIN IN PLACE
FOR THE FIRST AND MIDDLE PART OF NEXT WEEK...AND THE AIRMASS WILL
DRY OUT AND STABILIZE CONSIDERABLY. SOME TEMPERATURE RECOVERY WILL
OCCUR BY DAYS SIX OR SEVEN...BUT WILL STAY DRY. PETERSON.
Dennis
We'll just have to wait and see!
