Hail in Arizona, July 15, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
920 AM MST SUN JUL 15 2007

.SYNOPSIS...HIGH PRESSURE ALOFT WILL REMAIN NEAR THE FOUR CORNERS.
ADEQUATE MOISTURE IN COMBINATION WITH DAYTIME HEATING WILL PROVIDE
ISOLATED TO SCATTERED THUNDERSTORMS MAINLY DURING THE AFTERNOON AND
EVENING HOURS. ACTIVITY WILL INCREASE FURTHER THROUGH THE UPCOMING
WEEK...AS STRONGER EASTERLY FLOW TAKES HOLD.

&&

.DISCUSSION...UPPER-MID HIGH CENTER IS CURRENTLY OVER NORTHEAST
ARIZONA-SOUTHWEST UTAH. EAST-NORTHEAST FLOW REGIME CONTINUES BELOW
HIGH FOR SOUTHEAST ARIZONA...WITH WEAK CIRCULATION CENTERS
PERIODICALLY EMBEDDED IN THE FLOW. UPPER LOW IS OFF THE BRITISH
COLUMBIA COAST WITH ASSOCIATED TROUGH SOUTH ALONG THE WEST COAST.
SOUTHERN STREAM DISTURBANCE IS SEVERAL HUNDRED MILES WEST OF THE
NORTHERN BAJA COAST. TROUGH WILL DEEPEN ALONG THE WEST COAST ON
MONDAY...AS HIGH SHIFTS SLIGHTLY EAST. FLOW BETWEEN THESE FEATURES
WILL CARRY SRN STREAM DISTURBANCE NORTH INTO SRN CALIFORNIA BY LATE
MONDAY AFTERNOON. UPPER TROUGH WILL DEEPEN FURTHER ALONG THE WEST
COAST THROUGH MID WEEK...BUT UPPER HIGH WILL REMAIN ANCHORED OVER
THE FOUR CORNERS. THIS WILL KEEP SOUTHEAST ARIZONA IN A FAVORABLE
EASTERLY FLOW PATTERN...WITH PROGRESSIVELY STRONGER WESTERLY MOVING
DISTURBANCES THROUGH THE PERIOD. IN FACT MODELS SHOW RATHER STRONG
EASTERLY WAVE APPROACHING THE AREA ON THURSDAY.

PLENTY OF DEBRIS CLOUDINESS REMAINS OVER THE AREA THIS MORNING FROM
OVERNIGHT THUNDERSTORM COMPLEX OVER GREENLEE AND GRAHAM COUNTIES.
THIS HAS SLOWED OUR WARMING BY A FEW DEGREES. MORNING TUS SOUNDING
INDICATES A SLIGHTLY MORE UNSTABLE TEMPERATURE PROFILE VERSUS
YESTERDAY...DUE TO ROUGHLY 2 DEGREES OF COOLING ABOVE 500 MB AND 2-3
DEGREES OF BOUNDARY LAYER WARMING...IN OTHER WORDS OUR LAPSE RATES
ARE STEEPER. MOISTURE IS A LITTLE BIT LOWER...MOSTLY DUE TO A
SLIGHTLY DRIER SURFACE ENVIRONMENT...YESTERDAYS DEWPOINTS WERE IN
THE LOWER 60S...TODAY WE HAVE UPPER 50S. STILL...PLENTY OF
MOISTURE ABOVE 700 MB AND 1.37 PW IS A RESPECTABLE MONSOON LEVEL
VALUE. DRIER AIR SHOWS UP ON GOES PW SAT OVER NORTHWEST CHIHUAHUA
AND MODELS SEEM TO HAVE INITIALIZED THIS WELL. SOME OF THIS DRYING
MAY FILTER INTO THE FAR SOUTHEAST THIS AFTERNOON. A SOMEWHAT
COMPLICATED THUNDERSTORM SCENARIO THIS AFTERNOON...CLOUD COVER WILL
LIKELY CAUSE ACTIVITY TO BE LATER STARTING. WE CERTAINLY HAVE A FEW
BOUNDARIES AND WEAK CIRCULATIONS LEFT OVER FROM OVERNIGHT
CONVECTION...BUT THEY ARE VERY HARD TO PICK OUT AT THIS TIME...WILL
HAVE TO WAIT FOR CLOUD COVER TO THIN A BIT MORE. OVERALL FEEL THAT
IF WE CAN GET ENOUGH SUN TO WARM TEMPS UP TO 100 DEGS SHOULD SEE AN
INCREASE IN ACTIVITY VERSUS THE PAST COUPLE OF DAYS.

MONDAY SHOULD SEE A FURTHER INCREASE IN ACTION...AS UPPER LEVEL
TEMPS COOL SOME MORE...AIDED BY SRN CALIFORNIA DISTURBANCE. MID AND
LATE WEEK LOOK VERY ACTIVE WITH PROGRESSIVELY STRONGER WESTERLY
MOVING DISTURBANCES AND PLENTY OF MOISTURE.

&&

.FIRE WEATHER...THE DAILY CYCLE OF MAINLY AFTERNOON AND EVENING
SHOWERS AND THUNDERSTORMS WILL OCCUR DURING THE UPCOMING WEEK. WINDS
WILL BE DIURNALLY DRIVEN...WITH AFTERNOON GUSTS UP TO 30 MPH DUE TO
STRONG SURFACE HEATING. ADDITIONALLY...ANY THUNDERSTORMS THAT DO
DEVELOP WILL BE CAPABLE OF PRODUCING STRONG GUSTY AND ERRATIC WINDS.
RELATIVE HUMIDITY VALUES OVERNIGHT WILL BE IN THE 45 TO 75 PERCENT
RANGE...WITH VALUES DROPPING IN THE AFTERNOON HOURS INTO THE 20 TO
30 PERCENT RANGE.

&&

.AVIATION...ISOLD TSRA/SHRA COVERAGE TODAY WITH BRIEF WIND GUSTS OF
30-40 KTS WITH THE STRONGEST TSTMS. AVIATION DISCUSSION NOT UPDATED
FOR TAF AND TWEB AMENDMENTS.

&&

.CLIMATE...THE CONSECUTIVE DAY STREAK OF HIGH TEMPERATURES OF 100 OR
GREATER AT THE TUCSON AIRPORT HAS REACHED 32 DAYS...WHICH IS THE 3RD
LONGEST ON RECORD. WE ARE CURRENTLY FORECASTING HIGH TEMPERATURES TO
BE 100 OR BETTER EACH DAY THROUGH JULY 21ST...WHICH WOULD TIE THE
ALL-TIME RECORD OF 39 CONSECUTIVE DAYS. HOWEVER...THE FORECAST IS
ALSO CALLING FOR AN INCREASE IN THUNDERSTORM ACTIVITY THIS WEEK
WHICH COULD PUT IN JEOPARDY ANY DAY AFTER MONDAY FOR HITTING 100
DEGREES. STAY TUNED. IN ANY EVENT...IT WILL BE ANOTHER HISTORIC RUN
OF 100+ TEMPERATURES FOR TUCSON.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...NONE.

&&

SHOEMAKER

WEATHER.GOV/TUCSON