Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 212123
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
223 PM MST THU MAY 21 2015

.SYNOPSIS...A SERIES OF LOW PRESSURE SYSTEMS MOVING NORTH OF THE
AREA WILL BRING GUSTY WINDS AND COOLER TEMPERATURES INTO SATURDAY.
WE SHOULD THEN SEE A WARMING TREND WITH TEMPERATURES RECOVERING TO
NORMAL VALUES ALONG WITH LESS WIND MOST OF NEXT WEEK.

&&

.DISCUSSION...WATER VAPOR IMAGERY AND 21/12Z UPPER-AIR PLOTS SHOW A
LOW PRESSURE SYSTEM JUST OFF THE NORTH CENTRAL CALIFORNIA COAST...
WITH RIDGING ACROSS TEXAS...NEW MEXICO AND INTO THE CENTRAL ROCKIES.

IR AND VISIBLE SATELLITE IMAGERY SHOWS THE EXTENSIVE CLOUDINESS THAT
COVERED MUCH OF THE SOUTHWEST U.S. HAS SHIFTED NORTH AND
EAST...ESPECIALLY INTO WESTERN NEW MEXICO...WITH SOME THUNDERSTORM
ACTIVITY SEEN JUST ACROSS THE NEW MEXICO BORDER.

THIS MORNINGS KTWC SOUNDING REVEALED A PRECIPITABLE WATER VALUE OF
0.37 WHICH IS FAIRLY SIMILAR FROM THE PAST SEVERAL SOUNDINGS. THE
WINDS IN THE PROFILE REFLECT THE EXPECTED INCREASE IN WINDS WITH
FAIRLY LIGHT WINDS RIGHT OFF THE DECK...WITH 13 KNOTS AT 850MB...
NEARLY 30 KN0TS AT 700MB AND 50+ KNOTS JUST ABOVE 500MB. CURRENTLY
ACROSS SOUTHEAST ARIZONA WINDS RANGE FROM AROUND 15 TO 25 MPH WITH
GUSTS OF AROUND 25 TO 30 MPH. MANY LOCATIONS ALONG THE INTERNATIONAL
BORDER AND NEAR TUCSON HAVE MET THE MINIMUM RH CRITERIA FOR RED FLAG
CONDITIONS...BUT THE WINDS HAVE ONLY BRIEFLY BEEN MET IN A FEW
LOCATIONS (SEE FIRE WEATHER SECTION BELOW FOR ADDITIONAL DETAILS
ABOUT FIRE WEATHER CONCERNS FOR THE REMAINDER OF TODAY AND FRIDAY).

THE LOW PRESSURE SYSTEM ALONG THE CALIFORNIA COAST WILL CONTINUE TO
MOVE EAST THROUGH THE EARLY PART OF THE WEEKEND...BUT THE BULK OF
THE MOISTURE ASSOCIATED WITH THIS SYSTEM WILL REMAIN WELL TO THE
NORTH AND/OR EAST OF ARIZONA SO ONLY EXPECTING ISOLATED MOUNTAIN
SHOWERS/THUNDERSTORMS THIS AFTERNOON AND AGAIN THIS WEEKEND...MAINLY
FOR THE WHITE MOUNTAINS.

ONCE THIS SYSTEM EXITS TO THE EAST LATE THIS WEEKEND...WE WILL SEE
SEVERAL DISTURBANCES MOVING BY MAINLY TO THE NORTH WITH LITTLE
THREAT FOR PRECIPITATION. THESE DISTURBANCES SHOULD KEEP HIGH
PRESSURE TO OUR SOUTH THROUGH NEXT WEEK. PREVIOUS MODEL
RUNS...ESPECIALLY THE ECMWF...WERE TRYING TO DEPICT THE HIGH
PRESSURE TO OUR SOUTH BUILDING NORTHWARD...BUT LATEST EURO HAS IT
WELL TO THE SOUTH OR SOUTHWEST...WEST OF BAJA THROUGH LATE NEXT
WEEK.

FOR TUCSON...HIGH TEMPS WILL BE BELOW NORMAL THROUGH THE ENTIRE
FORECAST PERIOD. HOWEVER...HIGHS WILL RUN 10 TO 15 DEGS BELOW NORMAL
FRIDAY AND SATURDAY...THEN 5 TO 10 DEGS BELOW NORMAL SUNDAY AND
MONDAY AND AROUND 2 TO 4 DEGS BELOW NORMAL TUESDAY THROUGH THURSDAY.
LOW TEMPERATURES GENERALLY 5 TO 8 DEGS BELOW NORMAL FRIDAY THROUGH
SUNDAY MORNINGS...THEN 2 TO 4 DEGS BELOW NORMAL MONDAY AND TUESDAY
AND NEAR TO SLIGHTLY BELOW NORMAL WEDNESDAY AND THURSDAY.

&&

.AVIATION...VALID THRU 23/00Z. FEW-SCT CLOUDS AT 10-15K FT AGL AND
SCT-BKN CLOUDS ABOVE 20K FT THRU 22/04Z. AFT 22/04Z...FEW-SCT CLOUDS
AT 20K FT AGL. SLY/SWLY SURFACE WIND AT 12-25 KTS WITH GUSTS OF 25-
35 KTS THRU 22/03Z...WITH THE STRONGEST SURFACE WIND EAST OF KTUS IN
THE VICINITY OF KALK...KFHU AND KDUG. SURFACE WIND DIMINISHING AFTER
22/03Z. SURFACE WIND GENERALLY LESS THAN 10 KTS BETWEEN 22/06Z AND
22/13Z. INCREASING SWLY SURFACE WIND AFT 22/13Z...WITH SWLY SURFACE
WIND AT 15-25 KTS AND GUSTS TO 25-35 KTS AFT 22/17Z. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...A COOLING TREND IS EXPECTED THROUGH SATURDAY BEFORE
TEMPERATURES WARM TO NEAR-NORMAL LEVELS NEXT WEEK ALONG WITH DRY
CONDITIONS. THE MAIN CONCERN CONTINUES TO BE THE STRONG SOUTH TO
SOUTHWEST WINDS THROUGH FRIDAY. CRITICAL FIRE WEATHER CONDITIONS MAY
BE MET IN A FEW LOCATIONS THIS AFTERNOON/EVENING AND AGAIN FRIDAY
AFTERNOON...PRIMARILY ACROSS SOUTHERN PORTIONS OF FIRE WEATHER ZONES
151 AND 152. HOWEVER...IF CRITICAL THRESHOLDS ARE MET...THEY ARE
EXPECTED ONLY FOR BRIEF PERIODS AND OVER RELATIVELY LOCALIZED AREAS.
WE WILL CONTINUE TO KEEP A CLOSE EYE OUT FOR THE POTENTIAL FOR ANY
WATCHES AND/OR WARNINGS.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...NONE

&&

$$

PUBLIC...MOLLERE
AVIATION/FIRE WEATHER...ZELL

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