Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 220908
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
208 AM MST TUE APR 22 2014

.SYNOPSIS...BREEZY TO LOCALLY WINDY CONDITIONS ARE EXPECTED TODAY
AND ESPECIALLY WEDNESDAY AS A SYSTEM BRUSHES BY NORTH OF THE AREA.
LESS WIND THURSDAY AND FRIDAY BEFORE A STRONGER SYSTEM BRINGS WINDY
CONDITIONS THIS WEEKEND...ALONG WITH A FEW MOUNTAIN SHOWERS MAINLY
NORTHEAST OF TUCSON.

&&

.DISCUSSION...WATER VAPOR IMAGERY AND 22/00Z UPPER-AIR PLOTS SHOW
THE RIDGE AXIS THAT BROUGHT WARM TEMPERATURES TO THE REGION
YESTERDAY CONTINUES TO PUSH EASTWARD AND IS CURRENTLY OVER NEW
MEXICO. MEANWHILE...AN APPROACHING TROUGH OF LOW PRESSURE IS
CURRENTLY MAKING ITS WAY TOWARD THE CALIFORNIA COAST. IR SATELLITE
IMAGERY SHOWS MOSTLY CLEAR SKIES FOR SOUTHEAST ARIZONA...BUT
EXTENSIVE CLOUDINESS AHEAD OF THE AFOREMENTIONED TROUGH RESIDES
ACROSS MUCH OF NEVADA AND UTAH...BUT ALSO PORTIONS OF CALIFORNIA AND
NORTHERN ARIZONA AND NEW MEXICO AS WELL.

MODELS INDICATE THAT THE TROUGH IS EXPECTED TO MOVE ONSHORE INTO
NORTHERN CALIFORNIA THIS MORNING...THEN INTO THE GREAT BASIN THIS
AFTERNOON. AS THIS OCCURS THE PRESSURE GRADIENT BETWEEN THE EXITING
HIGH PRESSURE TO OUR EAST AND THE APPROACHING LOW PRESSURE TO OUR
NORTHWEST WILL RESULT IN AN INCREASE IN THE WINDS TO THE BREEZY
CATEGORY. BY WEDNESDAY THE TAIL END OF THIS SYSTEM WILL BRUSH
THROUGH MAINLY NORTHERN AND CENTRAL ARIZONA RESULTING IN A
CONTINUATION OF BREEZY TO LOCALLY WINDY CONDITIONS...BUT WITH THE
STRONGEST WINDS ON WEDNESDAY OCCURRING BETWEEN TUCSON AND THE NEW
MEXICO BORDER. SEE THE FIRE WEATHER SECTION BELOW FOR DETAILS
REGARDING IMPACTS THIS SYSTEM WILL HAVE ON FIRE WEATHER CONCERNS
TODAY AND WEDNESDAY. THIS SYSTEM WILL ALSO RESULT IN A DECREASE IN
HIGH TEMPERATURES BY SEVERAL DEGREES COMPARED TO THE EXPECTED HIGHS
FOR THIS AFTERNOON.

MODELS IN GENERAL AGREEMENT THAT THIS SYSTEM WILL EXIT TO THE EAST
WEDNESDAY EVENING WITH ZONAL FLOW DEVELOPING BEHIND THIS SYSTEM
THURSDAY INTO EARLY FRIDAY BEFORE ANOTHER PACIFIC SYSTEM BEGINS TO
IMPACT NORTHERN AND CENTRAL CALIFORNIA ON FRIDAY. BY LATE FRIDAY OR
EARLY SATURDAY THE MODELS SHOW THIS SYSTEM MOVING INTO WESTERN OR
NORTHWESTERN ARIZONA. THIS SYSTEM WILL HAVE ENOUGH MOISTURE
ASSOCIATED WITH IT TO JUSTIFY AT LEAST SLIGHT CHANCE POPS MAINLY FOR
THE WHITE MOUNTAINS OF GRAHAM AND GREENLEE COUNTIES FOR SATURDAY AND
SATURDAY NIGHT. THE SYSTEM WILL ALSO BRING EVEN STRONGER WINDS TO
THE AREA THAN WHAT WE WILL SEE FOR THIS WEDNESDAY. AT LEAST THAT IS
WHAT THE MODELS ARE INDICATING AT THIS POINT. SO WE COULD SEE FIRE
WEATHER CONCERNS ONCE AGAIN FOR SATURDAY (SEE FIRE WEATHER SECTION
BELOW FOR MORE DETAILS). EVEN COOLER TEMPERATURES EXPECTED WITH THIS
STRONGER WEEKEND SYSTEM WITH HIGHS FOR TUCSON POSSIBLY HOVERING
AROUND THE 80 DEGREE MARK FOR BOTH SATURDAY AND SUNDAY.

THIS SYSTEM WILL RAPIDLY EJECT TO THE NORTHEAST OVER THE FRONT RANGE
OF THE ROCKIES/CENTRAL PLAINS BY EARLY SUNDAY MORNING. RIDGING WILL
BUILD IN BEHIND THE SYSTEM THROUGH MONDAY WITH WARMING TEMPERATURES.

HIGH TEMPERATURES WILL BE 7 TO 10 DEGS ABOVE NORMAL THIS
AFTERNOON...THEN 1 TO 3 DEGS ABOVE NORMAL WEDNESDAY THROUGH FRIDAY.
THEREAFTER...HIGHS EXPECTED TO BE BELOW NORMAL....WITH THE COOLEST
DAY OCCURRING ON SUNDAY WITH READINGS AROUND 6 TO 8 DEGS BELOW
NORMAL. OTHERWISE...HIGHS ABOUT 3 TO 5 DEGS BELOW NORMAL. LOWS WILL
RANGE FROM 6 TO 8 DEGS ABOVE NORMAL WEDNESDAY MORNING...THEN 2 TO 3
DEGS ABOVE NORMAL THURSDAY THROUGH SATURDAY MORNINGS. THEREAFTER...
LOWS ABOUT 2 TO 3 DEGS BELOW NORMAL.

&&

.AVIATION...VALID THRU 24/12Z.
UPPER LEVEL TROUGH OFF THE NRN CALIFORNIA COAST WILL DIG SE-WARD
TODAY WHICH WILL USHER IN INCREASING HIGH CLOUDS. LOW/MID LEVEL S TO
SWRLY WINDS WILL INCREASE AHEAD OF THIS TROUGH WHICH WILL MIX DOWN
TO THE SFC AFTER 18Z. THEREFORE...EXPECT AFTERNOON/EVENING SFC WINDS
NEAR 15KTS AT ALL TERMINALS WITH GUST AROUND 25 KTS. THESE WINDS ARE
EXPECTED TO TAPER OFF QUICKLY AFTER SUNSET AS THE NOCTURNAL
INVERSION SETS IN. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...GENERALLY DRY AND WARM THROUGH FRIDAY.  AN UPPER
LEVEL TROUGH MOVING ACROSS THE WESTERN US TODAY AND WEDNESDAY WILL
RESULT IN GUSTIER WEST TO SOUTHWEST WINDS ACROSS SOUTHEAST ARIZONA.
SOUTHWEST WINDS WILL INCREASE THIS AFTERNOON WITH SUSTAINED 20 FT
WINDS GENERALLY PEAKING IN THE 15 TO 20 MPH RANGE LATE IN THE DAY
ACROSS MOST OF THE FORECAST AREA...JUST SHY OF RED FLAG CRITERIA.
MINIMUM RH LEVELS WILL GENERALLY BE IN THE 10-15% RANGE WITH
SLIGHTLY HIGHER VALUES IN THE MOUNTAINS AND A FEW SINGLE DIGITS IN
THE VALLEYS.

THE TROUGH AXIS WILL PASS ACROSS THE AREA WEDNESDAY.. MINIMUM RH
LEVELS WILL BE SIMILAR TO TODAY. WINDS GUIDANCE HAS CONTINUED TO
TREND DOWN WHICH MAKES SENSE GIVEN THE OVERALL TRACK OF THE TROUGH
AND THE MID/UPPER LEVEL GRADIENT DECREASING AS THE TROUGH EXITS THE
STATE. STILL...WINDS WILL BE STRONG ENOUGH OUT EAST TO WARRANT FIRE
WEATHER WATCH CURRENTLY IN EFFECT. HOWEVER...NOT CONFIDENT ENOUGH TO
UPGRADE THE WATCH AT THIS TIME.

MORE TYPICAL WINDS EXPECTED THURSDAY WITH SOME AFTERNOON GUSTS DUE
TO DAYTIME HEATING BEFORE ANOTHER SYSTEM MOVES INTO THE WESTERN US
BY THIS WEEKEND. WINDS WILL BEGIN TO INCREASE FRIDAY WITH EVEN
STRONGER WINDS LIKELY THIS WEEKEND. WIDESPREAD CRITICAL FIRE WEATHER
CONDITIONS ARE POSSIBLE ESPECIALLY SATURDAY AFTERNOON AS THE TROUGH
AXIS SLIDES ACROSS THE REGION.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...FIRE WEATHER WATCH FROM WEDNESDAY
       AFTERNOON THROUGH WEDNESDAY EVENING FOR AZZ152-153.

&&

$$

VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON

PUBLIC...MOLLERE
FIRE WEATHER/AVIATION...HUMPHREYS/MEADOWS






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