Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 240929
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
230 AM MST MON NOV 24 2014

.SYNOPSIS...COOLER AND DRIER AIR INVADING FROM THE NORTH WILL SETTLE
OVER THE AREA AND COMBINE TO USHER IN COLDER OVERNIGHT LOWS TONIGHT
INTO WEDNESDAY MORNING. HIGH PRESSURE WILL BRING A STRONG WARMING
TREND THE SECOND HALF OF THE WEEK WITH A RATHER MILD THANKSGIVING.

&&

.DISCUSSION...MUCH DRIER AND COOLER AIRMASS SETTLING IN THIS MORNING
WITH 24 HOUR TEMPERATURE TRENDS DOWN 5 TO 7 DEGREES AND A DEW POINT
CRASH INTO THE TEENS AND SINGLE DIGITS.

WHEN ALL IS SAID AND DONE WITH A BIT MORE COLD AIR ADVECTION
TODAY...THE POTENTIAL OF THIS AIRMASS IS FOR THE COLDEST OVERNIGHT
LOWS OF THE SEASON SO FAR TONIGHT INTO TUESDAY MORNING. THE MAIN
MITIGATING FACTOR IS A LOW LEVEL EASTERLY GRADIENT SETTING UP A
RETURN FLOW SPILLING OVER FROM NEW MEXICO. IT WILL HAPPEN TUESDAY
MORNING...AND PRECISELY WHEN WILL DETERMINE IF TUCSON FREEZES OR
NOT. AS OF RIGHT NOW WE HAVE 34 FOR TIA TUESDAY MORNING WITH THE
EASTERLY WINDS KICKING IN AROUND 3 OR 4 AM PREVENTING A FREEZE. EVEN
IF THIS WORKS OUT THERE SHOULD BE ENOUGH AREAS AROUND EASTERN PIMA
COUNTY INCLUDING OUTLYING AND WIND SHELTERED AREAS AROUND TUCSON
METRO THAT MAY FREEZE TO WARRANT A FREEZE WATCH AS A HEADS-UP. ALSO
IT SHOULD BE NOTED IT WON`T TAKE MUCH WIND TO TAKE THE EDGE OFF...7
TO 10 MPH WOULD DO IT.

ELSEWHERE OUR TYPICAL COLD PRONE EASTERN VALLEY LOCATIONS INCLUDING
MOST OF COCHISE...SANTA CRUZ...GRAHAM AND GREENLEE COUNTIES (AND
PORTIONS OF EASTERN PINAL COUNTY) SHOULD EASILY REACH FREEZE AND/OR
HARD FREEZE LEVELS.

THIS COOLER AIR WILL SETTLE IN THROUGH WEDNESDAY MORNING BEFORE A
RIDGE PHASING IN FROM THE WEST BRINGS A STRONG WARMING TREND THE
SECOND HALF OF THE WEEK. RELATIVELY WARM TEMPERATURES BY THURSDAY
AND FRIDAY...AROUND 8-10 DEGREES ABOVE CLIMO WHICH PUTS TUCSON
AROUND 80 OR SO.

BOTH ECMWF AND GFS DEVELOPING A SOLID TROUGH FOR MOST OF THE REGION
DAYS 7-10 TO START DECEMBER. THAT WILL BE OUR NEXT SHOT AT ANY
SEASONAL WEATHER.

&&

AVIATION...VALID THRU 25/12Z.
GENERALLY LIGHT DIURNAL WINDS AND SKC THOUGH A FEW CIRRUS LEVEL
CLOUDS WILL SLIDE INTO THE AREA EARLY IN THE PERIOD.  AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...STRONG MID LEVEL WINDS WILL BE PRESENT THRU THE NEXT
24-36 HOURS WHICH WILL ALLOW FOR SLIGHTLY ELEVATED WINDS...
ESPECIALLY ACROSS THE GILA RIVER VALLEY AND HIGHER TERRAIN DURING
THE AFTERNOON/EVENING HOURS. TOMORROW MORNING A TIGHTENED PRESSURE
GRADIENT NEAR THE INTERNATIONAL BORDER WILL RESULT IN THE WINDS
STAYING UP. OTHERWISE...UPPER LEVEL HIGH WILL BE NEAR OR OVERHEAD
THRU THE FORECAST KEEPING THINGS RELATIVELY QUIET. THAT BEING
SAID...LATE THIS WEEKEND INTO EARLY NEXT WEEK AN UPPER TROUGH WILL
SLIDE INTO THE AREA AND BRING THE POTENTIAL FOR ELEVATED WINDS AND A
CHANCE OF PRECIPITATION.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...FREEZE WATCH TONIGHT INTO
     TUESDAY MORNING FOR AZZ504 INCLUDING EASTERN PIMA COUNTY.

&&

$$

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

MEYER/MEADOWS/CARLAW





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