Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 180331
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
831 PM MST FRI APR 17 2015

.SYNOPSIS...COOL CONDITIONS WILL REMAIN IN PLACE TONIGHT...BUT NOT
QUITE AS COLD AS LAST NIGHT. SOME OF THE COLDEST VALLEY LOCATIONS
WILL APPROACH FREEZING AGAIN SATURDAY MORNING. DRY CONDITIONS WITH A
WARMING TREND THIS WEEKEND INTO THE MIDDLE OF NEXT WEEK. ANOTHER
ROUND OF GUSTY WINDS IS EXPECTED BY WEDNESDAY OR THURSDAY OF NEXT
WEEK AS A SYSTEM APPROACHES FROM THE WEST.

&&

.DISCUSSION...SATELLITE IMAGERY WAS SHOWING CLEAR SKIES LATE THIS
EVENING ACROSS MUCH OF SOUTHEAST ARIZONA. JUST A FEW CLOUDS PASSING
THROUGH GRAHAM AND GREENLEE COUNTIES AT THIS TIME. CURRENT FORECAST
LOOKED ON TRACK...SO NO UPDATES NECESSARY THIS EVENING. PLEASE SEE
THE ADDITIONAL SECTIONS FOR MORE DETAILS.

&&

.AVIATION...VALID THRU 19/06Z.
VFR CONDITIONS THROUGH THE PERIOD. SKIES WILL BE SKC FOR THE MOST
PART WITH A FEW CLOUDS AOA 15K FT POSSIBLE FROM TIME TO TIME. LIGHT
AND VARIABLE WINDS WILL THEN OCCUR UNTIL AROUND 18/16Z.
THEREAFTER...EXPECT NWLY WINDS AT 12-16 KTS AND GUSTS TO 22 KTS AT
MOST LOCATIONS...WITH THE EXCEPTION OF KSAD WHERE SPEEDS OF 13-18
KTS AND GUSTS TO 30 KTS WILL BE POSSIBLE. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...DRY CONDITIONS WILL PREVAIL INTO THE MIDDLE OF NEXT
WEEK. IN GENERAL...20-FOOT WINDS EAST OF TUCSON DURING THE AFTERNOON
HOURS THROUGH THE WEEKEND WILL BE NORTHWESTERLY AT 12-16 MPH WITH
GUSTS OF 20-25 MPH. THE EXCEPTION IS SATURDAY AFTERNOON...WHEN WINDS
OF 15-20 MPH AND GUSTS TO 35 MPH ARE POSSIBLE IN THE GILA RIVER
VALLEY INCLUDING SAFFORD. COMBINED WITH DEWPOINTS IN THE 10-20
PERCENT RANGE...SPOTTY AND BRIEF RED FLAG CONDITIONS MAY OCCUR. LESS
WIND IS ANTICIPATED EARLY NEXT WEEK BEFORE ANOTHER ROUND OF GUSTY
WINDS AND PERHAPS SOME RAIN MAY OCCUR LATE NEXT WEEK AS ANOTHER
WEATHER SYSTEM APPROACHES FROM THE WEST.

&&

.PREV DISCUSSION...CLEAR...DRY AND COOL CONDITIONS EXPECTED
OVERNIGHT FOR MOST SE ARIZONA LOCATIONS. THE GOOD RADIATIONAL
COOLING CONDITIONS WILL ALLOW SOME VALLEY LOCATION TO FALL BELOW
FREEZING...BUT THE TEMPERATURES SHOULD NOT BE AS COLD AS LAST NIGHT.

RISING HEIGHTS TO COMMENCE NOW THAT THE UPPER LOW IS MOVING EAST
ACROSS NORTHERN NEW MEXICO. THIS WILL TRANSLATE TO A STEADY WARMING
TREND THROUGH MID WEEK. IN THE MEANTIME...A LOW PRESSURE SYSTEM WILL
BEGIN TO DEEPEN IN THE GULF OF ALASKA THROUGH EARLY NEXT WEEK. THE
GFS/ECMWF/CANADIAN ARE ALL SHOWING SIMILAR SOLUTIONS THROUGH MID
WEEK. THEY ALL SUGGEST A SHORT WAVE WILL TRAVERSE AROUND THE LOW
OVER ALASKA AND DEEPEN INTO A STRONGER WAVE THAT DIGS SOUTH OVER
CALIFORNIA. AS THE UPPER RIDGE SLIDES EAST LATE WEDNESDAY...THE
TROUGH IS ABLE  TO SLIDE INTO ARIZONA. FROM THAT POINT...TROUGHING
WILL BE THE DOMINANT PATTERN MOST LIKELY THROUGH THE WEEKEND.
HOWEVER...THIS IS WHERE THE MODELS BEGIN TO DIVERGE WITH THE GFS
BEING MORE PROGRESSIVE AND THE ECMWF THE SLOWER SOLUTION.

CURRENTLY INCLINED TO LEAN TOWARD THE ECMWF GIVEN THAT IT MATCHES UP
WELL WITH SEVERAL GEFS ENSEMBLE MEMBERS AND THE ENSEMBLE MEAN...AND
THE OPERATIONAL GFS IS TRENDING TOWARD THE FASTER OUTLIER SOLUTIONS.
THE NAEFS ENSEMBLE MEAN ALSO CLOSE TO THE ECMWF. I SHOULD POINT OUT
THAT IF THE GFS VERIFIES...HIGH TEMPS ON THURSDAY WILL BE UPWARDS OF
15 TO 20 DEGREES BELOW NORMAL AND MANY VALLEY LOCATIONS WOULD BE
UNDER THE THREAT OF FREEZING TEMPS FRIDAY OR SATURDAY MORNING.

THE OTHER CONCERN WILL BE WIND. THE TIGHT HEIGHT GRADIENTS
ASSOCIATED WITH THIS TROUGH WILL WARRANT CONCERN FOR THE FIRE
COMMUNITY OUTSIDE OF OUR MORE TYPICAL DIURNAL GUSTINESS.

JJB

&&

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


&&

$$

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