Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 200400
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
900 PM MST MON JAN 19 2015

.SYNOPSIS...DRY CONDITIONS WITH UNSEASONABLY WARM DAYTIME
TEMPERATURES WILL CONTINUE THROUGH TUESDAY. A WEAK DISTURBANCE IS
EXPECTED TO BRING A FEW SHOWERS MAINLY NORTH AND EAST OF TUCSON
WEDNESDAY INTO THURSDAY. COOLER TEMPERATURES THE SECOND HALF OF THE
WEEK BEFORE ANOTHER WARMING TREND THIS WEEKEND.

&&

.DISCUSSION...WATER VAPOR IMAGERY AND 20/00Z UPPER-AIR PLOTS SHOW
NEARLY ZONAL FLOW ACROSS THE DESERT SOUTHWEST...WITH A WEAK
DISTURBANCE CURRENTLY MOVING THROUGH THE GREAT BASIN AND NORTHERN
ARIZONA. ANOTHER WEAK SYSTEM WILL DEVELOP OVER SOUTHERN CALIFORNIA
THROUGH LATE TUESDAY...RESULTING IN SOME HIGH CLOUDINESS STREAMING
OVERHEAD FROM TIME TO TIME.

CURRENT TEMPERATURES SEEM TO BE ON TRACK WITH RESPECT TO OVERNIGHT
LOWS...BUT WILL CONTINUE TO MONITOR. OTHERWISE...THE FORECAST FOR
THE REMAINDER OF TONIGHT IS IN GOOD SHAPE.

SEE PREVIOUS DISCUSSION BELOW FOR DETAILS REGARDING THE FORECAST
THROUGH EARLY NEXT WEEK.

&&

.AVIATION...VALID THRU 21/06Z.
EXPECT VFR CONDITIONS WITH PERIODS OF SCT CLOUDS AOA 20K FT AGL.
OTHERWISE...NORMAL DIURNAL WIND TRENDS GENERALLY LESS THAN 10 KTS.
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...DRY CONDITIONS WITH WELL ABOVE NORMAL DAYTIME
TEMPERATURES AND LIGHT WINDS WILL PREVAIL THROUGH TUESDAY. THERE IS
A SLIGHT CHANCE OF SHOWERS NORTH TO EAST OF TUCSON WEDNESDAY INTO
THURSDAY AS A WEAK SYSTEM MOVES ACROSS THE AREA. MUCH COOLER
TEMPERATURES WILL OCCUR THURSDAY FOLLOWED BY A WARMING TREND WITH
DRY CONDITIONS THIS WEEKEND. SOME LOCALLY GUSTY WINDS MAY OCCUR
FRIDAY INTO SATURDAY.

&&

.PREV DISCUSSION...DIRTY LOW AMPLITUDE RIDGE WITH PATCHES OF CIRRUS
LEVEL MOISTURE THICKENING FROM THE WEST AT TIMES OVER THE NEXT 24 TO
36 HOURS.

IN GENERAL WE`RE FINDING AN EQUAL BLEND OF THE NEW GFS13 AND ECMWF
MODELS CONTINUE TO WORK PRETTY WELL FOR MOST FEATURES THAT
INFLUENCE OUR AREA. THE FLOW SHOULD BUCKLE FIRST ACROSS THE NORTHERN
PLAINS OVER THE NEXT 48 HOURS...AND THEN DIG INTO A LARGER SCALE
MEAN TROUGH POSITION DOWNSTREAM BY 72 HOURS. THIS SHOULD ALLOW A
MODEST REINFORCEMENT TO WEAK ENERGY UNDERCUTTING THE NEW MEAN RIDGE
POSITION JUST OFFSHORE IN THE EASTERN PACIFIC. AS IT PUSHES IN
ACROSS ARIZONA IT SHOULD PICK UP SOME ENERGY BUT PROBABLY NOT IN
TIME TO PICK UP A SIGNIFICANT SOUTHERLY COMPONENT MOISTURE FETCH
UNTIL IT`S ALREADY DOWNSTREAM OF OUR POSITION. NEVER THE LESS...A
FEW SHOWERS WILL WORK INTO THE FORECAST WEDNESDAY INTO THURSDAY
MAINLY EAST OF TUCSON NEAR HIGHER TERRAIN AND CLOSER TO THE NEW
MEXICO BORDER.

SOME COOLING WITH THESE FEATURES BY THURSDAY AND FRIDAY...BACK TO
NEAR CLIMO.

FRONT SIDE OF ANOTHER RIDGE PHASING IN FROM THE WEST BY THIS
WEEKEND. LOOKS KIND OF DIRTY WITH PATCHES OF SUBTROPICAL MOISTURE
BUT NO SIGNIFICANT SENSIBLE WEATHER.

&&

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

&&

$$

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

CURRENT DISCUSSION...MOLLERE
PREVIOUS DISCUSSION...MEYER/HUMPHREYS





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