Area Forecast Discussion
Issued by NWS Tucson, AZ

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KTWC 271635
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
935 AM MST FRI FEB 27 2015

.SYNOPSIS...A STRONG LOW PRESSURE SYSTEM DEVELOPING ALONG THE WEST
COAST WILL BRING GUSTY WINDS TO THE AREA TODAY AND SATURDAY FOLLOWED
BY PERIODS OF VALLEY RAIN AND MOUNTAIN SNOWS LATER THIS WEEKEND INTO
THE MIDDLE OF NEXT WEEK.  ABOVE NORMAL TEMPERATURES TODAY AND
SATURDAY WILL GIVE WAY TO MUCH BELOW NORMAL HIGH TEMPERATURES BY
EARLY NEXT WEEK.

&&

.DISCUSSION...SHORT TERM FORECAST LOOKED ON TRACK. STILL SOME
UNCERTAINTY ON THE TIMING OF THE STORM SYSTEM FOR LATER THIS WEEKEND
INTO THE MIDDLE OF NEXT WEEK. A QUICK LOOK AT THE MORNING MODEL
SOLUTIONS SUGGESTED THAT THIS INITIAL SYSTEM WILL TRACK FARTHER
SOUTH TO A POSITION JUST OFF THE SOUTHERN CALIFORNIA COAST BY MONDAY
MORNING. THIS POSITIONING WOULD KEEP THE PRECIPITATION CHANCES WEST
AND NORTH OF MUCH OF SOUTHEAST ARIZONA ON SUNDAY WITH THE BEST
CHANCES STARTING UP ON MONDAY. PLEASE REFER TO THE PREVIOUS
DISCUSSION IN THIS PRODUCT FOR MORE DETAILS ON THE UPCOMING PERIOD
OF UNSETTLED WEATHER.

&&

.AVIATION...VALID THRU 28/18Z.
VFR CONDITIONS WILL PREVAIL WITH A FEW TO OCCASIONALLY BKN CLOUDS
GENERALLY AOA 20K FT AGL. SURFACE WIND WILL BE BECOMING SWLY AND
INCREASING THIS AFTERNOON TO AROUND 13-22 KTS WITH GUSTS RANGING
FROM 20-30 KTS...WITH THE STRONGEST WINDS NEAR THE KDUG AND KALK
TERMINALS. WINDS DECREASING AGAIN AFTER SUNSET BUT GENERALLY SOUTH
AT 8-15 KNOTS THROUGH EARLY SATURDAY MORNING BEFORE PICKING UP AGAIN
SATURDAY AFTERNOON. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...DRY CONDITIONS WILL CONTINUE TODAY. A STRENGTHENING
STORM SYSTEM WEST OF THE AREA WILL PRODUCE GUSTY WINDS IN EXCESS OF
20 MPH...ESPECIALLY ACROSS THE HIGHER TERRAIN AND NEAR THE
INTERNATIONAL BORDER. TODAY WILL ALSO BE THE LAST DAY WITH ABOVE
NORMAL TEMPERATURES FOR A WHILE...ALONG WITH MINIMUM RH VALUES IN
THE TEENS. EXPECT STRONGER WINDS SATURDAY...WITH 20-FOOT WIND SPEEDS
GENERALLY FROM THE SOUTHWEST AT 15-25 MPH ALONG WITH GUSTS UP TO 35
MPH. THE STRONGEST WIND SPEEDS WILL OCCUR ACROSS THE HIGHER TERRAIN.
PRECIPITATION CHANCES WILL INCREASE ACROSS THE AREA BEGINNING
SATURDAY WITH WIDESPREAD VALLEY RAIN AND MOUNTAIN SNOW BY EARLY
MONDAY AND CONTINUING THROUGH EARLY TUESDAY. ISOLATED TO SCATTERED
VALLEY RAIN AND MOUNTAIN SNOW SHOWERS WILL CONTINUE TUESDAY AND
WEDNESDAY...WITH THE BEST CHANCE OF PRECIPITATION TO OCCUR EAST OF
TUCSON.

&&

.PREV DISCUSSION...PATTERN TRANSITION TAKING PLACE AS A DEEP TROUGH
SETTLES DOWN THE WEST COAST WHICH WILL MAKE FOR INTERESTING WEATHER
THROUGH AT LEAST THE MIDDLE OF NEXT WEEK.  FOR NOW...NW FLOW OVER
THE AREA BECOMING WEST TO SOUTHWEST THROUGH THE DAY WITH THE
MID-LEVEL GRADIENT GRADUALLY TIGHTENING THROUGH SATURDAY.  THEREFORE
EXPECT A DECENT SW BREEZE TO DEVELOP THIS AFTERNOON WITH A GOOD
AMOUNT OF SUNSHINE AND ANOTHER DAY OF WARMER THAN NORMAL HIGH
TEMPERATURES.

FOR SATURDAY...THE FLOW ALOFT BECOMES MORE SW AND PICKS UP SPEED A
BIT FOR STRONGER WINDS...PUSHING PRETTY CLOSE TO WIND ADVISORY
VALUES SOUTHERN COCHISE COUNTY.  THE BULK OF THE MOISTURE WITH THE
DEEPENING TROUGH OVER CALIFORNIA WILL REMAIN TO THE NORTH AND WEST
OF OUR AREA SO KEPT CHANCE OF SHOWERS TO THE WEST AND NORTHERN
PERIPHERY OF OUR FORECAST AREA.  MAIN SHOT WILL BE OVER THE WHITE
MOUNTAINS ALTHOUGH SNOW LEVELS WILL BE RATHER HIGH AT THAT POINT.
AFTERNOON TEMPERATURES WILL BE NEAR TO SLIGHTLY ABOVE NORMAL
DEPENDING ON JUST HOW MUCH SUN CAN SNEAK THROUGH THE CLOUD COVER.

SUNDAY COULD END UP BEING NOT ALL THAT WET DUE TO THE FACT THAT AS
THE TROUGH DEEPENS THE BAND OF MOISTURE IS LIKELY TO CONSOLIDATE
WITH A DRY SLOT JUST TO ITS EAST.  NEARLY ALL OPERATIONAL MODELS
POINT TO THIS SCENARIO WITH THE MAIN BAND OF SHOWERS TO OUR WEST.
DECIDED TO TREND THAT WAY AND DROPPED THE POPS FROM A TUSCON TO
SAFFORD LINE SOUTHEASTWARD.  ENDED UP WITH SLIGHT CHANCE OVER TUCSON
AND ZIP ACROSS COCHISE COUNTY AND BLENDED TO HIGH CHANCE TO THE WEST
TO MATCH UP WITH OUR NEIGHBORS.  BEGINNING TO LOOK LIKE SUNDAY MAY
END UP DRY FROM TUCSON SOUTHEAST.  WITH A DECENT GRADIENT REMAINING
OVER THE REGION THE SOUTH TO SOUTHWEST BREEZE WILL CONTINUE WITH
NEAR NORMAL TEMPS.

BEYOND THAT THINGS ARE COMPLICATED AS THE MAIN VORT CENTER IN THE
TROUGH LIFTS ACROSS THE AREA MONDAY WHILE ANOTHER STRONG CENTER
DIVES DOWN THE BACK SIDE OF THE TROUGH AND ROUNDS THE BOTTOM OF THE
LONGWAVE TROUGH TUESDAY.  AS A RESULT...GOOD BET FOR PERIODS OF RAIN
AND MOUNTAIN SNOWS SUNDAY NIGHT INTO TUESDAY WITH DECENT
ACCUMULATIONS EXPECTED THROUGH THAT TIME FRAME.  WE WON`T HAVE
STEADY PRECIPITATION THROUGH THE ENTIRE PERIOD BUT RATHER PERIODS OF
PRECIPITATION AS BANDS MOVE THROUGH.

SNOW LEVELS WILL BE DROPPING FROM AROUND 8000 FEET SUNDAY EVENING TO
AROUND 5500 FEET MONDAY NIGHT AND THEN LINGER IN THE 5-6000 FT RANGE
INTO WEDNESDAY.  AT THIS POINT STILL LOOKING AT 0.50-1.25 RAIN
(STORM TOTAL) IN THE VALLEYS WITH THE LOWER VALUES ACROSS SE COCHISE
COUNTY AND HIGHER VALUES WEST AND NORTH OF TUCSON.  FOR STORM TOTAL
SNOW...CURRENT ESTIMATES ARE NEAR A FOOT ATOP MT LEMMON AND 1.5 FT
ATOP MT GRAHAM AND 1-2.5 FT IN THE WHITE MOUNTAINS.  WINDS WILL BE
LOWER MONDAY AND TUESDAY AS THE GRADIENT WEAKENS WITH TEMPERATURES A
GOOD 10 DEGREES BELOW NORMAL BOTH DAYS.

WEDNESDAY IS A GOOD QUESTION MARK AT THE MOMENT AS THE ECMWF AND THE
CANADIAN MODELS LINGER THE TROUGH OVER THE REGION THROUGH THE DAY
WITH CONTINUED SHOWERS WHILE THE GFS IS MORE PROGRESSIVE WITH THE
SYSTEM AND IS DRY THAT DAY.  I MAINTAINED THE THREAT OF SHOWERS
THROUGH WEDNESDAY AND TRIMMED AFTERNOON TEMPS A BIT WITH VALUES
REMAINING NEARLY 10 DEGREES BELOW NORMAL.  CERNIGLIA

&&

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

&&

$$

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









USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.