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

000
FXUS65 KTWC 190920
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
220 AM MST SAT APR 19 2014

.SYNOPSIS...A PACIFIC LOW PRESSURE SYSTEM WILL BRING A CHANCE OF
SHOWERS AND THUNDERSTORMS THROUGH THE WEEKEND...WITH THE BEST CHANCE
FOR MEASURABLE RAIN AND A FEW LIGHTNING STRIKES OCCURRING THIS
AFTERNOON. AFTER SEASONAL TEMPERATURES TODAY...A STRONG WARMING
TREND WILL BEGIN SUNDAY AND CONTINUE INTO THE FIRST PART OF THE NEW
WORK WEEK.

&&

.DISCUSSION...WATER VAPOR IMAGERY AND 19/00Z UPPER-AIR PLOTS SHOW AN
UPPER LOW IN THE GENERAL VICINITY OF SOUTHERN CALIFORNIA...SOUTHWEST
ARIZONA AND THE NORTHERN BAJA PENINSULA. SOUTHERLY FLOW AHEAD OF
THIS LOW WILL CONTINUE TO KEEP AMPLE MOISTURE IN PLACE TODAY.
YESTERDAY EVENINGS KTWC SOUNDING SHOWED A PRECIPITABLE WATER VALUE
OF 0.80 INCHES. NAM12 MODEL FORECAST SOUNDINGS KEEP PW`S AROUND
THREE QUARTERS OF AN INCH TODAY...WITH THE GFS A TAD LOWER. AT ANY
RATE...WITH THE LOW EXPECTED TO MOVE ACROSS SOUTHERN ARIZONA TODAY
THERE IS PLENTY OF MOISTURE TO JUSTIFY SCATTERED TYPE POPS FOR THE
DESERTS/VALLEYS AND LIKELY POPS FOR THE MOUNTAINS TODAY. MADE A FEW
MINOR TWEAKS TO THE POP GRIDS TODAY THROUGH LATE SUNDAY. WILL SEE
SOME ISOLATED LIGHTNING STRIKES WITH THE SHOWERS/TSTMS THAT DEVELOP
THIS AFTERNOON AND EVENING.

THE SYSTEM WILL BEGIN TO KICK TO THE EAST THIS EVENING AND THE
TROUGH AXIS WILL BE OVER EASTERN NEW MEXICO BY EARLY SUNDAY MORNING.
BY LATE SUNDAY AFTERNOON THE TROUGH WILL BE OVER THE CENTRAL PLAINS
WITH A SECONDARY WEAKER TROUGH AXIS OVER EXTREME SOUTHEAST ARIZONA
AND NORTHEAST MEXICO. THERE WILL STILL BE ENOUGH RESIDUAL MOISTURE
IN PLACE TO JUSTIFY SLIGHT CHANCE POPS SUNDAY AFTERNOON...MAINLY FOR
THE MOUNTAINS BETWEEN TUCSON AND THE NEW MEXICO BORDER.

FOR MONDAY RIDGING WILL BUILD IN BEHIND THIS SYSTEM FOR A RAPID
WARMUP IN HIGH TEMPERATURES AND THIS WILL CONTINUE INTO TUESDAY
BEFORE ANOTHER PACIFIC SYSTEM MOVES INTO THE WEST COAST. THIS SYSTEM
WILL MOVE BY TO OUR NORTH LATE TUESDAY INTO EARLY WEDNESDAY...BUT
MODELS ARE SHOWING SIGNIFICANT DIFFERENCES WITH THE GFS FASTER THAN
THE ECMWF AND KEEPS THE ENERGY FARTHER NORTH THAN THE EURO. THE
BOTTOM LINE IS A DRY FORECAST THIS WEEK...BUT WE WILL SEE WINDS
INCREASE TUESDAY AND WEDNESDAY AS THIS SYSTEM MOVES BY TO OUR
NORTH.

HIGH TEMPERATURES WILL BE NEAR NORMAL TODAY...THEN WELL ABOVE NORMAL
HIGHS THROUGH THE REMAINDER OF THE FORECAST PERIOD...BUT THE WARMEST
DAYS WILL OCCUR MONDAY AND TUESDAY WHEN HIGHS WILL GENERALLY BE 8 TO
10 DEGS ABOVE NORMAL. OTHERWISE...HIGHS RUNNING 2 TO 4 DEGS ABOVE
NORMAL EACH DAY. LOW TEMPS WILL BE ABOVE NORMAL THROUGH THURSDAY
MORNING...THEN NEAR NORMAL FOR FRIDAY. THE WARMEST MORNINGS WILL
OCCUR MONDAY AND TUESDAY...WHEN LOWS WILL RANGE FROM 6 TO 9 DEGS
ABOVE NORMAL. OTHERWISE...LOWS 2 TO 5 DEGS ABOVE NORMAL.

&&

.AVIATION...VALID THRU 20/06Z.
UPPER LEVEL LOW PRESSURE OVER SOUTHERN CALIFORNIA....SOUTHWEST
ARIZONA AND NORTHERN BAJA WILL MOVE ACROSS SOUTHERN ARIZONA TODAY...
PRODUCING OVERCAST CLOUD DECKS MOSTLY ABOVE 10K FT AND ISOLD TO SCT
-SHRA WITH ISOLD -TSRA. WINDS GUSTS AROUND 35 KTS NEAR THESE SHOWERS
AND STORMS. MID AND UPPER LEVEL CLOUD DECKS NOT FULLY CLEARING OUT
UNTIL THE LOW MOVES FARTHER EAST ON SUNDAY. ERRATIC THUNDERSTORM
OUTFLOWS WILL DOMINATE NORMAL DIURNAL WIND PATTERNS. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...A WEAK UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE
ACROSS SOUTHERN ARIZONA TODAY THROUGH EARLY SUNDAY. ENOUGH MOISTURE
IS PRESENT WITH THIS SYSTEM FOR SCATTERED SHOWERS WITH ISOLATED
THUNDERSTORMS MAINLY THIS AFTERNOON....WITH A BETTER THREAT FOR THE
MOUNTAINS. RAINFALL AMOUNTS ARE EXPECTED TO BE LIGHT FOR MOST VALLEY
AND DESERT LOCATIONS. MOUNTAIN PRECIPITATION GENERALLY AROUND A
QUARTER TO PERHAPS A THIRD OF AN INCH. THE MAIN CONCERN WILL BE THE
POTENTIAL FOR GUSTY AND ERRATIC WINDS ASSOCIATED WITH THE SHOWERS
AND THUNDERSTORMS. A FEW SHOWERS COULD LINGER NEAR THE NEW MEXICO
BORDER ON SUNDAY WITH A RETURN TO DRY CONDITIONS EARLY NEXT WEEK.

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

&&

$$

MOLLERE

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.