Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 190333
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
840 PM MST FRI APR 18 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 SATURDAY.
AFTER SEASONAL TEMPERATURES AGAIN SATURDAY...A STRONG WARMING TREND
WILL BEGIN SUNDAY AND CONTINUE INTO THE FIRST PART OF THE NEW WORK
WEEK.

&&

.DISCUSSION...PACIFIC LOW PUSHING SLOWLY INTO SOUTHWEST ARIZONA THIS
EVENING WITH ISOLATED CONVECTION ON EASTERN PERIPHERY THROUGH OUR
CWA. SOLID MOISTURE INCREASE FOR APRIL WITH PRECIPITABLE WATER
VALUES CLIMBING INTO THE .8 INCH RANGE ACROSS SE AZ AND SURFACE
DEWPTS IN THE 40S. WEAK MOISTURE CONVERGENCE AND A VORT SPOKE
ROTATING UP FROM NORTHWEST MEXICO WILL KEEP A CHANCE OF CONVECTION
GOING OVERNIGHT. IMPULSE PUSHES ACROSS ARIZONA SATURDAY AFTERNOON
WITH A LITTLE BETTER ORGANIZATION THAN TODAY. STILL EMPHASIZING
GUSTY OUTFLOW WINDS OVER SIGNIFICANT PRECIP...ALTHOUGH THEY WILL
TEND TO BE A LITTLE WETTER SATURDAY COMPARED TO FRIDAY.

&&

.PREV DISCUSSION... EXPECT CHANCES FOR SHOWER AND TSTM ACTIVITY TO
CONTINUE OVERNIGHT ALTHOUGH THUNDER CHANCES SHOULD SUBSIDE WITH THE
LOSS OF DAYTIME HEATING. AS UPPER LOW DRAWS NEAR...THE BEST CHANCE
FOR THUNDERSTORMS TO OCCUR IS LIKELY TO BE SATURDAY AFTN/EVE.
OVERALL...DO NOT EXPECT SIGNIFICANT RAIN AMOUNTS BUT SOME LOCATIONS
MIGHT SQUEEZE OUT A QUARTER OF AN INCH OR SO.  SHOWERS COULD LINGER
OR REDEVELOP SUNDAY AFTERNOON NEAR THE NM BORDER ON THE BACK SIDE OF
THE UPPER LOW.

TEMPERATURES WILL BEGIN TO WARM BACK UP SUNDAY AND PEAK MONDAY AND
TUESDAY UNDER A RIDGE OF HIGH PRESSURE. A TROUGH CROSSING THE
NRN/CENTRAL ROCKIES TUE-WED WILL BRING GUSTY WINDS TO SE AZ BOTH
DAYS. TEMPERATURES WILL DROP OFF SLIGHTLY AS THE TROUGH PASSES...BUT
ABOVE NORMAL READINGS WILL PREVAIL FOR THE LATTER HALF OF NEXT WEEK.

&&

.AVIATION...VALID THRU 20/03Z.
UPPER LEVEL LOW PRESSURE OVER SOUTHERN CALIFORNIA WILL MOVE ACROSS
SOUTHERN ARIZONA TONIGHT AND SATURDAY...PRODUCING OVERCAST CLOUD
DECKS MOSTLY ABOVE 10K FT AND ISOLD TO SCT -SHRA WITH ISOLD -TSRA.
WINDS GUSTS AROUND 35 KTS NEAR THESE SHOWERS. CHANCES FOR
-SHRA/-TSRA ARE BETTER ON SATURDAY AFTERNOON WITH GUSTS NEAR 35KTS.
MID AND UPPER LEVEL CLOUD DECKS NOT FULLY CLEARING OUT UNTIL THE LOW
MOVES FURTHER 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 TONIGHT THROUGH EARLY SUNDAY. ENOUGH
MOISTURE IS PRESENT WITH THIS SYSTEM FOR SCATTERED SHOWERS WITH
ISOLATED THUNDERSTORMS THROUGH SATURDAY. RAINFALL AMOUNTS ARE
EXPECTED TO BE LIGHT FOR MOST VALLEY AND DESERT LOCATIONS. MOUNTAIN
PRECIPITATION GENERALLY A QUARTER INCH OR LESS. 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.

&&

$$

MEYER/DROZD/SAMPSON

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