Severe Thunderstorm Warning 120, NWS Tucson, AZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
915 PM MST TUE OCT 20 2015

.SYNOPSIS...A LOW PRESSURE SYSTEM MOVING SLOWLY ACROSS SOUTHERN
ARIZONA WILL CONTINUE TO BRING A CHANCE OF SHOWERS AND THUNDERSTORMS
AREA-WIDE TONIGHT INTO WEDNESDAY. A DRYING TREND WILL START THURSDAY
INTO THE WEEKEND ALONG WITH WARMER TEMPERATURES.

&&

.DISCUSSION...THE LOW CONTINUES TO PUSH SLOWLY ACROSS SOUTHERN
ARIZONA...STILL WEST OF OUR AREA. REINFORCING ENERGY ROUNDING UNDER
THE BOTTOM OF THE LOW IS NOW LIFTING NORTH INTO THE EASTERN FLANK OF
THE LOW AND INTO OUR AREA OVERNIGHT. WE INCREASED OUR CHANCE OF
STORMS OVERNIGHT AS WE DEFY NORMAL DIURNAL TRENDS WITH A LOW LEVEL
MOISTURE CONVERGENT FIELD AND SOLID DYNAMICS CONTINUING FROM SANTA
CRUZ THROUGH EASTERN PIMA AND INTO PINAL COUNTY TONIGHT. PLEASE SEE
THE PREVIOUS DISCUSSION FOR ADDITIONAL DETAILS.

&&

.AVIATION...VALID THRU 22/00Z.
A LOW PRESSURE SYSTEM WILL BE MOVING ACROSS SRN AZ THRU WEDNESDAY
NIGHT. EXPECT ISOLD TO SCT SHRA/TSRA THROUGH THE PERIOD.21/12Z. SOME
OF THESE STORMS WILL BE CAPABLE OF PRODUCING WIND GUSTS OF 40-50
KTS. EXPECT MVFR CONDS WITH STRONGEST TSTMS. SFC WIND AWAY FROM THE
STORMS S-SW AT 10-16 KTS WITH GUSTS UP TO 25 KTS. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...SCATTERED SHOWERS AND THUNDERSTORMS TONIGHT INTO
WEDNESDAY AS A LOW PRESSURE SYSTEM MOVES ACROSS THE AREA.  THIS
SYSTEM WILL ALSO BRING COOLER TEMPERATURES AND BREEZY CONDITIONS.
ISOLATED SHOWERS AND THUNDERSTORMS WILL OCCUR MAINLY EAST OF TUCSON
ON THURSDAY.  DRY CONDITIONS AND A SLIGHT WARMING TREND WILL RETURN
FRIDAY AND CONTINUE THROUGH THE UPCOMING WEEKEND.  20-FT WINDS WILL
BE SOUTH TO SOUTHWEST AROUND 15 MPH WITH GUSTS TO 30 MPH THIS
AFTERNOON AND EARLY EVENING.  WINDS WILL THEN BE MAINLY TERRAIN
DRIVEN AND LESS THAN 15 MPH INTO THIS WEEKEND.

&&

.PREV DISCUSSION...A NICE TRANSITION SEASON LOW OVER WESTERN AND
SOUTHWESTERN ARIZONA INTO FAR NORTHWEST MEXICO. WATER VAPOR IMAGERY
SHOWING THIS NICELY WITH THE MAIN LOW CENTER NEAR YUMA AND TWO
ADDITIONAL IMPULSES EMBEDDED AROUND THE LOW CENTER. ONE CARVING
SOUTH DOWN THE BACK SIDE AND INTO THE BASE...AND ANOTHER ROTATING UP
INTO THE EAST AND NORTHEAST AREAS OF THE LOW CIRCULATION. WITH VERY
LITTLE HIGHER LATITUDE SUPPORT...THESE FEATURES WILL SLOWLY PHASE
ACROSS THE AREA OVER THE NEXT 48 HOUR. THIS WILL BUCK NORMAL DIURNAL
TRENDS WITH SHOWERS AND THUNDERSTORMS POSSIBLE AT ANY TIME INTO
WEDNESDAY NIGHT. A WEAK MOISTURE CONVERGENT FIELD WILL PUT SANTA
CRUZ AND EASTERN PIMA COUNTY INTO THE ACTION LATE THIS AFTERNOON AND
THIS EVENING.

THE LOW WILL SHEAR INTO THE BASE OF AN APPROACHING TROUGH ON
THURSDAY WITH A DRYING TREND FROM THE WEST.

THE OVERALL LARGE SCALE DRYING TREND WILL THEN CONTINUE INTO THIS
WEEKEND AS A LOW AMPLITUDE RIDGE PHASES IN FROM THE WEST.
AS THIS HAPPENS TEMPERATURES WILL CLIMB BACK ABOVE AVERAGE BY
SATURDAY AND SUNDAY.

&&

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

&&

MEYER/CERNIGLIA

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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TUCSON AZ
938 PM MST TUE OCT 20 2015

AZZ505-210515-
SOUTH CENTRAL PINAL COUNTY INCLUDING ELOY/PICACHO PEAK STATE PARK AZ-
938 PM MST TUE OCT 20 2015

...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL PINAL COUNTY UNTIL
1015 PM MST...

AT 936 PM MST...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR
FRIENDLY CORNERS...MOVING NORTH AT 20 MPH.

HALF INCH HAIL AND WINDS IN EXCESS OF 45 MPH WILL BE POSSIBLE WITH
THIS STORM AS IT APPROACHES I-10 FROM THE SOUTH...WITH POSSIBLE
BLOWING DUST FOLLOWED BY LOCALLY HEAVY RAIN.

LOCATIONS IMPACTED INCLUDE...
ELOY...FRIENDLY CORNERS...PICACHO AND PICACHO PEAK.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND
TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS...FOR ADDITIONAL
INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE.

BLOWING DUST CAN QUICKLY REDUCE VISIBILITY...CAUSING ACCIDENTS THAT
MAY INVOLVE CHAIN COLLISIONS. IF DENSE DUST IS OBSERVED ACROSS A
ROADWAY...PULL YOUR VEHICLE OFF THE PAVEMENT AS FAR AS POSSIBLE TO
STOP. TURN OFF THE LIGHTS...SET THE EMERGENCY BRAKE...AND TAKE YOUR
FOOT OFF THE BRAKE PEDAL TO ENSURE TAIL LIGHTS ARE NOT ILLUMINATED.

&&

LAT...LON 3271 11128 3252 11139 3252 11159 3275 11163
      3280 11157
TIME...MOT...LOC 0436Z 181DEG 21KT 3258 11149

MEYER