Special Weather Statement, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
245 PM MST MON AUG 8 2016

.SYNOPSIS...A few thunderstorms around the area again this afternoon
along with above average temperatures. The big story this week is
the increasing potential for heavy rain and possible flash flooding.
A deep tropical surge of moisture is expected across the region
Tuesday and Wednesday from moisture associated with Tropical Storm
Javier. This will not only result in a significant increase in the
coverage of showers and thunderstorms late Tuesday into Thursday,
but increase the possibility for heavy rainfall.

&&
.DISCUSSION...The upper pattern is currently defined by an upper
high in NE Sonora/NW Chihuahua/SW New Mexico this morning with a
larger scale upper trough along the west coast. In addition...
Tropical Storm Javier, which will play a major role in our weather
this week, is positioned just south of the tip of the Baja.

The NHC places it track up the western side of the Baja the next
couple of days, up to the Baja Spur, then stalls out. Given the weak
shear environment and warmer waters it is moving over, it should
continue to intensify over the next 24 hours, but still remain below
hurricane thresholds. Once this feature stalls...the lower levels
separate out and slowly drift west. Regardless, it is not the
Tropical Storm itself that is the concern, but the deep moisture
loosely associated with this system advecting into Southeast Arizona
over the next several days. The first sign of this moisture surge
will come about Tuesday morning up the Gulf and spill into the lower
deserts of SW AZ. More pronounced moisture push will move into the
rest of the area Tuesday night and Wednesday with PW values ranging
between 1.75 and 2.00 inches.

So...we will have plenty of moisture to work with which is one major
ingredient for the potential for heavy rain/flash flooding. The big
issue though is to determine the location and strength of any other
feature that will aid storm development. An upper disturbance in
phase with Tropical Storm Javier on the periphery of the upper high
is expected to rotate around the high and move into Southeast Arizona
Tuesday night and Wednesday. This will be the main feature our
moisture will have to work with. Given the current models...this is
still expected to move into our area...but my confidence is moderate
that this will occur...believing that it is possible it will shear
out and only clip the extreme SE corner of AZ and impact more of SW
New Mexico. If this does occur, this will likely mean a lower
rainfall potential for our entire CWA. The only caveat is the upper
dynamics ahead of the upper trough along the west coast. The current
forecast pinpoints the best lift Tuesday night in central Arizona
that will result in heavy rain there. If the upper high shifts over,
like I fear...this filed will shift closer to our CWA and thus
increase the threat of heavy rain but this time to the W and NW of
Tucson. In any event, the majority of ensemble members of the SREF
and GEFS still bullish on heavy rain across the forecast area. A
flash flood watch is in effect for all of Southeast Arizona from 5
PM MST Tuesday afternoon until 11 PM MST Wednesday evening.

Impact from this system will wane Thursday morning as it lifts
NE...and especially into the weekend as an upper ridge begins to
establish itself along the west coast. This ridge folds into NW
Arizona this weekend...opening Southeast Arizona up to a NE flow
aloft Sunday and early next week. This would be an active Monsoon
pattern for Tucson.

&&
.AVIATION...Valid through 10/00Z.
Few-sct clouds at 9-11k ft agl west of KTUS and sct-bkn clouds at 7-
9k ft agl from KTUS east thru 09/05z. Clearing skies expected
between 09/05z and 09/17z. Sct-bkn clouds areawide at 6-8k ft agl
aft 09/17z. Isolated to scattered coverage of TSRA/SHRA through
09/04z, mainly east of a KOLS-KTUS-KSOW line. Expect mtn
obscurations and isold MVFR cigs/vsbys. Clouds decreasing and
TSRA/SHRA ending in most areas by 09/06z. Scattered to numerous
TSRA/SHRA will develop on Tuesday across much of southeast Arizona.
Sfc winds generally 10 kts or less outside of TSRA. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Isolated to scattered showers and thunderstorms
will continue through the evening hours tonight. A strong moisture
increase is then expected across the region Tuesday and Wednesday in
conjunction with the remnants of Tropical Storm Javier which will
result in a significant increase in the coverage of showers and
thunderstorms late Tuesday into Thursday...with the potential for
heavy rain during this period. Much higher relative humidities and
cooler daytime temperatures are also expected through this period. A
drying trend, along with warmer temperatures, is then expected over
the upcoming weekend.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from 5 PM MST Tuesday afternoon through 11 PM MST
Wednesday evening for AZZ501>515.

&&

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TUCSON AZ
355 PM MST MON AUG 8 2016

AZZ503-507-513-082330-
UPPER SANTA CRUZ RIVER AND ALTAR VALLEYS INCLUDING
NOGALES-DRAGOON/MULE/HUACHUCA AND SANTA RITA MOUNTAINS INCLUDING
BISBEE/CANELO HILLS/MADERA CANYON-UPPER SAN PEDRO RIVER VALLEY
INCLUDING SIERRA VISTA/BENSON-
355 PM MST MON AUG 8 2016

...SIGNIFICANT WEATHER ADVISORY FOR EASTERN SANTA CRUZ COUNTY UNTIL
430 PM MST...

AT 352 PM MST...DOPPLER RADAR WAS TRACKING AN AREA OF STRONG
THUNDERSTORMS BETWEEN NOGALES AND SONOITA...MOVING NORTHEAST AT
10 TO 15 MPH.

WINDS IN EXCESS OF 45 MPH WILL BE POSSIBLE WITH THESE STORMS ALONG
WITH HEAVY RAIN AND SMALL HAIL.

LOCATIONS IMPACTED INCLUDE...
RIO RICO...PATAGONIA...PATAGONIA LAKE...KINO SPRINGS...
ELGIN AND SONOITA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

HEAVY RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD TO
LOCALIZED FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

&&

LAT...LON 3142 11095 3165 11079 3168 11048 3133 11066
      3133 11084
TIME...MOT...LOC 2252Z 222DEG 17KT 3148 11074

MEYER