DeZert News Advisory***Sunday, September 20, 2015***Desert Weather

LIVE! From the Big Bad DeZert

UPDATE! Tuesday, 2 AM

FLASH FLOOD WATCH DROPPED

CURRENT REPORTING STATIONS 2:00 AM

BIG BAD DESERT USA
   
 CITY           SKY/WX    TMP DP  RH WIND       PRES   
 IMPERIAL AP    CLOUDY    82  69  64 SE5       29.74S                  
 EL CENTRO NAS  MOCLDY    79  68  69 SE7       29.76S                  
 YUMA AZ        PTCLDY    81  69  67 SE9       29.78S                  
                 
 
2 AM; 9-22-2015: Watch Dropped

MOST SOUTHERN CALIFORNIA REPORTING STATIONS ARE 

REFLECTING VERY WARM OVERNIGHT TEMPERATURES AND

CLOUDY SKIES.

SOUTHERN DESERT REPORTING STATIONS ARE REPORTING

WINDS OUT OF THE SOUTHEAST TO TEN KNOTS.

RAPID CLEARING IS EXPECTED TODAY AND WEDNESDAY.

END OF REPORTING STATION POSTS IN THIS NEWS COMP. 

12:30 PM 9-21: Watch Continues

FLASH FLOOD WATCH ENDS AT 11PM PACIFIC

TIME...

THIS WEATHER EVENT SHOULD BREAK FULLY,

ON WEDNESDAY, WITH RAPID DRYING AND

CLEARING 

"CONVECTION AHEAD OF THE LOW LEVEL CENTER 

HAS BEEN RATHER CONSOLIDATED AND ROBUST EARLY 

THIS MORNING NEAR THE BAJA BORDER...

THE LOW PRESSURE AND A WEAK TROPICAL WAVE

IS MOVING THE MOISTURE NORTHWEST... 

NORTHWEST MOVING RAINFALL IS DIMINISHING

AS THE DAY PROGRESSES...

TONIGHT, RAINFALL COULD EXPAND ON THE 

DROPPING AIR TEMPERATURES.

RAINFALL SOUTH AND WEST OF MEXICALI,

IN BAJA MEXICO HAS BEEN HEAVY, MID-DAY.

IN ARIZONA AND NEW MEXICO, THE TROPICAL 

ENVIRONMENT REPRESENTED THERE WILL
BRING A DRAMATIC CHANGE TO PRECIPITABLE WATER VALUES

ABOVE SIX INCHES OF RAIN...AND GIVEN THE 

TROPICAL AIRMASS...WOULD NOT BE SURPRISED TO SEE

THESE TOTALS IN ARIZONA AND NEW MEXICO. 

AMOUNTS OF ONE TO TWO INCHES ARE POSSIBLE IN 

THE RACE COURSE AREA (IMPERIAL VALLEY), TODAY. 

ALONG SOUTH AND EAST FACING TERRAIN ARE IN 

THE GREATEST RAIN EXPOSURE AREAS...

ESPECIALLY IF THE LOW LEVEL CIRCULATION REMAINS INTACT
AND SLOWS AS IT INTERACTS WITH THE MOUNTAINS. 

THAT WOULD BE IN A WORSE CASE SCENARIO...

BUT IS WORTH CONSIDERING IN PLANNING.
REGARDLESS OF EVENTUAL TOTALS...RAIN RATES 

EXCEEDING 2 INCHES PER HOUR IN THE DEPRESSION PATH,

DURING THE HEIGHT OF THE EVENT WILL OVERWHELM 

THE FLASH FLOOD GUIDANCE VALUES IN THIS REGION...

SUGGESTING POTENTIAL FOR
SIGNIFICANT IMPACTS." 

1 AM Monday Morning: Watch continues overnight into September 21:

For Southern California: "THE CORE OF THE UPPER
LOW WAS ACTIVE WITH POCKETS OF CONVECTION

BENEATH IT THIS MORNING...AND SHOULD

CONTINUE TO PRODUCE CONVECTION AS IT

APPROACHES SOUTHERN CALIFORNIA MONDAY

NIGHT. EASTERLY MID LEVEL WINDS WILL

CARRY AIR WITH PW VALUES APPROACHING

1.25 TO 1.50 INCHES INTO THE L.A. BASIN

AND NEAR SAN DIEGO...

SO LOCALLY HEAVY DOWNPOURS DO APPEAR

POSSIBLE IN MORE DIRECT ASSOCIATION

WITH THE UPPER LOW RATHER THAN THE

TROPICAL DEPRESSION.(SIXTEEN-E)"

Southern California rain deluge threat moves from the tropical depression, which now is moving farther east, to the steering desert low pressure, making Los Angeles and San Diego heavy downpours possible today, Monday, Sept 21.

 Race Event Location thru Tuesday Evening

"MAXIMUM RAINFALL AMOUNTS SHOULD BE REALIZED

 THERE (Imperial County) WITH WIDESPREAD

 2 INCH AMOUNTS LIKELY AND ISOLATED 
  AMOUNTS OF 3 TO 4 INCHES POSSIBLE.

 A FLASH FLOOD WATCH WAS ISSUED FOR

 THE MOUNTAINS AND EASTERN DESERTS

 DUE TO MODERATE CONFIDENCE IN WIDESPREAD

 FLASH FLOODING POSSIBILITIES FOR MONDAY

 AFTERNOON THROUGH TUESDAY." 

5 AM Sunday Sept. 20: The Baja Weather Service reports today, the planned Imperial Valley race could be impacted by a tropical depression currently located west of Baja South this morning. Race activities could be impacted by the adverse impacts of heavy rainfall in the region, this week. 

Rainfall generated from the system and potential flash flooding from the the depression is expected to move north into Southern California Monday, September 21 and Tuesday, September 22. Current forecast models place the center of circulation of the tropical disturbance, driving through Imperial Valley during the week, full of scheduled desert off-road racing festivities. 

The National Weather Service reported today: "Deep atmospheric moisture associated with this disturbance is expected to produce heavy rains across portions of the Baja California peninsula and northwestern Mexico today, and over portions of southern California and Arizona on Monday and Tuesday. These rains could produce life-threatening flash floods and mud slides, especially in mountainous areas".