Extended Heavy Rain Event Approaching - Special Weather Statement Issued

Beginning on the 25th I've been talking about a very wet period that was taking shape beginning tomorrow. A very unusual summer weather pattern is beginning to unfold, and Georgia is going to get right in the middle of it.

First, here is an excerpt from this mornings Area Forecast Discussion (AFD) from the Atlanta NWS office:

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...

HIGH AMPLITUDE UPPER LEVEL PATTERN IN PLACE ACROSS THE CONUS
THROUGH THE LONG TERM PERIOD. 
BY TUESDAY... SLOWLY RETROGRADING UPPER TROUGH PROGGED BY MED RANGE MODELS TO BE LOCATED ALONG MS VALLEY SANDWICHED BETWEEN TWO LARGE UPPER HIGHS... ONE OVER WRN STATES AND THE OTHER JUST OFF THE EAST COAST TUESDAY. THIS IS NOT A GOOD PATTERN TO BE IN WITH POTENTIAL FOR SIGNIFICANT HEAVY RAIN EVENTS OVER 2 TO 3 DAYS... MAINLY WED AND THURS. 

PLUME OF RICH MONSOONAL LIKE MOISTURE SPREADS WEST INTO THE REST OF THE STATE ON WED AND SPIKES ON THURS /4TH OF JULY/ WITH PW (PW is Precipitable Water) VALUES OF 2 TO 2.4 INCHES. PW OF 2.2 INCHES IS ABOVE THE 99TH PERCENTILE AND NEAR ALL-TIME RECORD VALUE BASED ON 60 YEAR CLIMATOLOGY OF FFC/AHN (Atlanta and Athens) RAWINSONDE DATA. 
WILL LIKELY ISSUE SPS AND SPECIAL GRAPHIC IN ADDITION TO BRIEF HEADS UP IN LONG TERM PORTION OF HWO TO HIGHLIGHT HEAVY RAIN... FLOODING AND LIGHTNING THREATS.

We'll be keeping an eye on the Flash Flood Guidance maps as the time gets closer. These maps give you an idea of how much rain it would take over a given period of time, before flash flooding becomes an issue. If we get two or three days of heavy rainfall on top of the already soggy soils we have, excessive runoff will lead to flash flooding. If you live in a low lying area that is prone to flooding, I would go ahead and prepare in advance.

I also have a page that displays many of the east metro river and creek gauges that comes in very handy during heavy rain events. If you don't see a river or creek on this page, and there is one near your location, let me know and I'll try to get it added.  

While I was typing this, the Atlanta NWS office just issued a Special Weather Statement:

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
551 AM EDT SUN JUN 30 2013

...PROLONGED PERIOD OF STRONG THUNDERSTORMS AND VERY HEAVY RAINFALL LIKELY TUESDAY THROUGH FRIDAY...

...FOURTH OF JULY OUTDOOR ACTIVITIES WILL LIKELY BE IMPACTED...

A STAGNANT... YET VIGOROUS UPPER LEVEL PATTERN IS BRINGING
TOGETHER THE INGREDIENTS FOR A PROLONGED PERIOD OF THUNDERSTORMS AND VERY HEAVY RAINFALL ACROSS NORTH AND CENTRAL GEORGIA FOR MUCH OF THIS WEEK. WARM SOUTHERLY FLOW... RICH IN MOISTURE... IS DEVELOPING ACROSS FLORIDA AND THE CAROLINAS. AS HIGH PRESSURE ALOFT OVER THE WESTERN ATLANTIC AND AN UPPER LEVEL TROUGH OF LOW PRESSURE OVER THE MISSISSIPPI VALLEY MOVE WEST... THIS PLUME OF RICH MOISTURE WILL SHIFT WEST OVER GEORGIA AND REMAIN IN PLACE TUESDAY THROUGH FRIDAY. RAINFALL AMOUNTS TUESDAY THROUGH FRIDAY COULD RANGE FROM 2 TO 4 INCHES WITH LOCAL AMOUNTS AROUND 5 INCHES POSSIBLE. FLOODING MAY ALSO OCCUR IF VERY HEAVY RAIN REPEATEDLY FALLS OVER THE SAME AREAS. IN ADDITION... SOME OF THESE STORMS COULD BE STRONG TO SEVERE WITH WIND GUSTS TO 60 MPH... HAIL AND FREQUENT CLOUD TO GROUND LIGHTNING.

PERSONS PLANNING OUTDOOR ACTIVITIES THIS WEEK... INCLUDING THOSE ON THE FOURTH OF JULY... SHOULD CONTINUE TO MONITOR THE LATEST FORECASTS AND BEGIN MAKING CONTINGENCY PLANS IN CASE HAZARDOUS WEATHER THREATENS.

And this from Steven Nelson, one of the lead forecasters from the Atlanta NWS office:

BY 12Z SUN...STORM TOTAL QPF FROM 00Z GFS/ECMWF INDICATE 2 TO 5 INCHES OF RAIN BUT PRIOR EXPERIENCE SAYS WILL SEE MUCH MORE THAN THAT ON SMALLER MESO ALPHA SCALE. DO NOT HAVE A GOOD FEELING ABOUT THIS. 
SNELSON

More on this later...

Please remember, whenever you need weather information, please visit us at the new and improved DaculaWeather.com. You can also get the latest weather information by following us on Twitter, Facebook, and here on Dacula Patch! DaculaWeather.com... Your Window to the Weather