Rain Rate Question

[Constructionwx]

Hey RP...here are a few rainfall stats for my location in Douglasville..

4.54" - rainfall between 10 p.m. and 4 a.m. last night (roads closed this morning everywhere in town).

11.28" - rainfall since June 1st (normal precip for 6/1-17 is only about 2.00")

21.07" - rainfall since May 1st (normal is 5.70")

35.80" - rainfall total in 2003 (normal is 25.2")

64.81" - rainfall at my location since September 01, 2002....the past 9 1/2 months. Normal for the Sept to mid-June period is around 38.8"; or +26" above normal)

If any tropical storms/ hurricanes track anywhere near metro Atlanta this season, we are now primed for record flooding...as bad as Alberto (1994) or worse

Perry

I'm going to go through my stuff since Sept. 02. It seems like you have been blessed with a little more rain than me.

I missed the 94' flooding here. I was still living in West Palm Beach. But I can vouch for the flooding threat now. The ground is soooo saturated. I thought that I would need a backhoe today in order to dig a long shallow trench. lol, the backhoe was stuck in the mud in someones backyard. So, I decided to used one of those little Kubota(sp?) tractors. The same tractor that would barely scrape the surface 12 months ago. Today, it cut the soil like butter!!

[Constructionwx]

Help a brother out. What does PWAT stand for?
TIA,
Richard

These airmasses that become locked over the Southeast can produce tremendous rainfalls in short periods of time ... especially when PWAT climbs over 2" ... look at the thread (South Carolina ... big rainfall problems) for doppler radar estimates since June 16th (Monday-Tuesday) - some locations in Berkeley County picked up 5" of rain in one hour ...

Some of the rainfall rates have I'm sure have had 10" of rainfall in one hour either yesterday or today from the heaviest convection (and based on a 62 DBZ reflectivity I saw from a storm yesterday morning in Berkeley County which produced the 5" in one hour) ... Ironic really, that in terms of longetivy rainfall situations such as a landfall tropical system, rainfall rates are heavy (and span longer timeframes), but intense (and usually pulse) thunderstorms with a very high PWAT atmosphere to work with produces the highest short-term rainfall rates ... (in which sometimes occurs after a tropical systems' demise - case in point, Tropical Storm Hermine in my location - the remnants of the decayed system sparked off thunderstorms - one which sat in my location for about 3 hours produced 8"-10" of rainfall ... I recorded 9.55" of rain in 147 minutes).

Aslkahuna made a great post in this thread involving the records, which again ironically being Holt, MO holding the record for most rainfall in an hour or less in the world (considering some of the rainiest locations in the world) ...

[Stormsfury]

PWAT stands for Precipitable WATer ... or simply the amount of moisture available for squeezing out from the atmosphere (in layman's terms) ... sorry I can't give you a better definition ...

The higher the PWAT index, the more moisture that is available.
PWATs less than 1" indicate a drier atmosphere, while atmospheres with over 1.50" are juicy ... anything over 2" indicates a very moisture-laden atmosphere. (Currently what South Carolina is seeing) ...

Hope this helps.

SF

[Stormsfury]

Hey RP...here are a few rainfall stats for my location in Douglasville..

4.54" - rainfall between 10 p.m. and 4 a.m. last night (roads closed this morning everywhere in town).

11.28" - rainfall since June 1st (normal precip for 6/1-17 is only about 2.00")

21.07" - rainfall since May 1st (normal is 5.70")

35.80" - rainfall total in 2003 (normal is 25.2")

64.81" - rainfall at my location since September 01, 2002....the past 9 1/2 months. Normal for the Sept to mid-June period is around 38.8"; or +26" above normal)

If any tropical storms/ hurricanes track anywhere near metro Atlanta this season, we are now primed for record flooding...as bad as Alberto (1994) or worse

Perry

I'm going to go through my stuff since Sept. 02. It seems like you have been blessed with a little more rain than me.

I missed the 94' flooding here. I was still living in West Palm Beach. But I can vouch for the flooding threat now. The ground is soooo saturated. I thought that I would need a backhoe today in order to dig a long shallow trench. lol, the backhoe was stuck in the mud in someones backyard. So, I decided to used one of those little Kubota(sp?) tractors. The same tractor that would barely scrape the surface 12 months ago. Today, it cut the soil like butter!!

So far, this year ... not including today, I've picked up 29.64" for the year of 2003 ... From June of last year, an estimated 45"...which puts me approximately 75" for a 12 month period - or roughly 25" above normal ...

Believe it or not ... Columbia, SC during the 4 year drought from 1998-2002 was over 80" below normal ... It would take more rainfall than I got in a 12 month period to put them back even (even though the drought has been officially over since the end of last year)...

[Constructionwx]

Stormsfury,

Would a PWAT of ~ 1" in the winter time still be considered dry?

[Stormsfury]

Stormsfury,

Would a PWAT of ~ 1" in the winter time still be considered dry?

Yep - to a fault - earlier this winter, though, CHS had a PWAT index of 0.10" - that's extrememly dry!... the next day, moisture recovery put the PWAT table around 1.32" and heavy rainfall was the result ...

Even PWAT's around 1" can still produce thunderstorms in the summertime ... in which a lot of times, you would see that in the Western states ... (lot of times, "dry" thunderstorms)