Thursday, August 8, 2013

A Tale Of Two Halves



This summer has been one of persistence across the U.S. in the general weather pattern.  The West has been too dry and the East too wet.  Severe to exceptional drought covers much of the western half of the country, while flooding and downpours have drenched the Southeast and Mid-Atlantic.  Some areas have seen relief from the devastating drought of last year and it has gotten worse for others.

The U.S. Drought Monitor for August 6, 2013.  This shows the areal extent of drought across the U.S. at this point in time.  Click on the image for a larger view.  Image Credit: NOAA/USDA.

The worst of the drought continues to be in the High Plains, but it is getting worse over much of the Southwest.  This has already led to an above normal wildfire season in the West.


June and July rainfall across the U.S. in 2013.  Wet in the East and dry in the West.  Click on the image for a larger view.  Image Credit: Climate Central.

In the top graphic above, you will see the accumulated rainfall from the last 60 days across the continental U.S. based on data from the NOAA/NWS Advanced Hydrologic Prediction Service.  The Pacific Northwest and northern California, in particular, were unusually dry. Summer is generally the driest part of the year for Seattle, but this July has been extreme with only a trace of rain recorded for the entire month. During this dry stretch, wildfires have been growing in number and size across the Northwest. Meanwhile, the recent heavy rain has provided some relief to drought-stricken areas across the Southwest, Texas, and Oklahoma, but not enough to bring the region out of the drought that has devastated the area since last year.

July rainfall across the U.S. in 2013.  The map shows the percent of normal rainfall.  Click on the image for a larger view.  Image Credit: Climate Central.

Farther east, it's a completely different story. Rounds of record breaking rain have soaked the Southeast. Both Ashville and Greenville-Spartanburg, NC have recorded their wettest July on record. This comes on the heels of Macon, GA notching its wettest June ever. It’s not just monthly rainfall records that are falling, though. Farther north in Philadelphia, a whopping 8.02" of rain fell on July 28th with 7.35" falling in just four hours - an all-time daily record and a downpour you'd expect to come along one in ever thousand years. That made this the wettest July on record for Philly, following their wettest June ever.

It has been exceptionally wet for South Carolina.  Above normal rainfall has been seen everywhere over the past 60 days, but it has been least along the coast and most in the mountains.

The percent of normal rainfall across South Carolina for the last 60 days ending on August 8, 2013.  Click on the image for a larger view.  Image Credit: NOAA/AHPS.

Columbia saw the 5th (correction: 15th) wettest June on record while it was the 3rd wettest June on record for South Carolina.  July proved to be wetter in total rainfall, but it was only the 6th wettest July on record for Columbia.  August would have to top 11.9 inches of rain for this to be the wettest summer on record in Columbia.  The record for the month of August is 16.72 in 1949, so this is possible.  July and August are the two wettest months of the year.

Rainfall varied greatly across the Midlands in July.  The National Weather Service Forecast Office in Columbia collected many of the reports.  Here are some of the rainfall totals from the COCORAHS, NWS Coop Observers, and the Richland County Mesonet.

COCORAHS:

SC-KR-14 (LUGOFF 2.2 NNW)......17.89 INCHES
SC-LX-5  (LEXINGTON 1.6 WNW)...15.44 INCHES
SC-OR-5  (HOLLY HILL 0.4 N)....15.31 INCHES
SC-OR-22 (SANTEE 6.9 WSW)......14.60 INCHES
SC-CD-9  (MANNING 8.2 SE)......14.13 INCHES
SC-OR-14 (CORDOVA 3.2 SSE).....13.75 INCHES
SC-LX-64 (CAYCE 1.2.SW)........13.57 INCHES
SC-SM-10 (SUMTER 0.3 ENE)......13.41 INCHES
SC-LX-57 (W. COLUMBIA 1.2 ESE).13.55 INCHES
SC-RC-42 (COLUMBIA 3.1 E)......13.23 INCHES
SC-SM-1  (SUMTER 1.3 SE).......12.80 INCHES
SC-AK-39 (N. AUGUSTA 1.5 WSW)..12.56 INCHES

NOTE...YOU CAN BECOME A COCORAHS OBSERVER AND MEASURE RAINFALL IN YOUR BACKYARD...WORK OR SCHOOL. THE WEBSITE IS WWW.COCORAHS.ORG


NWS COOPERATIVE OBSERVERS:

SUMTER (SMRS1).................15.63 INCHES
CLARKS HILL (CHDS1)............13.95 INCHES
UNIV. SOUTH CAROLINA (USCS1)...13.58 INCHES
LUGOFF 2 NE (LUGS1)............13.33 INCHES
MANNING (MANS1)................13.18 INCHES
BAMBERG (BAMS1)................12.96 INCHES
BARNWELL 5 ENE (BNLS1).........11.49 INCHES
JOHNSTON 4 SW (JOHS1)..........11.45 INCHES
CHERAW WATER PLANT (CEWS1).....10.30 INCHES
APPLING 2 NW (APLG1)............9.96 INCHES


RICHLAND COUNTY MESONET:

GILLS CREEK....................16.32 INCHES
DETENTION CENTER...............14.60 INCHES
GADSDEN........................12.08 INCHES
PINE VIEW/GARNERS FERRY........11.76 INCHES
DOWNTOWN COLUMBIA..............11.60 INCHES

Heavy rain and severe dry spells are some of the weather extremes that come along with climate change.  Sometimes, like this year, they can exist across the country at the same time.  The contrast has been quite noticeable in South Carolina, because last year was so dry and this year so wet.  What is most disturbing is that the extremes of precipitation are becoming more extreme.

Climate Central has put together a nice video explaining how climate change is affecting heavy rainfall.