WunderBlog Archive » Category 6™
Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.Hybrid coastal storm pounds Southeast coast
A powerful coastal storm centered about 300 miles east of the Georgia coast continues to bring coastal flooding and significant beach erosion from North Carolina to southern Florida. Flood waters driven ashore by winds approaching tropical storm force closed the only road connecting North Carolina's Outer Banks to the mainland on Monday. The water over U.S. 12 just north of Rodanthe cut off a Warner Brothers movie crew filming "Nights in Rodanthe," which stars Richard Gere and Diane Lane. A lifeguard office and garage slid into the ocean at Jupiter Inlet, Florida, and about 100 feet of coastal road were underwater at 1:30 am Tuesday. A coastal flood warning remains in effect for much of the North Carolina coast, where a storm surge of 3-5 feet is expected today. High surf advisories are posted for the entire coast from Maryland to Miami. Winds of minimal tropical storm force (35 knots, or 39 mph) are occurring over a large stretch of ocean surrounding the storm, according to the latest QuikSCAT satellite wind estimates. The South Carolina buoy 41004 had 15 foot seas and sustained winds of 39 mph at 9am EDT this morning.
Figure 1. Model tracks for the Southeast coastal storm, now dubbed "Invest 90L" by NHC.
Figure 1. Visible satellite image of the May 8, 2007 coastal storm.
The coastal low moved over the core of the Gulf Stream (dark orange colors of Figure 3) last night, the warm waters it encountered helped intensify the storm to a central pressure of 1000 mb--which was not forecasted well by the computer models. The low is now a hybrid between a cold-cored Nor'easter and a warm-cored tropical storm, but does not have the characteristics needed to be called a subtropical storm. A subtropical storm has much heavier rains and more organized thunderstorm activity, which typically form a solid band of rainfall 100 miles or more from the center. Today's storm shows no evidence of bands of precipitation forming; the thunderstorm activity is disorganized. If a major organized band of thunderstorms does develop over the next day or two, the NHC could designate this storm as Subtropical Storm Andrea. I am not expecting that to happen, given the marginal SSTs (24-26 C), and significant amount of dry continental air surrounding the storm.
Figure 3. Sea Surface Temperatures on May 7, 2007, as measured by the AVHRR satellite. The dark orange colors mark the position of the Gulf Stream current. Image credit: Ocean Remote Sensing Group, Johns Hopkins university Applied Physics Laboratory.
Cyclone Phase Space diagrams available at the Florida State University web site maintained by Dr. Bob Hart show that the storm has neither a cold nor a warm core, but is a hybrid. The model forecasts call for the storm to remain in this hybrid state until it makes landfall by Thursday morning, somewhere between the Georgia and South Carolina coasts. The storm should gradually decrease in strength, and winds have already dropped considerably from yesterday. Unfortunately, the storm has not acquired enough tropical moisture to be a big rain maker, and its winds are serving to fan fires in southern Georgia and northern Florida. I expect the storm will bring 1-2 inches of rain to South Carolina on Thursday, and lesser amounts to Georgia and northern Florida.
NHC issued this special advisory this afternoon:
SPECIAL TROPICAL DISTURBANCE STATEMENT
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
400 PM EDT TUE MAY 8 2007
A NON-TROPICAL LOW PRESSURE SYSTEM...CENTERED ABOUT 200 MILES SOUTHEAST OF THE GEORGIA AND SOUTH CAROLINA COASTS...HAS BEEN MOVING SLOWLY WESTWARD AT 5 TO 10 MPH. THE LOW IS PRODUCING GALE-FORCE WINDS NEAR THE COASTS OF NORTH CAROLINA...SOUTH CAROLINA...AND GEORGIA. THIS SYSTEM HAS CHANGED LITTLE SINCE THIS MORNING...AND NO SIGNIFICANT STRENGTHENING IS EXPECTED. THE LOW IS BEING MONITORED FOR SIGNS OF TROPICAL OR SUBTROPICAL CYCLONE DEVELOPMENT...AND AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT WILL BE AVAILABLE TO INVESTIGATE THE SYSTEM TOMORROW MORNING...IF
NECESSARY.
INTERESTS ALONG THE COAST OF THE SOUTHEASTERN UNITED STATES SHOULD MONITOR PRODUCTS ISSUED BY LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICES.
Severe weather in the Plains finally abates
The severe storm action finally quieted down yesterday in the Midwest, where no tornadoes were reported for the first time since Thursday. The severe weather action should stay at a slow simmer through Thursday over the Plains; the Storm Prediction Center (SPC) has portions of the region under its "Slight Risk" area for severe weather. Flooding continues to be a major concern over most of eastern Kansas, plus large portions of Oklahoma, Missouri, and Iowa. Although the heaviest rains are now over, river levels are still expected to rise in many regions through Thursday.
Global tropical cyclone record set
Today marks the 31st straight day without a tropical cyclone anywhere in the world, breaking the record for the longest such streak on record. Margie Kieper's View From the Surface blog has more details on this unusual event.
I'll have an update on Wednesday morning.
Jeff Masters
Figure 1. Model tracks for the Southeast coastal storm, now dubbed "Invest 90L" by NHC.
Figure 1. Visible satellite image of the May 8, 2007 coastal storm.
The coastal low moved over the core of the Gulf Stream (dark orange colors of Figure 3) last night, the warm waters it encountered helped intensify the storm to a central pressure of 1000 mb--which was not forecasted well by the computer models. The low is now a hybrid between a cold-cored Nor'easter and a warm-cored tropical storm, but does not have the characteristics needed to be called a subtropical storm. A subtropical storm has much heavier rains and more organized thunderstorm activity, which typically form a solid band of rainfall 100 miles or more from the center. Today's storm shows no evidence of bands of precipitation forming; the thunderstorm activity is disorganized. If a major organized band of thunderstorms does develop over the next day or two, the NHC could designate this storm as Subtropical Storm Andrea. I am not expecting that to happen, given the marginal SSTs (24-26 C), and significant amount of dry continental air surrounding the storm.
Figure 3. Sea Surface Temperatures on May 7, 2007, as measured by the AVHRR satellite. The dark orange colors mark the position of the Gulf Stream current. Image credit: Ocean Remote Sensing Group, Johns Hopkins university Applied Physics Laboratory.
Cyclone Phase Space diagrams available at the Florida State University web site maintained by Dr. Bob Hart show that the storm has neither a cold nor a warm core, but is a hybrid. The model forecasts call for the storm to remain in this hybrid state until it makes landfall by Thursday morning, somewhere between the Georgia and South Carolina coasts. The storm should gradually decrease in strength, and winds have already dropped considerably from yesterday. Unfortunately, the storm has not acquired enough tropical moisture to be a big rain maker, and its winds are serving to fan fires in southern Georgia and northern Florida. I expect the storm will bring 1-2 inches of rain to South Carolina on Thursday, and lesser amounts to Georgia and northern Florida.
NHC issued this special advisory this afternoon:
SPECIAL TROPICAL DISTURBANCE STATEMENT
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
400 PM EDT TUE MAY 8 2007
A NON-TROPICAL LOW PRESSURE SYSTEM...CENTERED ABOUT 200 MILES SOUTHEAST OF THE GEORGIA AND SOUTH CAROLINA COASTS...HAS BEEN MOVING SLOWLY WESTWARD AT 5 TO 10 MPH. THE LOW IS PRODUCING GALE-FORCE WINDS NEAR THE COASTS OF NORTH CAROLINA...SOUTH CAROLINA...AND GEORGIA. THIS SYSTEM HAS CHANGED LITTLE SINCE THIS MORNING...AND NO SIGNIFICANT STRENGTHENING IS EXPECTED. THE LOW IS BEING MONITORED FOR SIGNS OF TROPICAL OR SUBTROPICAL CYCLONE DEVELOPMENT...AND AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT WILL BE AVAILABLE TO INVESTIGATE THE SYSTEM TOMORROW MORNING...IF
NECESSARY.
INTERESTS ALONG THE COAST OF THE SOUTHEASTERN UNITED STATES SHOULD MONITOR PRODUCTS ISSUED BY LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICES.
Severe weather in the Plains finally abates
The severe storm action finally quieted down yesterday in the Midwest, where no tornadoes were reported for the first time since Thursday. The severe weather action should stay at a slow simmer through Thursday over the Plains; the Storm Prediction Center (SPC) has portions of the region under its "Slight Risk" area for severe weather. Flooding continues to be a major concern over most of eastern Kansas, plus large portions of Oklahoma, Missouri, and Iowa. Although the heaviest rains are now over, river levels are still expected to rise in many regions through Thursday.
Global tropical cyclone record set
Today marks the 31st straight day without a tropical cyclone anywhere in the world, breaking the record for the longest such streak on record. Margie Kieper's View From the Surface blog has more details on this unusual event.
I'll have an update on Wednesday morning.
Jeff Masters
Wildfires in Florida
Flooding
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