Beryl a little stronger, closes in on Southeast U.S. coast
The beach-going weather this Memorial Day weekend will deteriorate rapidly this afternoon along the Southeast U.S. coast near the Florida/Georgia border, where Subtropical Storm Beryl is steadily closing in. A hurricane hunter aircraft found top surface winds near 60 mph in heavy thunderstorms to the northeast of Beryl's center at 9:15 am EDT this morning; top winds in the region to the southwest of the center were a little weaker, near 55 mph. This region is now approaching the coast of northern Florida. Winds at the Buoy 41012, 46 miles ENE of St. Augustine and to the southeast of Beryl's center, hit 38 mph gusting to 49 mph, at 11 am EDT this morning. Wave heights at the buoy were 12 feet, and Beryl is driving heavy surf that is generating dangerous rip currents along a large section of the Southeast U.S. coast. On Saturday, at least 32 people were rescued by lifeguards at Tybee Island, Georgia due to strong rip currents generated by Beryl's crashing surf.
Figure 1. True-color MODIS satellite image of Beryl taken at 12:20 pm EDT May 26, 2012 by NASA's Aqua satellite. At the time, Beryl was a subtropical storm with winds of 45 mph.
Figure 2. Morning radar image from the long-range radar out of Jacksonville, FL.
Forecast for Beryl
Beryl is still a subtropical storm, as evidenced by its large, cloud-free center, but the storm is steadily building a large amount of heavy thunderstorms near the center this morning, as the storm traverses the core of the Gulf Stream. The warm 27 - 28°C (81 - 83°F) waters of the Gulf Stream are helping warm and moisten the atmosphere near Beryl's core, and it is possible that Beryl will become a tropical storm before landfall late Sunday night. As I explain in my Subtropical Storm Tutorial, the fact that the storm has not been able to generate a tight inner core with heavy thunderstorms near the center will limit its intensification potential, and we need not be concerned about rapid intensification of Beryl while it is still subtropical.The clockwise flow of air around an extremely intense ridge of high pressure that is bringing record heat to the Midwest this weekend is currently driving Beryl to the west. As Beryl approaches the coast tonight, the storm will move off of the warmest Gulf Stream waters into waters that are cooler (25°, 77°F), and with lower total heat content. A portion of the storm's circulation will also be over land, and these two factors will limit the storm's potential to strengthen. Beryl is also struggling against a large amount of dry that surrounds the storm, due to the presence of an upper-level trough of low pressure. The 11 am Sunday wind probability advisory from NHC gave Beryl just an 6% chance of becoming a hurricane before landfall. Flooding due to heavy rains is probably not a huge concern with this storm, particularly since the Southeast U.S. coast is under moderate to extreme drought. The 3 - 6 inches of rain expected from Beryl will not be enough to bust the drought, since the Southeast U.S. is generally suffering a rainfall deficit of 9 - 12 inches (Figure 4.) Heavy rains from Beryl will begin affecting coastal Georgia and Northern Florida near 3 pm Sunday.
Figure 3. Predicted rainfall from Beryl, as taken from the 06 UTC May 27, 2012 run of the HWRF model. A large area of 4 - 8 inches of rain (dark green colors) is predicted for the drought-stricken areas of Northern Florida and Southern Georgia. Image credit: Morris Bender, NOAA/GFDL.
Figure 4. Much of the Southeast U.S. needs 9 - 12 inches of rain (red colors) to bust the current drought. A drought is defined as "busted" when the Palmer Drought Severity Index (PDSI) goes higher than -0.5. As seen from the HWRF precipitation forecast in Figure 3, most of the drought relief from Beryl will occur near the coast, and the most needy areas (purple colors in Figure 3) are expected to get little rainfall. Image credit: NOAA.
Links to follow
Wundermap for the FL/GA coastal region
Long-range radar out of Jacksonville, FL
Jacksonville, FL live pier cam
Scorching May heat wave hits much of the U.S.; severe weather expected in the Midwest
An exceptionally strong high pressure system anchored over the central U.S. is bringing record-smashing May heat to much of the country this Memorial Day weekend. Dozens of daily high temperature records fell on Saturday, including several all-time records for the month of May. Vichy-Rolla, Missouri hit 98°F, beating its all-time May heat record of 95° set on May 15, 1899. Columbus, Georgia hit 97°F, tying the record hottest May day on record. Saturday's high of 100°F in Tallahassee was the second highest May temperature since record keeping began in 1892. Pensacola's 98°F on Saturday was its second highest May temperature since record keeping began in 1879 (the record May temperature in both cities is 102°F, set on May 27, 1953.) Nashville, Tennessee hit 95°F on Saturday, just 1° shy of their all-time May heat record. That record could fall today, and numerous all-time May heat records will be threatened in the Midwest, Great Lakes, and Tennessee Valley. As is often the case when one portion of the country is experiencing record heat, the other half is seeing unusually cool conditions, due to a large kink in the jet stream. Billings, Montana received 1.3" of snow Saturday, and Great Falls had received 2.3" as of 6 am this morning. The dividing line between the warm conditions in the Eastern U.S. and cool conditions to the west lies over Nebraska and Kansas today, and NOAA's Storm Prediction Center (SPC) has placed portions of these states in their "Moderate Risk" area for severe weather--the second highest level of alert.