U.S. Air Force Reserve and NOAA Hurricane Hunter aircraft found sufficiently strong winds and just enough organization for the National Hurricane Center to deem this a tropical storm Thursday morning.
Hurricane watches are in effect in southern Louisiana from the mouth of the Mississippi River westward to Cameron, Louisiana. This means hurricane conditions are possible in the area within the next 48 hours.
A tropical storm warning has now been issued for a portion of the southern Louisiana coast from the mouth of the Pearl River at the border with Mississippi to Morgan City, Louisiana.
Tropical storm watches have now been extended to cover the Mississippi Gulf Coast, in addition to a section of southeastern Louisiana from the mouth of the Mississippi River northward to the mouth of the Pearl River at the border with Mississippi. This watch includes the New Orleans metro area and Lake Pontchartrain. This means tropical storm conditions are possible in the area within the next 48 hours.
A storm-surge warning has now been issued for a portion of the southeast and south-central Louisiana coast from Shell Beach along the shore of Lake Borgne to the mouth of the Atchafalaya River. A warning means there is a danger of life-threatening inundation from rising water moving inland from the coast within the next 36 hours.
Storm-surge watches are in effect from Shell Beach, Louisiana, to the Mississippi/Alabama border and also from the mouth of the Atchafalaya River to Intracoastal City, Louisiana. It does not include Lake Pontchartrain. A watch means life-threatening inundation is possible within the area, generally within 48 hours.
Barry will be steered westward or northwestward through the northern Gulf of Mexico in the direction of Louisiana or Mississippi, then drawn inland this weekend into the lower Mississippi Valley through a gap between a high-pressure systems in the Rockies and an extension of the Bermuda high over the Bahamas and the Florida Peninsula.
For now, it looks like landfall should occur either late Friday night or early Saturday. A landfall would occur earlier/later if the center tracks along the right/left side of the forecast cone below.
Barry may be able to gain enough strength to become a hurricane prior to landfall.
Residents along the northern Gulf Coast should monitor the forecast closely knowing that conditions could change, and make sure your preparedness kit is ready to go and heed all evacuation orders from local officials.
Potential Impacts
Rainfall Flooding
Regardless of whether Barry is a tropical storm or hurricane, a major threat of heavy rain and flash flooding is in play into early next week somewhere near and inland from the Gulf Coast.
How much rain falls depends on how fast Barry moves and its exact track, rather than its intensity.
Typically, these types of tropical cyclones produce their heaviest rain along and to the east of their tracks. This suggests heavy rain is possible in parts of Louisiana, Mississippi, Arkansas, Alabama and the western Florida Panhandle.
At least locally heavy rain is likely to persist over parts of the South well after the center moves ashore and may persist into early next week.
For now, the NHC suggests 10 to 15 inches of additional rain could fall through early next week, with isolated totals up to 20 inches in parts of the Lower Mississippi Valley.
Flash flood watches have been posted along portions of the northern Gulf Coast from the far western Florida Panhandle into Louisiana.
NOAA's Weather Prediction Center has also issued a high risk of excessive rainfall for portions of southern Louisiana, including the New Orleans metro area for Saturday. About 40 percent of all U.S. flood deaths and 90 percent of all flood-related damage occurs in and near high risk areas.
Storm-Surge Flooding
Increasing onshore flow is expected to produce coastal flooding at high tide as soon as Thursday along the northern Gulf Coast.
In general, peak water rise from storm surge will occur along and to the east of Barry's track near landfall, anytime from late Friday night into Saturday.
Onshore winds should persist for some time Saturday, perhaps into Sunday to the east of Barry's center, even as Barry is inland, continuing coastal flooding in some spots.
The inundation forecast below from the NHC should be thought of as peak water levels above ground if storm surge occurs at high tide. The times of normal high tide are generally near or just after dawn along the Louisiana and Mississippi coasts. At Shell Beach, Louisiana, just east of New Orleans on the south shore of Lake Borgne, high tides occur in late morning each day through Sunday.
This surge flooding will only aggravate rainfall flooding, not allowing swollen bayous and rivers to drain to the Gulf.
These onshore winds will also produce dangerous, life-threatening rip currents along parts of the northern and eastern Gulf Coast. Gulf waters were closed at both Orange Beach, Alabama, and Panama City Beach, Florida, Thursday, due to the rip current danger.
Winds
Hurricane-force winds (74-plus mph) are possible in the hurricane watch area in southern Louisiana by Friday night, with tropical-storm-force winds (39-plus mph) possible by early Friday.
Tropical-storm-force winds are expected to arrive in the tropical storm warning area in southeastern Louisiana Friday. Coupled with increasing coastal flooding, that may make final preparations difficult.
Tornadoes
A couple of tornadoes may develop across parts of southeastern Louisiana, southern Mississippi and southwestern Alabama, through Friday or Saturday.