The peak of Hurricane Season is coming – whether we like it or not. The peak of the Atlantic hurricane Season is on September 10th, and the Atlantic basin is reflecting that.
Hurricane Dorian is still churning up the east coast of Florida. Tropical Storm Fernand is moving toward Mexico. Newly-minted Tropical Storm Gabrielle is moving northwest from the coast of Africa toward the north Atlantic – out to sea and away from land and there are two other areas of interest to watch, too.
Update on possible development from the NHC
Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Wed Sep 4 2019
For the North Atlantic…Caribbean Sea and the Gulf of Mexico:
The National Hurricane Center is issuing advisories on Hurricane Dorian, located about 100 miles east of the coast of northeast Florida, on Tropical Storm Fernand, located a short distance east of the coast of northeastern Mexico, and on newly formed Tropical Storm Gabrielle, located several hundred miles west-northwest of the Cabo Verde Islands.
1. A small area of low pressure, located just east of Bermuda, is producing disorganized showers and thunderstorms. Some development of this disturbance is possible, and a tropical depression could form during the next couple of days as the disturbance moves northeastward away from Bermuda. Afterward, upper-level winds are forecast to become unfavorable for tropical cyclone formation.
* Formation chance through 48 hours…medium…50 percent.
* Formation chance through 5 days…medium…50 percent.
2. A tropical wave is forecast to emerge later today over the far eastern tropical Atlantic west of Africa. Environmental conditions are forecast to become mostly conducive for development late this week, and this system has the potential to become a tropical depression over the weekend or early next week while it moves westward to west-northwestward.
* Formation chance through 48 hours…low…near 0 percent.
* Formation chance through 5 days…medium…60 percent.
Dorian
Hurricane Dorian Discussion Number 45
NWS National Hurricane Center Miami FL AL052019
1100 AM EDT Wed Sep 04 2019
Satellite imagery indicates that the cloud tops in the eyewall of Dorian have cooled significantly during the past few hours, with the eye becoming better defined in NOAA Doppler radar data. However, just-received reports from an Air Force Reserve Hurricane Hunter aircraft show that the hurricane has changed little in intensity, with maximum winds remaining near 90 kt and the central pressure near 964 mb. The aircraft data show that hurricane-force winds are roughly 50 n mi offshore of the northeastern Florida peninsula, while surface observations show that tropical-storm conditions are affecting portions of the coast of northeastern Florida.
The initial motion is now 335/8. Dorian is moving around the western end of the subtropical ridge, and it should recurve northward and northeastward into the mid-latitude westerlies during the next 24-48 h. This motion should bring the center of Dorian near or over the coast of North Carolina during the 36-48 h period. After that time, the cyclone is forecast to accelerate northeastward into the Atlantic toward the Canadian Maritimes, with a quick northeastward motion continuing for the remainder of the cyclone’s life. The track guidance is very tightly clustered, and the new forecast track, which has only minor changes from the previous forecast, lies in the center of the guidance envelope near the consensus models. It should be noted that the track is close to and almost parallel to the coast of the southeastern United State, and any deviation to the left of the track could bring the center onshore anywhere in the Carolinas.
Dorian is expected to remain in an environment of light to moderate vertical wind shear and warm sea surface temperatures during the next 48 h. As a result, the hurricane is expected to maintain Category 2 intensity as it passes near the southeastern United States coast. After 48 h, increasing shear and dry air entrainment should cause a weakening trend. Extratropical transition should begin near the 72 h time, and the cyclone is forecast to become a hurricane-force extratropical low by 96 h near or over Nova Scotia and Newfoundland.
Since the NHC track prediction continues to take Dorian dangerously close to the southeast U.S. coast, all interests from northeast Florida to the Carolinas should remain vigilant to the possibility of experiencing destructive winds, flooding rains, and life-threatening storm surges from this hurricane.
Key Messages:
1. Life-threatening storm surge and dangerous winds are expected along portions of the Florida east coast and the coasts of Georgia, South Carolina, North Carolina, regardless of the exact track of Dorian’s center. Water levels could rise well in advance of the arrival of strong winds. Residents in these areas should follow advice given by local emergency officials.
2. The risk of dangerous storm surge, wind, and rain impacts along portions of the Virginia coast and the southern Chesapeake Bay continues to increase. Residents in these areas should continue to monitor the progress of Dorian.
3. Flash flooding will become increasingly likely across coastal Georgia into the eastern Carolinas tonight into Friday. There is a high risk of flash flooding over coastal sections of the Carolinas, where significant, life-threatening, flash flooding is expected.
FORECAST POSITIONS AND MAX WINDS
INIT 04/1500Z 29.8N 79.7W 90 KT 105 MPH
12H 05/0000Z 30.8N 80.0W 90 KT 105 MPH
24H 05/1200Z 31.9N 79.8W 85 KT 100 MPH
36H 06/0000Z 33.1N 78.6W 85 KT 100 MPH
48H 06/1200Z 34.8N 76.4W 85 KT 100 MPH
72H 07/1200Z 39.9N 68.2W 75 KT 85 MPH
96H 08/1200Z 47.5N 59.0W 70 KT 80 MPH…POST-TROP/EXTRATROP
120H 09/1200Z 55.0N 46.0W 60 KT 70 MPH…POST-TROP/EXTRATROP
Fernand
Tropical Storm Fernand Discussion Number 6
NWS National Hurricane Center Miami FL AL072019
1000 AM CDT Wed Sep 04 2019
Early morning visible satellite imagery shows that the center of Fernand is farther north than previously estimated. Most of the deep convection has moved inland and is located to the north and west of the center due to easterly shear. Dvorak T-numbers have decreased and the area where earlier scatterometer data showed the strongest winds were located has moved inland, so the initial intensity has been reduced to 40 kt. Little change in strength is predicted before the center moves inland later today. After that, rapid weakening should occur while Fernand moves farther inland tonight, and the system should dissipate over the higher terrain of northeastern Mexico by Thursday.
The initial motion of the system is a somewhat uncertain 295/7 kt. The cyclone should continue on a westward to west-northwestward track to the south of a strong deep-layer ridge located over the south-central United States. The new NHC track forecast has been adjusted north of the previous advisory due to the more northward initial position, but still lies near the middle of the guidance envelope.
The primary threat from this system will be heavy rainfall that could produce flooding and mudslides, especially in the mountainous areas of northeastern Mexico. Radar estimates from the NOAA Doppler weather radar in Brownsville, Texas (KBRO), indicate that 9 to 12 inches of rainfall may have already occurred across portions of these areas.
ORECAST POSITIONS AND MAX WINDS
INIT 04/1500Z 24.2N 97.3W 40 KT 45 MPH
12H 05/0000Z 24.7N 98.9W 30 KT 35 MPH…INLAND
24H 05/1200Z 25.5N 101.0W 20 KT 25 MPH…POST-TROP/REMNT LOW
36H 06/0000Z…DISSIPATED
Gabrielle
Tropical Storm Gabrielle Discussion Number 4
NWS National Hurricane Center Miami FL AL082019
1100 AM AST Wed Sep 04 2019
Gabrielle appears better organized on satellite imagery this morning with the low-level center moving a little more underneath the convection. In addition, a large curved band has become better defined in the northern semicircle. The initial wind speed is increased to 45 kt, which is consistent with a just-received ASCAT-C pass of 40-45 kt.
The initial motion estimate is 320/8. For the next 5 days, Gabrielle is forecast to move generally northwestward toward a break in the Bermuda-Azores high pressure ridge located between 40W-50W longitude. An increase in forward speed in a few days is expected due to the gradient between an upper-level low to the west and the ridge to the northeast. The official forecast track lies slightly to the east of the previous forecast in the short term, and then is very close to the previous NHC track in days 3 to 5.
Gabrielle is expected to remain in a marginal environment during the next 2 to 3 days, with moderate southerly to southwesterly wind shear, low values of mid-level relative humidity and SSTs near 26-27C. No change in wind speed is predicted during the first two days. Thereafter, some strengthening is possible as Gabrielle moves on the northeast side of the upper-level low concurrent with the cyclone moving over warmer water. This is a typical situation for intensification, so the forecast wind speed is raised slightly at days 4-5. The intensity forecast is fairly consistent with the bulk of the typically reliable intensity models.
FORECAST POSITIONS AND MAX WINDS
INIT 04/1500Z 20.5N 33.8W 45 KT 50 MPH
12H 05/0000Z 21.0N 34.5W 45 KT 50 MPH
24H 05/1200Z 21.9N 35.6W 45 KT 50 MPH
36H 06/0000Z 23.1N 36.9W 45 KT 50 MPH
48H 06/1200Z 24.6N 38.4W 45 KT 50 MPH
72H 07/1200Z 28.6N 41.7W 50 KT 60 MPH
96H 08/1200Z 32.5N 45.5W 55 KT 65 MPH
120H 09/1200Z 36.5N 47.5W 55 KT 65 MPH
