Not much has changed overnight, thankfully. There have been little tweaks to some of the forecasts, and the model data has come into better agreement in some places. But no drastic changes. The “biggest” change is likely with Gonzalo. More on that below!
Here is a look at the big picture.
Notice how big and small some of the features are.
1. Hurricane Douglas
2. Tropical Storm Hanna
3. Tropical Storm Gonzalo
4. the next Wave
Gonzalo is particularly small. It reminds me of that scene from Aladdin…
Alrighty, on to the data from the NHC!
Hurricane Douglas
SUMMARY OF 1100 PM HST…0900 UTC…INFORMATION
———————————————–
LOCATION…15.7N 140.3W
ABOUT 1010 MI…1630 KM ESE OF HILO HAWAII
MAXIMUM SUSTAINED WINDS…130 MPH…215 KM/H
PRESENT MOVEMENT…WNW OR 295 DEGREES AT 18 MPH…30 KM/H
MINIMUM CENTRAL PRESSURE…954 MB…28.17 INCHES
DISCUSSION AND OUTLOOK
At 1100 PM HST (0900 UTC), the center of Hurricane Douglas was located near latitude 15.7 North, longitude 140.3 West. Douglas is moving toward the west-northwest near 18 mph (30 km/h), and this motion is expected to continue for the next few days with a gradual decrease in forward speed and a slight turn toward the west. On the forecast track Douglas will approach the Hawaiian Islands Saturday night, and be near those Islands on Sunday.
Maximum sustained winds are near 130 mph (215 km/h) with higher gusts. Douglas is a category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale. Gradual weakening is expected to begin on Friday and continue through the weekend. Douglas is forecast to be near hurricane strength when it approaches the Hawaiian Islands.
Hurricane-force winds extend outward up to 30 miles (45 km) from the center and tropical-storm-force winds extend outward up to 90 miles
(150 km).
Douglas continues to look impressive in satellite images, with a clear eye and symmetric convection in all quadrants. Broad outflow channels extend about 300 n mi in every direction from the cyclone, indicative of nearly zero wind shear. The latest Dvorak CI values from TAFB and SAB, as well as the recent UW/CIMSS ADT estimates are all T6.0, which supports keeping the initial advisory intensity at 115 kt.
Douglas is crossing the 26 C isotherm, and will continue to move over relatively cooler waters of about 25 C over the next day or so. This should cause the cyclone to begin weakening very soon. In about 48 h, Douglas is forecast to move back across the 26 C isotherm, but at the same time the cyclone is forecast to begin encountering a drier, more stable airmass and increasing vertical wind shear. Despite the warmer waters, these other more hostile environmental factors are expected to cause Douglas to gradually weaken for the remainder of the 5-day forecast period. The latest NHC forecast is changed little from the previous advisory, and is very close to a blend of the corrected consensus HCCA and the IVCN/ICON consensus aids.
Douglas is still moving quickly west-northwestward or 295/16 kt. A mid-level ridge to the north of the cyclone should keep moving the cyclone in the same general direction over the next couple of days. Over the weekend, as Douglas approaches the Hawaiian Islands, a more westward motion is forecast as another ridge builds to the north of the cyclone. There is some notable spread in the model guidance now compared to yesterday as Douglas approaches the Hawaiian Islands. The faster and southernmost guidance from the ECMWF takes the center of the cyclone over the big island, while the northernmost GFS and HWRF take the cyclone just north of the island chain. The other guidance, including the track consensus aids lie in between those solutions. The latest NHC forecast was nudged slightly northward between 48 h and 96 h, but still remains south of the consensus aids during those time periods. Otherwise, the NHC forecast was little changed from the previous one.
This is the last advisory issued by the National Hurricane Center on Douglas. Future information on this system can be found in Forecast/Advisories issued by the Central Pacific Hurricane Center beginning at 1500 UTC under AWIPS header HFOTCMCP2 and WMO header WTPA22 PHFO. For information specific to the Hawaiian Islands, users should continue to consult products from the National Weather Service Forecast Office in Honolulu, Hawaii, at www.weather.gov/hfo.
KEY MESSAGES
1. Douglas is expected to move near or over portions of the Hawaiian Islands this weekend, and there is an increasing chance that strong winds, dangerous surf, and heavy rainfall could affect portions of the state beginning Saturday night or Sunday. Interests on the Hawaiian Islands should continue to monitor the progress of Douglas and the official forecasts as they evolve over the next few days. Watches could be issued on Friday.
FORECAST POSITIONS AND MAX WINDS
INIT 24/0900Z 15.7N 140.3W 115 KT 130 MPH
12H 24/1800Z 16.7N 142.6W 105 KT 120 MPH
24H 25/0600Z 17.9N 145.7W 95 KT 110 MPH
36H 25/1800Z 19.0N 148.7W 85 KT 100 MPH
48H 26/0600Z 19.9N 151.7W 75 KT 85 MPH
60H 26/1800Z 20.5N 154.5W 65 KT 75 MPH…NEAR HAWAII
72H 27/0600Z 21.0N 157.1W 60 KT 70 MPH…NEAR HAWAII
96H 28/0600Z 22.0N 163.2W 50 KT 60 MPH
120H 29/0600Z 22.4N 170.0W 45 KT 50 MPH
HAZARDS AFFECTING LAND
— SURF: Swells generated by Douglas are expected to begin affecting portions of the Hawaiian Islands on Saturday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.
MODEL DATA
The model data lines up pretty much with what the NHC is forecasting. The forecast is for Douglas to begin to reall weaken in the coming 48 hours and pass by Hawaii as a weak hurricane or strong tropical storm.
Model guidance shows the decline in strength.
Keep in mind that even Category 1 Hurricanes do damage. So don’t sleep on this one. But also recognize that it is likely to weaken a big before it rolls through the Islands.
Tropical Storm Hanna
Hurricane Hunters are fun people.
In addition to data collection we drew a nice arrow in the sky to show you the general direction TS #Hanna is going. pic.twitter.com/gmx6Bqxsq5
— Tropical Nick Underwood (@TheAstroNick) July 24, 2020
The NOAA Hurricane Hunters were out in Tropical Storm Hanna to collect valuable data to plug into the modeling. As Tropical Storm Hanna continues to drift west toward Texas, people along the southern Texas coast should be continuing to prepare for heavy rain, strong wind and coastal flooding.
SUMMARY OF 1000 AM CDT…1500 UTC…INFORMATION
———————————————–
LOCATION…27.2N 93.2W
ABOUT 260 MI…420 KM E OF CORPUS CHRISTI TEXAS
ABOUT 260 MI…420 KM E OF PORT MANSFIELD TEXAS
MAXIMUM SUSTAINED WINDS…45 MPH…75 KM/H
PRESENT MOVEMENT…WNW OR 285 DEGREES AT 9 MPH…15 KM/H
MINIMUM CENTRAL PRESSURE…1000 MB…29.53 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY: The Tropical Storm Watch from San Luis Pass to High Island Texas has been discontinued.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Tropical Storm Warning is in effect for…
* Mouth of the Rio Grande to San Luis Pass Texas
A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area, in this case within 24 to 36 hours.
Interests along the Texas and Louisiana coast should monitor the progress of this system.
For storm information specific to your area, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office.
DISCUSSION AND OUTLOOK
At 1000 AM CDT (1500 UTC), the center of Tropical Storm Hanna was located by NOAA reconnaissance aircraft near latitude 27.2 North, longitude 93.2 West. Hanna is moving toward the west-northwest near 9 mph (15 km/h), and this motion should continue today. A turn toward the west is expected tonight, followed by a westward to west-southwestward motion through the weekend. On the forecast track, center of Hanna should make landfall along the Texas coast within the warning area Saturday afternoon or evening.
Maximum sustained winds have increased to near 45 mph (75 km/h) with higher gusts. Gradual strengthening is expected until the tropical cyclone makes landfall. Steady weakening is expected after Hanna moves inland.
Tropical-storm-force winds extend outward up to 60 miles (95 km) from the center. During the past few hours, a ship located east of the center reported a sustained wind of 44 mph (70 km/h).
Reports from the NOAA reconnaissance aircraft indicate that the minimum central pressure is 1000 mb (29.53 inches).
Reports from a NOAA reconnaissance aircraft this morning and nearby ship D5DY4 indicate that Hanna has strengthened a little. However,
the aircraft data also showed that Hanna’s center had moved or reformed a little farther north near the northern edge of the
convective cloud mass. A partial SSMI/S pass around 1231Z suggested that a mid-level eye feature could be forming, but it also possible
that a dry slot may be intruding into the cloud shield from the northwest and west. The initial intensity of 40 kt is based on
aircraft SFMR surface winds of 38-40 kt, and the 1200Z D5DY5 ship report of 48 kt at 89 meters elevation, which reduces to a 38-kt
10-meter wind speed.
Even with the earlier northwestward jump in the center position, reconnaissance and microwave satellite data indicate that Hanna’s motion is still west-northwestward or 285/08 kt. There remains no significant change to the previous official track forecast or reasonings over the past couple of days. The latest NHC model guidance remains in good agreement that mid-level ridge will build to the north and northwest of Hanna over the next couple of days, resulting in the cyclone turning westward by tonight and on Saturday. It should then turn west-southwestward Saturday night and Sunday. The new NHC forecast track continues to show the center making landfall along the south-central coast of Texas within the tropical storm warning area Saturday afternoon or evening, which is in good agreement with the various consensus models.
Hanna’s convective cloud shield remains very asymmetrical with the bulk of the convection confined to the southern semicircle despite the otherwise symmetrical and expanding upper-level outflow pattern. More recently, some deep convection has developed near the center and the aforementioned possible mid-level eye feature. Hanna is forecast to remain in relatively low vertical wind shear regime and over SSTs of 30C or more, a combination that typically favors significant intensification. However, nearby dry mid-level air noted in 1200Z soundings from Corpus Christi and Brownsville has been eroding and preventing convection from developing in the northwest quadrant and near the center, which has inhibited strengthening over the past couple of days despite the low shear conditions. The latest global model guidance shows the dry air mixing out in about 24 h just prior to landfall, which should allow for at least gradual strengthening until landfall occurs in about 30 h or so. However, if an eyewall forms during the next 12 h, then it is possible that Hanna could be near 60 kt when it makes landfall. The new NHC intensity forecast is similar to the previous advisory, and is a blend of the IVCN and HCCA consensus intensity forecasts.
KEY MESSAGES
1. Hanna is forecast to strengthen and it is expected to bring tropical-storm-force winds to portions of the Texas coast, where a tropical storm warning is in effect.
2. Hanna is expected to produce heavy rains across portions of southern Texas. These rains could result in flash flooding and isolated minor to moderate river flooding.
FORECAST POSITIONS AND MAX WINDS
INIT 24/1500Z 27.2N 93.2W 40 KT 45 MPH
12H 25/0000Z 27.5N 94.6W 45 KT 50 MPH
24H 25/1200Z 27.4N 96.2W 55 KT 65 MPH
36H 26/0000Z 27.3N 97.6W 50 KT 60 MPH…INLAND
48H 26/1200Z 27.0N 99.0W 35 KT 40 MPH…INLAND
60H 27/0000Z 26.3N 100.4W 25 KT 30 MPH…INLAND
72H 27/1200Z 25.7N 101.6W 15 KT 15 MPH…POST-TROP/REMNT LOW
96H 28/1200Z…DISSIPATED
HAZARDS AFFECTING LAND
— WIND: Tropical storm conditions are expected in the warning area by tonight or Saturday morning.
— RAINFALL: Hanna is expected to produce 4 to 8 inches of rain with isolated maximum totals of 12 inches through Sunday night in south Texas. This rain may result in life-threatening flash flooding, rapid rises on small streams, and isolated minor to moderate river flooding in south Texas.
3 to 5 inches of rain is expected along the upper Texas and Louisiana coasts, and inland to the Mexican states of Coahuila, Nuevo Leon, and northern Tamaulipas.
— STORM SURGE: The combination of storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide…
Mouth of the Rio Grande to High Island including Corpus Christi Bay, Matagorda Bay, and Galveston Bay…1-3 ft
The deepest water will occur along the immediate coast near and to the right of the landfall location. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office.
— SURF: Swells generated by Hanna are expected to increase and affect much of the Texas and Louisiana coasts during the next few days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.
MODEL DATA
Originally there was some debate within the model data about if this storm was going to be able to make a run at developing into a hurricane. Now, that looks less likely.
A strong Tropical Storm, sure. But it may just simply ‘run out of time’ to develop into a hurricane, despite the reasonably favorable environment.
Tropical Storm Gonzalo
SUMMARY OF 1100 AM AST…1500 UTC…INFORMATION
———————————————–
LOCATION…10.0N 54.2W
ABOUT 485 MI…780 KM E OF THE SOUTHERN WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS…50 MPH…85 KM/H
PRESENT MOVEMENT…W OR 275 DEGREES AT 18 MPH…30 KM/H
MINIMUM CENTRAL PRESSURE…1002 MB…29.59 INCHES
DISCUSSION AND OUTLOOK
At 1100 AM AST (1500 UTC), the center of Tropical Storm Gonzalo was located near latitude 10.0 North, longitude 54.2 West. Gonzalo is moving toward the west near 18 mph (30 km/h). A general westward- to west-northwestward motion is expected during the next couple of days. On the forecast track, the center of Gonzalo will approach the southern Windward Islands tonight and then move across the islands on Saturday and over the eastern Caribbean Sea on Sunday.
Maximum sustained winds are near 50 mph (85 km/h) with higher gusts. There is considerable uncertainty in the intensity forecast, but some strengthening is still possible during the next day or so before Gonzalo reaches the southern Windward Islands. Weakening is expected after Gonzalo moves into the Caribbean Sea, and the cyclone is expected to dissipate by the middle of next week.
Gonzalo is a small tropical cyclone. Tropical-storm-force winds extend outward up to 25 miles (35 km) from the center.
Gonzalo continues to produce bursts of deep convection, especially in the southeast quadrant, but has not become any better organized overall since the last advisory. Microwave imagery overnight indicated the low-level structure of Gonzalo is still largely intact, but this has not translated into better convective organization. ASCAT data valid shortly after 12Z revealed that Gonzalo has accelerated west faster than anticipated and has not strengthened. In fact the strongest winds in the ASCAT data were only 30-35 kt. The resolution of ASCAT likely limits its ability to sample the actual max winds of small storms like Gonzalo, but it is another indication that the cyclone has not strengthened and could be weakening. The initial intensity for this advisory is set at 45 kt, based primarily on the latest TAFB Dvorak fix and the UW-CIMSS SATCON. An Air Force Reserve reconnaissance aircraft scheduled to investigate the storm this afternoon will provide a more information about Gonzalo’s intensity and structure.
Due primarily to the adjusted initial position, the NHC track forecast has been adjusted a fair amount west and south of the previous advisory. Overall Gonzalo is still forecast to move generally westward or west-northwestward through the period, steered by the subtropical ridge to the north. The new NHC forecast lies between the old forecast, adjusted for the new initial position, and the HFIP Corrected Consensus.
The intensity guidance is generally lower than it has been for the last day or so, and none of the operational models forecast Gonzalo to reach hurricane strength. Unfortunately, small storms like Gonzalo are often subject to large swings in intensity, up or down, and that aspect of the forecast remains highly uncertain, even though the spread in the guidance is not particularly high. The NHC forecast has been adjusted only slightly lower for this cycle and is now above all of the guidance at the time the system is forecast to pass through the Windward Islands. A larger adjustment could be made later today if the most recent model trends continue, or if the recon mission finds that Gonzalo is even weaker than the current estimates.
KEY MESSAGES
1. Gonzalo is forecast to bring tropical storm conditions across portions of the southern Windward Islands Saturday and Saturday night. Hurricane and Tropical Storm Warning and Watches are currently in effect for some of the islands. Interests in the southern Windward Islands should monitor the progress of Gonzalo and follow any advice given by local officials.
2. Gonzalo is expected to produce heavy rain over portions of the southern Windward Islands. This could lead to life-threatening flash flooding.
FORECAST POSITIONS AND MAX WINDS
INIT 24/1500Z 10.0N 54.2W 45 KT 50 MPH
12H 25/0000Z 10.5N 56.0W 50 KT 60 MPH
24H 25/1200Z 11.4N 59.1W 55 KT 65 MPH
36H 26/0000Z 12.4N 62.3W 60 KT 70 MPH
48H 26/1200Z 13.0N 65.7W 50 KT 60 MPH
60H 27/0000Z 13.7N 69.0W 40 KT 45 MPH
72H 27/1200Z 14.0N 72.0W 30 KT 35 MPH
96H 28/1200Z…DISSIPATED
HAZARDS AFFECTING LAND
—WIND: Tropical storm conditions are expected within portions of the Tropical Storm Warning area on Saturday. Hurricane conditions are possible on Saturday within the Hurricane Watch area.
— RAINFALL: Gonzalo is expected to produce total rain accumulations of 2 to 5 inches, with isolated maximum amounts of 8 inches in Barbados and the Windward Islands through Sunday night. Gonzalo is also expected to produce total rain accumulations of 2 to 4 inches in Trinidad and Tobago as well as 1 to 2 inches over northeastern Venezuela. Rainfall in Barbados and the Windward Islands could lead to life-threatening flash floods.
MODEL DATA
The model data – and the forecast from the NHC – are in pretty decent agreement. Everyone is feeling pretty good about where Gonzalo is going to be during the next five days.
It will be moving through the Greater and Lesser Antilles, and then into the Caribbean. Given it’s size, though, there is some discrepancy between the modeling and the forecast.
That discrepancy is due to the size of the storm. Since tropical-storm-force winds extend out from the only 25 miles, there isn’t much for the computers to really ‘latch on to’ to produce a forecast. So, in this case, the humans are much better at deciphering what will happen. And the forecast now is that Gonzalo will remain a tropical storm until it dissipates in about four or five days.
The next Wave
The next wave coming off the African coast has a lot of meteorologists attention given a lot of different variables coming into alignment simultaneously. Things like, (1) the amount of environmental shear will be a bit lower across the open Atlantic, (2) the water temperature is running above average, (3) the dry saharan dust hasn’t been as pronounced recently, (4) a Kelvin Wave will be passing through the region, (5) two large ridges of high pressure should help guide the wave toward the west, instead of allowing it to re-curve northward as early.
Among other things to watch.
By next Friday, the 00z run of the ECMWF puts the next wave into the Caribbean.
Even the EPS ensembles show a bit of a ‘crinkle’ in the same area.
So it is worth watching, for sure. Since there is no “invest” tag on this wave, yet, the spaghetti models are not run and there are no intensity charts, either. But as this moves out into the open Atlantic, it will likely be designated “Invest 92L” unless something else forms first.
Based ont he latest data, the timetable on this next one would put it near the Gulf/Bahamas/Yucatan region in the August 3rd/4th timeframe. If – and that is still an if, at this point – it makes it there.
