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Tropical Depression Eight Forecast Discussion Number 2

2020-07-23 10:40:29| National Hurricane Center (Atlantic)

Issued at 400 AM CDT Thu Jul 23 2020 000 WTNT43 KNHC 230840 TCDAT3 Tropical Depression Eight Discussion Number 2 NWS National Hurricane Center Miami FL AL082020 400 AM CDT Thu Jul 23 2020 Satellite images and surface synoptic observations suggest that the depression has not strengthened thus far, although recent images show some increase in deep convection near the estimated center. The initial intensity estimate remains at 25 kt in agreement with surface data over the Gulf. The cyclone should remain in a relatively moist, low-shear environment during the next day or so. However, since the system is not well organized, only slow strengthening is forecast until the center reaches the coast. The NHC intensity forecast is near the upper range of the model guidance at this time. The center is not well-defined and the initial motion estimate is an uncertain 290/8 kt. This is more or less consistent with observations from NOAA data buoy 42001 over the central Gulf. A continued west-northwestward track is expected over the next day or so followed by a slight bend toward the west in response to some building of a mid-level ridge to the north of the cyclone. The official track forecast is a little faster than the previous one but not quite as fast as the latest dynamical model consensus. Key Messages 1. The depression is expected to strengthen and it could bring tropical-storm-force winds to portions of the Texas coast, where a tropical storm watch has been issued. 2. The depression is expected to produce heavy rains across portions of Louisiana and southern Texas. These rains could result in flash flooding. FORECAST POSITIONS AND MAX WINDS INIT 23/0900Z 26.0N 90.0W 25 KT 30 MPH 12H 23/1800Z 26.4N 91.0W 30 KT 35 MPH 24H 24/0600Z 27.1N 92.3W 30 KT 35 MPH 36H 24/1800Z 27.7N 94.0W 35 KT 40 MPH 48H 25/0600Z 28.0N 95.5W 35 KT 40 MPH 60H 25/1800Z 28.2N 97.0W 40 KT 45 MPH...ON COAST 72H 26/0600Z 28.2N 98.6W 35 KT 40 MPH...INLAND 96H 27/0600Z 28.0N 100.5W 20 KT 25 MPH...INLAND 120H 28/0600Z 28.0N 102.5W 15 KT 15 MPH...INLAND $$ Forecaster Pasch

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Hurricane Douglas Forecast Discussion Number 11

2020-07-23 04:43:16| National Hurricane Center (East Pacific)

Issued at 500 PM HST Wed Jul 22 2020 000 WTPZ43 KNHC 230243 TCDEP3 Hurricane Douglas Discussion Number 11 NWS National Hurricane Center Miami FL EP082020 500 PM HST Wed Jul 22 2020 Douglas's cloud pattern has improved quickly since the last advisory, with an eye becoming more distinct within an area of cold cloud tops and expanding outflow in all quadrants. The initial intensity has been increased to 85 kt. This is in agreement with the latest SATCON estimate and a blend of the latest ADT and SATCON estimates. The hurricane has another 24 hours or so over SSTs above 28C with very low vertical shear, and rapid intensification appears to be underway. Given the current satellite trends and the SHIPS RII showing a 50 percent chance of a 30-kt intensity increase in 24 h, the NHC forecast has been increased above the guidance in the short term, showing the system peaking at 110 kt in 24 h, although timing the peak intensity during rapid strengthening is quite difficult. By 36 h, SSTs cool along the forecast track but the shear remains low, which should result in gradual weakening. Late in the period, an increase in shear and a drier airmass should result in continued gradual weakening. Douglas is expected to be at or near hurricane intensity as it approaches the Hawaiian Islands on Sunday, and all interests there should monitor forecasts as they evolve over the next few days. The initial motion estimate is now toward the west-northwest or 285/15. Douglas should continue on a general west-northwestward motion for the next 72 hours under the influence of an expansive mid-level ridge extending across much of the central and eastern North Pacific. The track will turn more toward the west late in the period as Douglas moves near the Hawaiian Islands. The new NHC track forecast is very close to the previous one and lies near the middle of the guidance envelope close to the TVCE multi-model consensus. 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 and heavy rainfall could affect portions of the state beginning on 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. FORECAST POSITIONS AND MAX WINDS INIT 23/0300Z 12.5N 132.6W 85 KT 100 MPH 12H 23/1200Z 13.4N 134.7W 100 KT 115 MPH 24H 24/0000Z 14.6N 137.7W 110 KT 125 MPH 36H 24/1200Z 15.9N 140.8W 105 KT 120 MPH 48H 25/0000Z 17.1N 143.9W 90 KT 105 MPH 60H 25/1200Z 18.2N 146.9W 80 KT 90 MPH 72H 26/0000Z 19.2N 149.9W 70 KT 80 MPH 96H 27/0000Z 20.3N 155.5W 60 KT 70 MPH 120H 28/0000Z 21.0N 162.0W 50 KT 60 MPH $$ Forecaster Brennan

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Tropical Depression Eight Forecast Discussion Number 1

2020-07-23 04:42:45| National Hurricane Center (Atlantic)

Issued at 1000 PM CDT Wed Jul 22 2020 000 WTNT43 KNHC 230242 TCDAT3 Tropical Depression Eight Discussion Number 1 NWS National Hurricane Center Miami FL AL082020 1000 PM CDT Wed Jul 22 2020 Surface observations and data from the Air Force Hurricane Hunters indicate that the area of low pressure over the central Gulf of Mexico has developed a closed circulation and a well-defined center. In addition, recent satellite images show an area of deep convection expanding over the center. Based on those observations, advisories are being initiated on Tropical Depression Eight. The initial intensity is set at 25 kt based on the earlier reconnaissance data. The initial motion is an uncertain west-northwestward at 5 kt. A subtropical ridge to the northeast of the depression should cause it to continue moving in that general direction through Friday as it tracks across the northwestern Gulf of Mexico. A slight turn to the left is expected Friday night and Saturday as a ridge builds to the north of the system, taking the center of cyclone across the Texas coast and then inland over southern Texas. The models are in fairly good agreement on this scenario, and the NHC track forecast lies near the various consensus models. The depression is expected to be in generally light to moderate wind shear conditions, in a fairly moist environment, and over the warm waters of the Gulf of Mexico for the next couple of days, so some strengthening seems likely. However, since the depression is still in its formative stage, the rate of strengthening should be gradual. After the storm crosses the coast, steady weakening should commence. The NHC intensity forecast generally follows the IVCN and HCCA guidance. Key Messages 1. The depression is expected to strengthen and it could bring tropical-storm-force winds to portions of the Texas coast, where a tropical storm watch has been issued. 2. The depression is expected to produce heavy rains across portions of Louisiana and southern Texas. These rains could result in flash flooding. FORECAST POSITIONS AND MAX WINDS INIT 23/0300Z 25.9N 88.2W 25 KT 30 MPH 12H 23/1200Z 26.3N 89.3W 30 KT 35 MPH 24H 24/0000Z 27.0N 90.8W 30 KT 35 MPH 36H 24/1200Z 27.9N 92.4W 35 KT 40 MPH 48H 25/0000Z 28.2N 94.0W 35 KT 40 MPH 60H 25/1200Z 28.5N 95.3W 40 KT 45 MPH 72H 26/0000Z 28.7N 96.8W 35 KT 40 MPH...INLAND 96H 27/0000Z 28.8N 98.1W 25 KT 30 MPH...INLAND 120H 28/0000Z 28.7N 100.5W 20 KT 25 MPH...INLAND $$ Forecaster Cangialosi

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Tropical Storm Gonzalo Forecast Discussion Number 6

2020-07-23 04:35:15| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Wed Jul 22 2020 000 WTNT42 KNHC 230235 TCDAT2 Tropical Storm Gonzalo Discussion Number 6 NWS National Hurricane Center Miami FL AL072020 1100 PM AST Wed Jul 22 2020 A series of earlier microwave passes over Gonzalo reveal a small eye feature beneath a relatively ragged, Central Dense Overcast with associated -75.5C cloud tops. Based on the evidence of the small eye and a blend of the subjective and objective satellite intensity estimates, the initial intensity is raised to 50 kt for advisory. The intensity forecast philosophy remains the same as the previous advisory with a higher than normal degree of uncertainty in the latter half of the period as the cyclone moves through the Caribbean. Gonzalo should remain in an environment of relatively low shear, although the impacts of dry, stable air and large-scale subsidence could hamper further intensification in a few days. It's worth noting that the ECMWF Ensemble model is showing a pretty significant low- to mid-level easterly surge that spreads just to the north of the cyclone's forecast track and over the northeastern Caribbean in a couple of days. This predicted event could possibly curtail strengthening at that time. On the other hand, with the exception of the ECMWF, the global models now show the cyclone maintaining tropical storm strength while moving into the eastern Caribbean. The official intensity forecast is adjusted slightly above the previous forecast, hedging toward the HFIP HCCA consensus and the IVCN multi-model intensity aid solutions. It should also be noted that the small size of this system makes it susceptible to significant fluctuations in intensity, both upward and downward. The initial motion is estimated to be due west, or 270/10 kt. There is no change to the track forecast philosophy. Gonzalo is on the south side of a low- to mid-level tropospheric ridge, and this feature should steer the storm generally westward at a faster forward speed for the next few days. After that time, a motion toward the west-northwest is expected. The NHC track forecast is nudged a bit to the north of the previous one and is close to the various consensus aids. Interests in the Windward Islands should continue to monitor the progress of this system. A Hurricane Watch is now issued for Barbados. Key Messages 1. Gonzalo is expected to move near or over the southern Windward Islands this weekend, and could bring direct impacts from winds and heavy rainfall. While it is too soon to determine the magnitude and timing of those impacts, interests in the southern Windward Islands should monitor the progress of Gonzalo. FORECAST POSITIONS AND MAX WINDS INIT 23/0300Z 9.9N 45.9W 50 KT 60 MPH 12H 23/1200Z 10.0N 47.6W 60 KT 70 MPH 24H 24/0000Z 10.2N 50.0W 65 KT 75 MPH 36H 24/1200Z 10.6N 52.7W 70 KT 80 MPH 48H 25/0000Z 11.2N 55.5W 75 KT 85 MPH 60H 25/1200Z 11.8N 58.6W 70 KT 80 MPH 72H 26/0000Z 12.6N 61.8W 60 KT 70 MPH 96H 27/0000Z 14.3N 67.6W 50 KT 60 MPH 120H 28/0000Z 15.6N 73.1W 40 KT 45 MPH $$ Forecaster Roberts

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Hurricane Douglas Forecast Discussion Number 10

2020-07-22 22:39:10| National Hurricane Center (East Pacific)

Issued at 1100 AM HST Wed Jul 22 2020 000 WTPZ43 KNHC 222039 TCDEP3 Hurricane Douglas Discussion Number 10 NWS National Hurricane Center Miami FL EP082020 1100 AM HST Wed Jul 22 2020 Douglas's structure has continued to improve, with a more well-defined eye becoming apparent in visible and microwave satellite images. Subjective Dvorak intensity estimates from TAFB and SAB range from T4.0/65 kt and T5.0/90 kt, while the latest UW-CIMSS ADT is 4.0. Douglas's initial intensity is therefore raised to 70 kt as a blend of the satellite estimates. The hurricane has begun to gain some latitude, and the initial motion is just north of due west, or 275/14 kt. The track forecast reasoning has not changed since earlier this morning, with a persistent mid-tropospheric ridge to Douglas's north expected to be the main driving force for the entire 5-day forecast period. Douglas is forecast to turn west-northwestward by this evening, and then maintain that heading with some increase in forward speed through day 4 as it approaches the Hawaiian Islands. A bend back to the west is then expected at the end of the forecast period. The new NHC track forecast lies right along the forecast path from the previous advisory through 60 hours, although it has been shifted slightly north on days 3-5 based on an overall shift of the guidance envelope at those times. Confidence in the track forecast at this stage is rather high. Intensity-wise, low shear and sea surface temperature of 28-29C favor continued strengthening, potentially at a rapid rate for the next 24 hours. SHIPS, HCCA, and the Florida State Superensemble all bring the intensity near or at major hurricane strength in 24-36 hours, which qualifies as rapid intensification. The NHC intensity forecast is in line with these models and lies near the upper bound of the guidance envelope given the favorable conditions. Some weakening is expected to begin by 48 hours due to cooler waters, but since vertical shear is not expected to increase until around day 4, the weakening rate is likely to be gradual. This forecast increases the chance that Douglas could maintain hurricane intensity as it approaches the Hawaiian Islands, and all interests on the islands should monitor the forecasts as they evolve over the next few days. 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 and heavy rainfall could affect portions of the state beginning on 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. FORECAST POSITIONS AND MAX WINDS INIT 22/2100Z 12.1N 130.9W 70 KT 80 MPH 12H 23/0600Z 12.7N 132.9W 85 KT 100 MPH 24H 23/1800Z 13.8N 135.8W 100 KT 115 MPH 36H 24/0600Z 15.1N 138.9W 100 KT 115 MPH 48H 24/1800Z 16.4N 141.9W 90 KT 105 MPH 60H 25/0600Z 17.6N 145.0W 80 KT 90 MPH 72H 25/1800Z 18.7N 148.0W 75 KT 85 MPH 96H 26/1800Z 20.0N 154.0W 65 KT 75 MPH...NEAR HAWAII 120H 27/1800Z 21.0N 160.0W 55 KT 65 MPH...NEAR HAWAII $$ Forecaster Berg

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