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Hurricane Kiko Forecast Discussion Number 13
2019-09-15 16:54:13| National Hurricane Center (East Pacific)
Issued at 800 AM PDT Sun Sep 15 2019 000 WTPZ43 KNHC 151454 TCDEP3 Hurricane Kiko Discussion Number 13 NWS National Hurricane Center Miami FL EP132019 800 AM PDT Sun Sep 15 2019 Kiko has become a very powerful hurricane overnight, with a warm eye and strong eyewall convection. The cloud pattern is also fairly symmetric, except favoring the western semicircle slightly due to some easterly shear. The initial wind speed is set to 115 kt, which matches the latest ADT and TAFB estimates. The hurricane should be near its peak intensity today while it in is a low-shear, marginal warm-water environment. While those conditions don't change that much during the next few days, Kiko is forecast to be moving fairly slowly over that time, which will likely stir up some cooler waters and help weaken the convection. A steadier weakening is expected at long-range due to an increase in shear. The new forecast is somewhat lower than the last one, but higher than the model consensus. It isn't out of the realm of possibility that Kiko could transition into an annular hurricane, which tend to maintain their intensities higher than average, so I'm hesitant to reduce the forecast too much for now. Kiko is moving westward at about 6 kt. A mid-level ridge to the north of the cyclone is forecast to remain in place for about the next two days, keeping the hurricane on a slow westward track. A weakness or even a break in the ridge is then forecast by all of the models due to a mid-latitude trough, with perhaps a restrengthening of the ridge at long range. There's been a subtle model trend toward supporting the ridge remaining weak but intact, which would favor Kiko moving very slowly westward instead of any significant rightward turn. The latest NHC prediction places a greater weight on the UKMET and ECMWF models and their ensembles, which generally favor the weak ridge scenario. No significant changes were made to the previous forecast track, but the long-range track confidence is low due to the large model spread at that time. FORECAST POSITIONS AND MAX WINDS INIT 15/1500Z 17.0N 121.1W 115 KT 130 MPH 12H 16/0000Z 17.1N 122.0W 110 KT 125 MPH 24H 16/1200Z 17.3N 123.2W 105 KT 120 MPH 36H 17/0000Z 17.4N 124.1W 95 KT 110 MPH 48H 17/1200Z 17.5N 125.0W 85 KT 100 MPH 72H 18/1200Z 17.5N 126.7W 70 KT 80 MPH 96H 19/1200Z 18.0N 129.0W 65 KT 75 MPH 120H 20/1200Z 18.5N 131.5W 50 KT 60 MPH $$ Forecaster Blake
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Tropical Storm Humberto Forecast Discussion Number 12
2019-09-15 16:54:13| National Hurricane Center (Atlantic)
Issued at 1100 AM EDT Sun Sep 15 2019 000 WTNT44 KNHC 151454 TCDAT4 Tropical Storm Humberto Discussion Number 12 NWS National Hurricane Center Miami FL AL092019 1100 AM EDT Sun Sep 15 2019 Visible and passive microwave satellite imagery indicate that Humberto's inner-core region has improved markedly since early this morning, including the development of a small but ragged mid-level eye. In addition, significant dry air entrainment that has been plaguing the cyclone since its formation appears to have abated based on the recent development of deep convection in the dry slot located in the southern semicircle of Humberto's circulation. Anticyclonic outflow has also been increasing in all quadrants, along with a hint of cloud-filled eye in recent visible imagery. Buoy 41010 located just west of the center recently reported a pressure of 1001.8 mb and 41-kt winds at 4-meters elevation. The initial intensity has been increased to 55 kt based on a Dvorak intensity estimate of T3.5/55 kt from TAFB. AN Air Force Reserve reconnaissance aircraft will reconnoiter Humberto this afternoon, providing more detailed information on the cyclone's intensity. The initial motion estimate is 350/06 kt, based mainly on microwave satellite fix positions. NHC model guidance remains in excellent agreement on Humberto moving slowly northward through a break in the subtropical ridge today and tonight, then making a sharp turn toward the northeast on Monday when the cyclone passes north of the narrow east-west oriented ridge axis. On days 2-5, the tropical cyclone is forecast to gradually accelerate toward the northeast and east-northeast under the influence of increasing westerlies ahead of a deepening mid-latitude trough forecast to dig southeastward out of Canada and into the extreme northwestern Atlantic Ocean. The new official forecast track is very similar to the previous advisory track, and lies close to a blend of the tightly packed consensus track models. Humberto now appears to be well on its way to becoming a hurricane fairly soon based on the newly formed central dense overcast and mid-level eye feature. Although the large-scale shear is fairly large in the SHIPS intensity models, the shear directly over the center of Humberto is forecast to remain low for the next 48 hours or so, which should allow for steady strengthening. By 72 hours, the cyclone is forecast to be situated in the right-rear quadrant of a strong, anticyclonically curved jet maximum. The associated upper-level divergence is expected to induce strong pressure falls and strengthening despite the vertical shear increasing to more than 30 kt. By 96 hours and beyond, slightly cooler waters, much drier air, and very hostile shear conditions of more than 40 kt should cause steady weakening. The new NHC intensity forecast follows the trend of the previous advisory, but now shows Humberto reaching peak intensity in 72 hours, coincident with the warmest water temperatures of about 29C and greatest jetstream dynamical forcing. Large swells from Humberto will affect portions of the northwestern Bahamas and southeastern United States coast during the next few days. These swells are expected to produce dangerous surf conditions and life-threatening rip currents. See products issued by your local weather office for additional information. FORECAST POSITIONS AND MAX WINDS INIT 15/1500Z 28.9N 77.9W 55 KT 65 MPH 12H 16/0000Z 29.5N 77.7W 65 KT 75 MPH 24H 16/1200Z 30.0N 77.1W 70 KT 80 MPH 36H 17/0000Z 30.3N 75.9W 80 KT 90 MPH 48H 17/1200Z 30.7N 74.4W 85 KT 100 MPH 72H 18/1200Z 31.6N 69.6W 95 KT 110 MPH 96H 19/1200Z 34.5N 62.8W 85 KT 100 MPH 120H 20/1200Z 39.0N 57.0W 65 KT 75 MPH $$ Forecaster Stewart
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Tropical Storm Humberto Forecast Discussion Number 11
2019-09-15 10:56:09| National Hurricane Center (Atlantic)
Issued at 500 AM EDT Sun Sep 15 2019 000 WTNT44 KNHC 150856 TCDAT4 Tropical Storm Humberto Discussion Number 11 NWS National Hurricane Center Miami FL AL092019 500 AM EDT Sun Sep 15 2019 Since reconnaissance aircraft departed the storm after midnight, the overall cloud pattern of Humberto has not changed appreciably. Both the earlier aircraft data and a blend of the most recent subjective satellite intensity estimates from SAB and TAFB still support an initial intensity of 50 kt. While there is significant banding evident over the northern and eastern portions of the circulation, the cyclone has not be able to maintain convection over the center, likely due to some mid-level dry air that has wrapped around the southwestern and southern part of the system. As Humberto moves slowly northward today, it will be over warm water and generally within low vertical wind shear. This should allow for strengthening, and the NHC foreast continues to calls for Humberto to become a hurricane later today or tonight. Additional strengthening is likely after that time when the storm recurves and remains within favorable environmental conditions. Late in the period, Humberto is forecast to interact with an approaching mid-latitude trough, and increasing shear ahead of that system is likely to cause weakening. This interaction should also begin Humberto's transition to an extratropical cyclone. The updated NHC intensity forecast is essentially unchanged from the previous advisory and is in best agreement with the HFIP corrected consensus model. Humberto continues to be steered north-northwestward at about 6 kt by a mid-level ridge over the western Atlantic. The tropical storm should turn northward and slow down later today as a weakness develops in the ridge. On Monday, a broad trough over the the northeastern United States is expected to turn Humberto northeastward, and then east-northeastward away from the United States. The dynamical models remain in good agreement on the overall track forecast scenario but there are some differences in the forward speed of Humberto after the east-northeastward turn. The latest NHC track is similar to, but a little slower than, the previous advisory. The new track forecast is closest to the multi-model consensus to account for the forward speed differences among the guidance. Large swells from Humberto will affect portions of the northwestern Bahamas and southeastern United States coast during the next few days. These swells are expected to produce dangerous surf conditions and life-threatening rip currents. See products issued by your local weather office for additional information. FORECAST POSITIONS AND MAX WINDS INIT 15/0900Z 28.3N 77.7W 50 KT 60 MPH 12H 15/1800Z 29.0N 77.9W 60 KT 70 MPH 24H 16/0600Z 29.6N 77.6W 65 KT 75 MPH 36H 16/1800Z 30.1N 76.7W 70 KT 80 MPH 48H 17/0600Z 30.5N 75.3W 75 KT 85 MPH 72H 18/0600Z 31.3N 71.2W 90 KT 105 MPH 96H 19/0600Z 33.5N 64.5W 95 KT 110 MPH 120H 20/0600Z 38.0N 58.0W 70 KT 80 MPH $$ Forecaster Brown
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Hurricane Kiko Forecast Discussion Number 12
2019-09-15 10:55:11| National Hurricane Center (East Pacific)
Issued at 200 AM PDT Sun Sep 15 2019 000 WTPZ43 KNHC 150855 TCDEP3 Hurricane Kiko Discussion Number 12 NWS National Hurricane Center Miami FL EP132019 200 AM PDT Sun Sep 15 2019 Kiko has continued to strengthen overnight and is now characterized by a cold ring of convection with cloud top temperatures below -70 degrees Celsius surrounding a clearing, well-defined eye. Both subjective and objective satellite intensity estimates have increased, and a blend of these estimates indicate an initial intensity of 110 kt. The improved appearance and structure of Kiko over the past several hours suggests that some additional strengthening is possible today, and the official forecast makes Kiko a category 4 hurricane by this afternoon. The intensity forecast beyond that time becomes challenging. Dynamical and statistical guidance unanimously weaken Kiko over the next few days. However, other than a slight increase in northeasterly shear indicated in SHIPS guidance, there are no other environmental indicators that stand out as a good reason for Kiko to weaken as quickly as shown by that guidance. It is also interesting to note that there is significant model spread in the forecast position of Kiko by 72 hours. Some of the guidance places Kiko over cool SSTs by day 3, while some solutions keep Kiko over warmer water. The official foreast, which is similar to the previous one, does indicate some weakening through 72 hours, but at a slower rate than the majority of the guidance since the latest forecast has trended southward over warm water. After 72 hours, increasing southwesterly shear from an upper-level trough to the northwest of Kiko should cause steady weakening after that time. Kiko is moving just south of due west, or 265/7 kt. A mid level ridge to the north of the hurricane should keep it generally on a west or west-northwestward track for the next couple of days. As mentioned previously, the models diverge by 72 hours as they differ in how they handle a mid to upper-level trough approaching California from the west. The northernmost solutions produce a break in the ridge with a sharper trough. The southern solutions keep the ridge in tact. Based on the continuation of a slight southward trend in the guidance, and the southward bias in the actual track of the cyclone recently, I am placing a little more weight on the southern solutions. However, given the large spread beyond 72 hours, the track confidence during that time is low. FORECAST POSITIONS AND MAX WINDS INIT 15/0900Z 16.9N 120.7W 110 KT 125 MPH 12H 15/1800Z 16.9N 121.8W 115 KT 130 MPH 24H 16/0600Z 17.2N 122.9W 105 KT 120 MPH 36H 16/1800Z 17.5N 124.0W 100 KT 115 MPH 48H 17/0600Z 17.6N 124.9W 95 KT 110 MPH 72H 18/0600Z 17.8N 126.6W 80 KT 90 MPH 96H 19/0600Z 18.1N 128.4W 65 KT 75 MPH 120H 20/0600Z 18.5N 131.0W 55 KT 65 MPH $$ Forecaster Latto
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Tropical Storm Humberto Forecast Discussion Number 10
2019-09-15 04:34:07| National Hurricane Center (Atlantic)
Issued at 1100 PM EDT Sat Sep 14 2019 000 WTNT44 KNHC 150233 TCDAT4 Tropical Storm Humberto Discussion Number 10 NWS National Hurricane Center Miami FL AL092019 1100 PM EDT Sat Sep 14 2019 Humberto is gradually strengthening. Both the NOAA and Air Force Hurricane Hunters have been investigating the storm this evening and they have found that the cyclone is a little stronger. Based on that data, the initial wind speed is nudged upward to 50 kt and the minimum pressure is around 1000 mb. Satellite images also show that the storm's structure is improving with an inner core trying to form and banding features becoming better defined to the north of the center. Doppler radar data from the NOAA P-3 aircraft indicate that the cyclone has become less titled in the vertical, suggesting that the shear has lessened over the system. However, there is still some signs of dry air being wrapped into the southern side of the circulation. Satellite and aircraft fixes indicate that the storm is moving north-northwestward at about 5 kt, steered by a mid-level ridge to its north-northeast over the western Atlantic. Humberto is expected to slow down and turn northward on Sunday well off the coast of east-central Florida as it moves into a developing weakness in the ridge. After that time, a turn to the northeast and then the east-northeast with a gradual increase in forward speed is predicted as Humberto moves along with the flow near the base of a large scale trough. The track models are in relatively good agreement, and only small changes were made to the previous forecast. The tropical storm is likely to continue strengthening during the next 3 to 4 days as it remains in relatively low wind shear conditions and over the warm Gulf Stream waters. Beyond that time, an increase in wind shear associated with an approaching shortwave trough will likely cause some weakening. The NHC intensity forecast is slightly higher than the previous one and shows Humberto becoming a hurricane in about 24 hours with additional strengthening thereafter. This forecast is in best agreement with the intensity consensus models HCCA, IVDR, and IVCN. The global models suggest that as Humberto gains latitude and intensifies, its wind field will gradually expand, and that is reflected in the NHC wind radii forecast. FORECAST POSITIONS AND MAX WINDS INIT 15/0300Z 27.6N 77.3W 50 KT 60 MPH 12H 15/1200Z 28.5N 77.8W 60 KT 70 MPH 24H 16/0000Z 29.3N 77.8W 65 KT 75 MPH 36H 16/1200Z 29.9N 77.1W 70 KT 80 MPH 48H 17/0000Z 30.4N 75.8W 75 KT 85 MPH 72H 18/0000Z 31.2N 72.0W 90 KT 105 MPH 96H 19/0000Z 33.0N 65.6W 95 KT 110 MPH 120H 20/0000Z 36.9N 58.9W 75 KT 85 MPH $$ Forecaster Cangialosi
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