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Hurricane Marie Forecast Discussion Number 11

2020-10-01 22:43:16| National Hurricane Center (East Pacific)

Issued at 200 PM PDT Thu Oct 01 2020 000 WTPZ43 KNHC 012043 TCDEP3 Hurricane Marie Discussion Number 11 NWS National Hurricane Center Miami FL EP182020 200 PM PDT Thu Oct 01 2020 An eye has formed in visible and infrared satellite imagery since the issuance of the previous advisory, and the surrounding convection continues to have cold cloud tops (as cold as -83C). The width of the coldest tops were a little thin on the southwest side at 1800 UTC, and because of this, subjective and objective intensity estimates were still 90 kt. Since that time, the eye has become more distinct and the convection is becoming more symmetric around the eye, and the initial intensity is therefore set at 95 kt. Marie's initial position has been adjusted to the south just a bit now that the center is more apparent with the eye formation. This yields a current westward motion of 280/14 kt. The atmospheric features responsible for steering Marie during the forecast period will be a mid-tropospheric ridge centered over the southwestern United States and a mid- to upper-level low located to the west over the Pacific. The interplay between these features is likely to cause some wiggles in Marie's future track, but for the most part the hurricane will be moving west-northwestward or northwestward through day 5. The spread in the guidance increases toward the end of the forecast period, with the GFS turning more northward and the ECMWF maintaining a west-northwestward motion. The other deterministic models are in between these two solutions, clustered very close to the various multi-model consensus aids, and that is where the NHC forecast also lies for this advisory. The environment appears conducive for this phase of rapid intensification to continue, at least for the next 24 hours. Deep-layer shear is just about to decrease to 10 kt or less, and Marie will remain over waters of high ocean heat content for the next 24-36 hours. The intensity guidance decreased a bit on this cycle, which seems odd given the ongoing intensification trend and the favorable environmental conditions. The SHIPS model does still show that the chance for rapid intensification to continue is 3 to 5 times higher than the climatological mean, and therefore the NHC intensity forecast maintains continuity from the previous advisory, showing a peak intensity of 120 kt. This forecast is above the highest intensity models by about 10-15 kt. Weakening is still anticipated, particularly after 48 hours, due to Marie moving over cooler waters and being affected by increasing southwesterly shear. FORECAST POSITIONS AND MAX WINDS INIT 01/2100Z 15.1N 120.9W 95 KT 110 MPH 12H 02/0600Z 15.8N 122.8W 115 KT 130 MPH 24H 02/1800Z 16.7N 125.0W 120 KT 140 MPH 36H 03/0600Z 17.8N 126.8W 115 KT 130 MPH 48H 03/1800Z 18.8N 128.2W 100 KT 115 MPH 60H 04/0600Z 19.7N 129.4W 85 KT 100 MPH 72H 04/1800Z 20.3N 130.9W 70 KT 80 MPH 96H 05/1800Z 21.4N 133.9W 55 KT 65 MPH 120H 06/1800Z 23.0N 136.3W 35 KT 40 MPH $$ Forecaster Berg

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Hurricane Marie Forecast Discussion Number 10

2020-10-01 16:37:26| National Hurricane Center (East Pacific)

Issued at 800 AM PDT Thu Oct 01 2020 000 WTPZ43 KNHC 011437 TCDEP3 Hurricane Marie Discussion Number 10 NWS National Hurricane Center Miami FL EP182020 800 AM PDT Thu Oct 01 2020 Marie has continued to become better organized this morning. An AMSR image from just after 09Z showed a closed mid-level eyewall, and conventional satellite imagery shows an increasingly symmetric cloud pattern with very cold cloud tops, colder than -80C, around the center. The current intensity estimate is set at 90 kt in agreement with Dvorak classifications from both TAFB and SAB. Marie is moving over SSTs warmer than 28 deg C and in a moist, low-shear atmospheric environment. The SHIPS guidance still shows a significant probability of rapid intensification through tonight, so Marie is likely to become a major hurricane quite soon. The official forecast is a little above the latest corrected model consensus. In a couple of days, the hurricane should be crossing the SST gradient and encountering cooler waters, so a weakening trend is anticipated to be underway within 48 hours. The estimated initial motion is west-northwestward, or 285/15 kt. For the next couple of days, Marie should continue to move along the southern periphery of a mid-tropospheric ridge associated with a high pressure system centered over California. A slight turn to the right with some deceleration is expected during the forecast period due to a weakness in the ridge near 130W longitude. By the end of the period, Marie is likely to turn toward the northwest while it moves through this weakness. The official track forecast lies very close to the latest multi-model consensus, TVCE, prediction. FORECAST POSITIONS AND MAX WINDS INIT 01/1500Z 15.2N 119.5W 90 KT 105 MPH 12H 02/0000Z 15.9N 121.7W 110 KT 125 MPH 24H 02/1200Z 16.8N 124.1W 120 KT 140 MPH 36H 03/0000Z 17.8N 126.2W 120 KT 140 MPH 48H 03/1200Z 18.8N 127.9W 105 KT 120 MPH 60H 04/0000Z 19.6N 129.3W 90 KT 105 MPH 72H 04/1200Z 20.4N 130.7W 75 KT 85 MPH 96H 05/1200Z 21.7N 133.7W 60 KT 70 MPH 120H 06/1200Z 23.8N 136.2W 40 KT 45 MPH $$ Forecaster Pasch

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Hurricane Marie Forecast Discussion Number 9

2020-10-01 10:35:18| National Hurricane Center (East Pacific)

Issued at 200 AM PDT Thu Oct 01 2020 000 WTPZ43 KNHC 010835 TCDEP3 Hurricane Marie Discussion Number 9 NWS National Hurricane Center Miami FL EP182020 200 AM PDT Thu Oct 01 2020 Recent microwave data and satellite images indicate that Marie has become much better organized over the past several hours, with a nearly completely closed eye noted in a 0451Z AMSU composite microwave overpass. The initial intensity has been increased to 80 kt, based on a blend of the latest satellite intensity estimates from TAFB, SAB, and the UW-CIMMS ADT and SATCON. Marie appears to have resumed its anticipated rapid intensification (RI), and this RI should continue for the next day or so while the hurricane remains in an environment of very low vertical wind shear while over warm waters. After 48 h, the cyclone is forecast to begin moving over progressively cooler waters, while encountering increasing vertical wind shear and a drier, more stable atmospheric environment. These factors should cause Marie to begin weakening by Saturday. Rapid weakening could occur by late this weekend when the cyclone is expected to be over waters with SSTs cooler than 26 degrees C while vertical wind shear becomes greater than 25 kt. The latest NHC intensity forecast is very close to the HFIP corrected consensus aid HCCA and the DSHP guidance. The initial motion is 280/15 kt. Marie is forecast to continue moving westward around a subtropical ridge to its north and northeast for the next 12 to 24 hours. A gradual turn to the west-northwest along with a decrease in forward speed is expected to occur beginning later tonight as the ridge weakens slightly. By late in the forecast period, a turn to the northwest should occur as Maria reaches a break in the ridge. The models are generally in good agreement on this scenario, but vary somewhat in how sharp of a turn to the right Marie makes later on in the forecast period. The latest NHC track forecast is little changed from the previous one, and lies near the various track consensus models. FORECAST POSITIONS AND MAX WINDS INIT 01/0900Z 14.8N 118.1W 80 KT 90 MPH 12H 01/1800Z 15.2N 120.2W 100 KT 115 MPH 24H 02/0600Z 16.0N 122.7W 115 KT 130 MPH 36H 02/1800Z 16.9N 125.0W 120 KT 140 MPH 48H 03/0600Z 18.0N 126.9W 120 KT 140 MPH 60H 03/1800Z 19.0N 128.5W 100 KT 115 MPH 72H 04/0600Z 19.8N 130.0W 85 KT 100 MPH 96H 05/0600Z 21.1N 132.8W 65 KT 75 MPH 120H 06/0600Z 23.0N 135.0W 45 KT 50 MPH $$ Forecaster Latto

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Hurricane Marie Forecast Discussion Number 8

2020-10-01 04:50:16| National Hurricane Center (East Pacific)

Issued at 800 PM PDT Wed Sep 30 2020 000 WTPZ43 KNHC 010250 TCDEP3 Hurricane Marie Discussion Number 8 NWS National Hurricane Center Miami FL EP182020 800 PM PDT Wed Sep 30 2020 Passive microwave satellite data and satellite intensity estimates indicate that Marie has undergone a brief intensity hiatus since the previous advisory. Date from the 2055Z AMSR and 2306Z SSMI microwave passes indicated that the earlier eye feature has eroded some and opened up on the east side due to dry air entrainment and modest easterly vertical wind shear of about 10 kt. The initial intensity is being held at 65 kt based on subjective Dvorak classifications of T4.0/65 kt from both TAFB and SAB, and UW-CIMSS objective intensity estimates of T4.1/67 kt and 62 kt from ADT and SATCON, respectively. The motion estimate is 280/14 kt. The latest NHC model guidance remains in excellent agreement through about 96 h on Marie moving west-northwestward toward a weakness in the subtropical ridge located to the north of the cyclone. Thereafter, there is considerable divergence in the guidance with the ECMWF and UKMET taking Marie more westward, while the GFS, HWRF, and HMON models take the hurricane northward into a break in the ridge; the latter scenario is preferred by the various simple and corrected consensus models. As a result, no significant changes were required to the previous forecast, and the new forecast track essentially lies down the model of the tightly packed consensus model envelope. Although the eyewall has eroded somewhat, the small inner-core wind field still appears to be intact based on low-level cloud features seen in 36-37 GHz satellite imagery. Once the narrow dry air intrusions mix out in about 6 hours or so, rapid intensification (RI) should resume and continue through 48 hours while the shear gradually decreases to near zero by then. By 60 hours and continuing through the remainder of the forecast period, cooler sea-surface temperatures, along with cold upwelling generated by Marie, should cause the hurricane to weaken, with rapid weakening likely beginning by 72 hours when significant southwesterly vertical wind shear kicks in ahead of a deep-layer trough that will be moving eastward out of the central Pacific. The new official intensity forecast is essentially identical to the previous NHC forecast, and lies along the extreme upper end of the intensity guidance, about midway between the Navy COAMPS-TC model (CTCI) and the NOAA-HCCA corrected-consensus model. FORECAST POSITIONS AND MAX WINDS INIT 01/0300Z 14.5N 116.5W 65 KT 75 MPH 12H 01/1200Z 14.7N 118.6W 80 KT 90 MPH 24H 02/0000Z 15.3N 121.3W 100 KT 115 MPH 36H 02/1200Z 16.2N 123.6W 115 KT 130 MPH 48H 03/0000Z 17.2N 125.6W 120 KT 140 MPH 60H 03/1200Z 18.2N 127.5W 100 KT 115 MPH 72H 04/0000Z 19.1N 129.1W 85 KT 100 MPH 96H 05/0000Z 20.7N 131.8W 65 KT 75 MPH 120H 06/0000Z 22.6N 134.3W 45 KT 50 MPH $$ Forecaster Stewart

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Hurricane Marie Forecast Discussion Number 7

2020-09-30 22:44:58| National Hurricane Center (East Pacific)

Issued at 200 PM PDT Wed Sep 30 2020 000 WTPZ43 KNHC 302044 TCDEP3 Hurricane Marie Discussion Number 7 NWS National Hurricane Center Miami FL EP182020 200 PM PDT Wed Sep 30 2020 Marie has continued to become better organized today, with a well-defined convective band that wraps more than completely around the cloud system center. This yields a Dvorak intensity estimate of at least 65 kt, and subjective and objective T-numbers from SAB and UW-CIMSS respectively also correspond to an intensity of 65 kt. Therefore, the system is being upgraded to a hurricane, which is the first for the month of September in this relatively quiet eastern North Pacific hurricane season. The vertical wind shear has decreased and is forecast to remain low for the next few days. This, combined with a moist low- to mid-tropospheric air mass and warm sea surface temperatures, should lead to an environment that is very conducive for strengthening. In fact, the SHIPS RI Index shows a significant probability of rapid intensification over the next 24 hours. Therefore, the official forecast calls for Marie to become a major hurricane tomorrow with additional strengthening during the succeeding day. This is close to the predictions from the two corrected consensus techniques, HCCA and FSSE. By 72 hours, Marie should have begun passing over progressively cooler waters, so a steady weakening trend is likely to be underway by that time. The motion continues just north of due west, or 275/14 kt. The track forecast reasoning hasn't changed much from the previous advisories. Over the next few days, the hurricane should be steered on a westward to west-northwestward course on the south side of a mid-level subtropical ridge. Right around the end of the forecast period, Marie should begin to turn more to the right in response to a weakness in the ridge. The official track forecast is similar to the previous one and lies between the simple and corrected dynamical consensus predictions. FORECAST POSITIONS AND MAX WINDS INIT 30/2100Z 14.3N 115.1W 65 KT 75 MPH 12H 01/0600Z 14.4N 117.3W 85 KT 100 MPH 24H 01/1800Z 14.8N 120.0W 100 KT 115 MPH 36H 02/0600Z 15.6N 122.5W 115 KT 130 MPH 48H 02/1800Z 16.6N 124.7W 120 KT 140 MPH 60H 03/0600Z 17.7N 126.7W 120 KT 140 MPH 72H 03/1800Z 18.6N 128.4W 100 KT 115 MPH 96H 04/1800Z 20.3N 131.4W 70 KT 80 MPH 120H 05/1800Z 21.8N 134.0W 50 KT 60 MPH $$ Forecaster Pasch

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