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Tropical Storm Mario Forecast Discussion Number 14

2019-09-20 22:46:50| National Hurricane Center (East Pacific)

Issued at 300 PM MDT Fri Sep 20 2019 000 WTPZ44 KNHC 202046 TCDEP4 Tropical Storm Mario Discussion Number 14 NWS National Hurricane Center Miami FL EP142019 300 PM MDT Fri Sep 20 2019 A resumption of northeasterly shear has caused the center of Mario to peak out to the northeast of its convective canopy. This is the second day in row that the low-level center of Mario has become exposed after it developed a low- to mid-level eye in microwave imagery the previous night. ASCAT data from shortly before 1800 UTC showed maximum winds around 50 kt, so the intensity estimate is still 55 kt, assuming a little undersampling has occurred. All of the intensity guidance indicates that Mario has already peaked and should only weaken from now on. Given how the last few nights have gone, I am not confident that Mario will weaken as quickly as the models suggest, but it does seem likely that steady weakening will begin by tomorrow afternoon, if not sooner. The tropical storm will reach some very cold water by 72 h, and it is forecast to become a remnant low at that time. The official intensity forecast is slightly lower than the previous one, but it is above most of the guidance for the first 72 h. The track forecast remains highly uncertain, especially beyond 24 h. The guidance spread is a little lower than it was before, but the run-to-run consistency is still quite low. In general, the models are calling for less binary interaction between Mario and Lorena, with Mario simply lifting northward to north-northeastward in Lorena's wake. As a result, Mario is now forecast by most of the models to move closer to the Baja California peninsula than it was before. The NHC track forecast has been adjusted substantially to the east beyond 24 h accordingly, and there remains a distinct chance that Mario will directly affect portions of the Baja California peninsula. FORECAST POSITIONS AND MAX WINDS INIT 20/2100Z 18.0N 110.0W 55 KT 65 MPH 12H 21/0600Z 18.7N 110.1W 55 KT 65 MPH 24H 21/1800Z 19.8N 110.6W 50 KT 60 MPH 36H 22/0600Z 21.0N 111.3W 40 KT 45 MPH 48H 22/1800Z 22.6N 112.3W 35 KT 40 MPH 72H 23/1800Z 25.3N 114.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 24/1800Z 26.5N 116.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 25/1800Z...DISSIPATED $$ Forecaster Zelinsky

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Tropical Storm Kiko Forecast Discussion Number 34

2019-09-20 22:45:53| National Hurricane Center (East Pacific)

Issued at 200 PM PDT Fri Sep 20 2019 000 WTPZ43 KNHC 202045 TCDEP3 Tropical Storm Kiko Discussion Number 34 NWS National Hurricane Center Miami FL EP132019 200 PM PDT Fri Sep 20 2019 Kiko hasn't changed much over the past 6 hours. Microwave imagery continues to show a fairly well-defined inner-core, but cloud tops have been warming during the past few hours. Satellite-based estimates continue to hover around 50 kt, and the estimated intensity is therefore held at that value. Kiko has turned to the northwest yet again, and should turn westward later today. There is no change in the forecast reasoning. Kiko will likely move on a wave-like path westward for the next several days, losing latitude as a mid-level ridge to the north amplifies, and gaining latitude as the ridge weakens. The only difference in the NHC forecast is that Kiko is forecast to move very slightly faster than it was before. It should be noted that there is still a decent amount of spread in the guidance regarding how quickly Kiko will move west even though the multi-model consensus, which is the basis for the NHC forecast, has not changed much. The tropical storm may have exhausted its opportunity to strengthen now that it has begun to turn back westward, and all of the reliable intensity guidance forecasts that Kiko will slowly weaken. The NHC forecast shows the same, but maintains Kiko as a tropical storm, still over the eastern North Pacific, through day 5. Kiko is a small tropical cyclone, and small short-term fluctuations in intensity are certainly possible during the next few days, but anticipating such fluctuations is beyond the current science of hurricane forecasting. FORECAST POSITIONS AND MAX WINDS INIT 20/2100Z 17.9N 130.8W 50 KT 60 MPH 12H 21/0600Z 18.2N 131.4W 50 KT 60 MPH 24H 21/1800Z 18.1N 132.3W 50 KT 60 MPH 36H 22/0600Z 17.5N 133.4W 45 KT 50 MPH 48H 22/1800Z 16.9N 134.4W 45 KT 50 MPH 72H 23/1800Z 16.5N 136.6W 45 KT 50 MPH 96H 24/1800Z 18.2N 137.5W 40 KT 45 MPH 120H 25/1800Z 18.5N 139.0W 40 KT 45 MPH $$ Forecaster Zelinsky

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Hurricane Jerry Forecast Discussion Number 13

2019-09-20 16:57:46| National Hurricane Center (Atlantic)

Issued at 1100 AM AST Fri Sep 20 2019 000 WTNT45 KNHC 201457 TCDAT5 Hurricane Jerry Discussion Number 13 NWS National Hurricane Center Miami FL AL102019 1100 AM AST Fri Sep 20 2019 Data from both NOAA and Air Force Reserve Hurricane Hunter aircraft indicate that Jerry is weakening quickly, and radar images from NOAA show no sign of the eyewall reported on the last mission. Maximum flight-level winds on the mission were about 78 kt, with SFMR values near 70 kt, and the central pressure has risen about 10 mb overnight. These observations also agree with the latest satellite imagery that shows a less organized cyclone, with the center on the far northwestern edge of a distorted central dense overcast. A blend of all these data gives an initial wind speed estimate of 75 kt. Jerry is moving about the same as before, west-northwestward at 15 kt. The hurricane should gradually bend to the right and slow down during the next few days while the cyclone is steered around the western periphery of a weakening subtropical ridge. The guidance is tightly packed on the forecast through Monday, and little change was made to the previous NHC prediction. At longer range, a mid-latitude trough interaction should turn the hurricane northward and northeastward, but the models are really struggling on how quickly this occurs. While yesterday much of the guidance had Jerry accelerating ahead of the trough, today's models have slowed everything down as the trough looks like it could weaken before fully recurving the cyclone. The new track forecast is considerably slower than the last one beyond 72 hours, about as much as continuity allows, and later forecasts could slow Jerry down even more. Northwesterly shear is forecast to persist near Jerry for the next day or two, and some weakening is expected. The intensity forecast is reduced from the previous one, and could be a bit too high in the short term given recent trends. In a few days, the aforementioned trough interaction is anticipated, but it is next to impossible to know at this lead time whether the trough will weaken or strengthen the cyclone, so no forecast change is made. It is a little tempting to raise the intensity by the end, given the recent weaker mid-latitude trough in the models, but there's just too much track uncertainty to mess with the intensity forecast at this time. Key Messages: 1. Although the core of Jerry is expected to move north of the northern Leeward Islands, heavy rainfall and flash floods are possible there today. FORECAST POSITIONS AND MAX WINDS INIT 20/1500Z 18.8N 60.3W 75 KT 85 MPH 12H 21/0000Z 19.6N 62.4W 70 KT 80 MPH 24H 21/1200Z 20.9N 64.7W 65 KT 75 MPH 36H 22/0000Z 22.3N 66.6W 60 KT 70 MPH 48H 22/1200Z 23.6N 68.0W 60 KT 70 MPH 72H 23/1200Z 26.5N 69.0W 65 KT 75 MPH 96H 24/1200Z 29.0N 67.5W 65 KT 75 MPH 120H 25/1200Z 33.0N 64.0W 65 KT 75 MPH $$ Forecaster Blake

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Tropical Storm Mario Forecast Discussion Number 13

2019-09-20 16:55:45| National Hurricane Center (East Pacific)

Issued at 900 AM MDT Fri Sep 20 2019 000 WTPZ44 KNHC 201455 TCDEP4 Tropical Storm Mario Discussion Number 13 NWS National Hurricane Center Miami FL EP142019 900 AM MDT Fri Sep 20 2019 Microwave imagery since the last advisory indicates that Mario has been able to maintain its low-level structure, but deep convection is mostly displaced to the southwest of the cyclone's surface center. This may be a sign that northeasterly shear has again increased across Mario, at least for the moment. The intensity estimate is still 55 kt based on Dvorak current intensity estimates from TAFB and SAB, but objective values are lower. Almost no change was made to the NHC intensity forecast. SHIPS diagnostics from the GFS and ECMWF indicate that substantial northeasterly shear will continue to affect Mario for the next couple of days, and by the time the shear relaxes early next week, the cyclone will have reached much cooler waters. Given that Mario is in better shape than it was a day ago, some slight strengthening is still shown in the short-term forecast, but only the GFS explicitly forecasts Mario to reach hurricane strength. Nearly all of the dynamical models forecast that Mario will lose its convection and become a remnant low by 96 h or sooner, and this is reflected in the NHC forecast. The track forecast is very low confidence, evidenced by the fact that the deterministic GFS and ECMWF are both outliers from their respective ensembles run at the same time. In fact, both models are outside of their associated guidance envelope and show Mario getting very near the southern tip of the Baja California peninsula in a couple of days. There is still considerable uncertainty as to how much Mario and Lorena will interact during the next 2 or 3 days. The NHC forecast continues to keep the two systems separate, showing both systems moving generally northwestward in tandem at 48 h and beyond. However, given the close proximity of the two cyclones, a merger can not be ruled out. The NHC forecast has been shifted to the right of the previous forecast, and lies near the middle of the GFS and ECMWF ensemble envelopes. Significant changes may still be required to the track forecast later today, and there is still a chance that Mario could directly affect portions of the Baja California peninsula. FORECAST POSITIONS AND MAX WINDS INIT 20/1500Z 17.9N 110.1W 55 KT 65 MPH 12H 21/0000Z 18.6N 110.0W 60 KT 70 MPH 24H 21/1200Z 19.8N 110.7W 55 KT 65 MPH 36H 22/0000Z 21.1N 112.1W 50 KT 60 MPH 48H 22/1200Z 22.3N 113.8W 45 KT 50 MPH 72H 23/1200Z 25.0N 116.6W 30 KT 35 MPH 96H 24/1200Z 26.0N 118.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 25/1200Z 25.0N 120.5W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Zelinsky

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Hurricane Lorena Forecast Discussion Number 13

2019-09-20 16:52:44| National Hurricane Center (East Pacific)

Issued at 900 AM MDT Fri Sep 20 2019 000 WTPZ45 KNHC 201452 TCDEP5 Hurricane Lorena Discussion Number 13 NWS National Hurricane Center Miami FL EP152019 900 AM MDT Fri Sep 20 2019 Microwave data overnight showed that an eye feature was trying to form, and this feature became really distinct on the 1059 UTC SSMIS image. A hint of an eye is becoming apparent on visible images at this time. An average of subjective and objective T-numbers yields an initial intensity of 65 kt. Lorena is moving over very warm waters, and this could help the cyclone to strengthen some during the next 12 hours while the cyclone is near or over the southern portion of the Baja California peninsula. After that time, once the cyclone reaches the cooler waters just west of the peninsula, weakening should the begin. In addition, the chances of Lorena becoming absorbed by Tropical Storm Mario in about 48 hours have increased as indicated by some global models. Regardless of the possible interaction scenario, dissipation of Lorena will occur in less than 4 days. Lorena has been moving very slowly toward the west or 280 degrees at 2 kt. The cyclone is being steered by the flow around a subtropical ridge over Mexico, and the circulation of Tropical Storm Mario to the south. Lorena should turn a little more to the west-northwest around the ridge with some increase in forward speed. Most of the track guidance indicate that this turn should occur well to the west of the Baja California peninsula. The NHC forecast is a little bit to the right of the previous one, and is in between the multi-model consensus and the corrected consensus HCCA. Key Messages: 1. Lorena is expected to bring heavy rainfall to the far southern Baja California Sur today into Saturday, with flash flooding possible. 2. Lorena is forecast to bring hurricane-force winds to a portion of the southern Baja California peninsula today, where a Hurricane Warning is in effect. Preparations to protect life and property should be rushed to completion. FORECAST POSITIONS AND MAX WINDS INIT 20/1500Z 22.7N 109.0W 65 KT 75 MPH 12H 21/0000Z 22.8N 110.2W 70 KT 80 MPH 24H 21/1200Z 23.3N 111.7W 70 KT 80 MPH 36H 22/0000Z 23.7N 112.6W 60 KT 70 MPH 48H 22/1200Z 24.4N 113.8W 50 KT 60 MPH 72H 23/1200Z 26.5N 116.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 24/1200Z...DISSIPATED $$ Forecaster Avila

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