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Post-Tropical Cyclone HERMINE Forecast Discussion Number 33
2016-09-05 17:30:54| National Hurricane Center (Atlantic)
Issued at 1100 AM AST MON SEP 05 2016 000 WTNT44 KNHC 051530 TCDAT4 POST-TROPICAL CYCLONE HERMINE DISCUSSION NUMBER 33...CORRECTED NWS NATIONAL HURRICANE CENTER MIAMI FL AL092016 1100 AM AST MON SEP 05 2016 Corrected for initial motion in second paragraph Hermine continues to exhibit a non-tropical cloud pattern with a broad curved band of showers to the north of the center. High-resolution visible images show multiple low-level swirls rotating around the broad center of the cyclone. An Air Force reconnaissance plane found highest unflagged SFMR-observed surface winds of 52 kt, and highest 850 mb flight-level winds were 69 kt, both north of the center. The initial intensity estimate remains 60 kt. Although Hermine is currently over rather warm waters, the system should be passing over cooler SSTs by early Tuesday and this should result in a weakening trend. The official intensity forecast is consistent with the trend depicted by the global models. These models, especially the ECMWF, suggest that the system will open up to a trough by the end of the forecast period and this is also reflected in the official forecast. The center is not particularly well defined, and using a mean center position from the multiple swirls leads to a motion estimate of 325/5 kt, which is rather uncertain. Hermine is in a weak steering environment. A narrow mid-level ridge to the north of the cyclone should induce a continued northwestward motion at a slow forward speed during the next 24 hours or so. As this ridge breaks down by Tuesday night, the system should turn northward. Later in the forecast period, the mid-latitude westerlies should carry Hermine off to the east-northeast and northeast. The track forecast has been shifted west of the previous NHC track, but lies a little to the east of the multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 38.8N 68.8W 60 KT 70 MPH...POST-TROPICAL 12H 06/0000Z 39.2N 69.5W 60 KT 70 MPH...POST-TROPICAL 24H 06/1200Z 39.7N 70.5W 55 KT 65 MPH...POST-TROPICAL 36H 07/0000Z 40.0N 70.7W 45 KT 50 MPH...POST-TROPICAL 48H 07/1200Z 40.5N 70.5W 40 KT 45 MPH...POST-TROPICAL 72H 08/1200Z 41.0N 69.0W 35 KT 40 MPH...POST-TROPICAL 96H 09/1200Z 44.5N 62.0W 30 KT 35 MPH...POST-TROPICAL 120H 10/1200Z...DISSIPATED $$ Forecaster Pasch
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Tropical Storm NEWTON Forecast Discussion Number 4
2016-09-05 17:07:50| National Hurricane Center (East Pacific)
Issued at 900 AM MDT MON SEP 05 2016 000 WTPZ45 KNHC 051507 TCDEP5 TROPICAL STORM NEWTON DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL EP152016 900 AM MDT MON SEP 05 2016 Newton's cloud pattern is characterized by a large mass of very cold-topped convection, with the center located underneath this formative central dense overcast on the north side. A ship earlier reported 50 kt, and although the ship had somewhat of a high bias, the 12z sounding from Manzanillo reported an 850 mb wind of 65 kt. A typical wind reduction over the water would suggest about 50 kt at the surface, and since the sounding supports the ship observation, the initial intensity is set to 50 kt. The center location of Newton has been difficult to determine, and hence the initial motion estimate is an uncertain 330/11. Newton is currently being steered northwestward on the southwest side of a mid-level ridge over the United States Lower Mississippi Valley. The cyclone should be drawn north-northwestward and then northward in 36 to 48 hours between this feature and a trough of low pressure gradually lifting out over the western United States. The official NHC track forecast is somewhat faster and slightly to the left of the previous one and near the multi-model consensus. It lies on the western side of the guidance, but with only the ECMWF and UKMET models to the left. Newton is expected to remain in a very moist environment with generally light northeasterly shear during the next 24 hours. These factors, along with the cyclone's passage over sea surface temperatures above 29 deg C, should allow for steady intensification until the center reaches the coast. The only obvious obstacle to strengthening is Newton's broad structure, but indications are that the cyclone may be in the process of consolidating. It should be noted that the SHIPS RI Index indicates a 60-70 percent chance of an intensity increase of around 25 kt during the next 24 hours. The NHC intensity forecast now calls for Newton to become a hurricane prior to landfall, which is a little above the multi-model consensus. Weakening is likely when Newton moves across the Baja California peninsula, but little change in strength is expected as southwesterly shear begins to increase over the Gulf of California in 36 to 48 hours. Newton is expected to be a large hurricane at landfall, and hazards are likely to affect a large portion of Baja California and northwestern Mexico. In addition, moisture associated with the remnants of Newton could cause heavy rains and localized flash flooding over parts of Arizona and New Mexico. Based on the new intensity and track forecasts, the government of Mexico has made a variety of changes to the watches and warnings. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 19.1N 107.0W 50 KT 60 MPH 12H 06/0000Z 20.6N 108.4W 60 KT 70 MPH 24H 06/1200Z 22.8N 110.0W 70 KT 80 MPH 36H 07/0000Z 25.3N 111.3W 60 KT 70 MPH 48H 07/1200Z 28.1N 111.6W 50 KT 60 MPH...INLAND 72H 08/1200Z 33.5N 110.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 09/1200Z...DISSIPATED $$ Forecaster Kimberlain
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Tropical Storm NEWTON Forecast Discussion Number 4
2016-09-05 16:59:32| National Hurricane Center (East Pacific)
Issued at 900 AM MDT MON SEP 05 2016 000 WTPZ45 KNHC 051459 TCDEP5 TROPICAL STORM NEWTON DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL EP152016 900 AM MDT MON SEP 05 2016 NEWTON'S CLOUD PATTERN IS CHARACTERIZED BY LARGE MASS OF VERY COLD-TOPPED CONVECTION WITH THE CENTER LOCATED UNDERNEATH THIS FORMATIVE CENTRAL DENSE OVERCAST ON THE NORTH SIDE. A SHIP EARLIER REPORTED 50 KT, AND ALTHOUGH THIS SHIP HAD SOMEWHAT OF A HIGH BIAS, THE 12Z SOUNDING FROM MANZANILLO REPORTED AN 850 MB WIND OF 65 KT. A TYPICAL WIND REDUCTION OVER THE WATER WOULD SUGGEST ABOUT 50 KT AT THE SURFACE, AND SINCE THE SOUNDING SUPPORTS THE SHIP OBSERVATION, THE INITIAL INTENSITY IS SET TO 50 KT. THE CENTER LOCATION OF NEWTON HAS BEEN DIFFICULT TO DETERMINE, AND HENCE THE INITIAL MOTION IS AN UNCERTAIN 330/11. NEWTON IS CURRENTLY BEING STEERED NORTHWESTWARD ON THE SOUTHWEST SIDE OF A MID-LEVEL RIDGE OVER THE UNITED STATES LOWER MISSISSIPPI VALLEY. THE CYCLONE SHOULD BE DRAWN NORTH-NORTHWESTWARD AND THEN NORTHWARD IN 36 TO 48 HOURS BETWEEN THIS FEATURE AND A TROUGH OF LOW PRESSURE GRADUALLY LIFTING OUT OVER THE WESTERN UNITED STATES. THE OFFICIAL NHC TRACK FORECAST IS SOMEWHAT FASTER AND SLIGHTLY TO THE LEFT OF THE PREVIOUS ONE AND NEAR THE MULTI-MODEL CONSENSUS. IT LIES ON THE WESTERN SIDE OF THE GUIDANCE, BUT WITH ONLY THE ECMWF AND UKMET MODELS TO LEFT. NEWTON IS EXPECTED TO REMAIN IN A VERY MOIST ENVIRONMENT WITH GENERALLY LIGHT NORTHEASTERLY SHEAR DURING THE NEXT 24 HOURS. THESE FACTORS, ALONG WITH THE CYCLONE'S PASSAGE OVER SEA SURFACE TEMPERATURES ABOVE 29 DEG C, SHOULD ALLOW FOR STEADY INTENSIFICATION UNTIL THE CENTER REACHES THE COAST. THE ONLY OBVIOUS OBSTACLE TO STRENGTHENING IS NEWTON'S BROAD STRUCTURE, BUT INDICATIONS ARE THAT THE CYCLONE MAY BE IN THE PROCESS OF CONSOLIDATING. IT SHOULD BE NOTED THAT THE SHIPS RI INDEX INDICATES A 60-70 CHANCE OF AN INTENSITY INCREASE OF AROUND 25 KT DURING THE NEXT 24 HOURS. THE NHC INTENSITY FORECAST NOW CALLS FOR NEWTON TO BECOME A HURRICANE PRIOR TO LANDFALL, WHICH IS LITTLE ABOVE THE MULTI-MODEL CONSENSUS. WEAKENING IS LIKELY WHEN NEWTON MOVES ACROSS THE BAJA CALIFORNIA PENINSULA, BUT LITTLE CHANGE IN STRENGTH IS EXPECTED AS THE SOUTHWESTERLY SHEAR BEGINS TO INCREASE OVER THE GULF OF CALIFORNIA IN 36 TO 48 HOURS. NEWTON IS EXPECTED TO BE A LARGE HURRICANE AT LANDFALL, AND HAZARDS ARE LIKELY TO AFFECT A LARGE PORTION OF BAJA CALIFORNIA AND NORTHWESTERN MEXICO. IN ADDITION, MOISTURE ASSOCIATED WITH THE REMNANTS OF NEWTON COULD CAUSE HEAVY RAINS AND LOCALIZED FLASH FLOODING OVER PARTS OF ARIZONA AND NEW MEXICO. BASED ON THE NEW INTENSITY AND TRACK FORECASTS, THE GOVERNMENT OF MEXICO HAS MADE A VARIETY OF CHANGES TO THE WATCHES AND WARNINGS. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 19.1N 107.0W 50 KT 60 MPH 12H 06/0000Z 20.6N 108.4W 60 KT 70 MPH 24H 06/1200Z 22.8N 110.0W 70 KT 80 MPH 36H 07/0000Z 25.3N 111.3W 60 KT 70 MPH 48H 07/1200Z 28.1N 111.6W 50 KT 60 MPH...INLAND 72H 08/1200Z 33.5N 110.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 09/1200Z...DISSIPATED $$ Forecaster Kimberlain
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Post-Tropical Cyclone HERMINE Forecast Discussion Number 33
2016-09-05 16:41:32| National Hurricane Center (Atlantic)
Issued at 1100 AM AST MON SEP 05 2016 000 WTNT44 KNHC 051441 TCDAT4 POST-TROPICAL CYCLONE HERMINE DISCUSSION NUMBER 33 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092016 1100 AM AST MON SEP 05 2016 Hermine continues to exhibit a non-tropical cloud pattern with a broad curved band of showers to the north of the center. High-resolution visible images show multiple low-level swirls rotating around the broad center of the cyclone. An Air Force reconnaissance plane found highest unflagged SFMR-observed surface winds of 52 kt, and highest 850 mb flight-level winds were 69 kt, both north of the center. The initial intensity estimate remains 60 kt. Although Hermine is currently over rather warm waters, the system should be passing over cooler SSTs by early Tuesday and this should result in a weakening trend. The official intensity forecast is consistent with the trend depicted by the global models. These models, especially the ECMWF, suggest that the system will open up to a trough by the end of the forecast period and this is also reflected in the official forecast. The center is not particularly well defined, and using a mean center position from the multiple swirls leads to a motion estimate of 030/5 kt, which is rather uncertain. Hermine is in a weak steering environment. A narrow mid-level ridge to the north of the cyclone should induce a continued northwestward motion at a slow forward speed during the next 24 hours or so. As this ridge breaks down by Tuesday night, the system should turn northward. Later in the forecast period, the mid-latitude westerlies should carry Hermine off to the east-northeast and northeast. The track forecast has been shifted west of the previous NHC track, but lies a little to the east of the multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 38.8N 68.8W 60 KT 70 MPH...POST-TROPICAL 12H 06/0000Z 39.2N 69.5W 60 KT 70 MPH...POST-TROPICAL 24H 06/1200Z 39.7N 70.5W 55 KT 65 MPH...POST-TROPICAL 36H 07/0000Z 40.0N 70.7W 45 KT 50 MPH...POST-TROPICAL 48H 07/1200Z 40.5N 70.5W 40 KT 45 MPH...POST-TROPICAL 72H 08/1200Z 41.0N 69.0W 35 KT 40 MPH...POST-TROPICAL 96H 09/1200Z 44.5N 62.0W 30 KT 35 MPH...POST-TROPICAL 120H 10/1200Z...DISSIPATED $$ Forecaster Pasch
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Tropical Storm NEWTON Forecast Discussion Number 3
2016-09-05 10:57:49| National Hurricane Center (East Pacific)
Issued at 300 AM MDT MON SEP 05 2016 000 WTPZ45 KNHC 050857 TCDEP5 TROPICAL STORM NEWTON DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL EP152016 300 AM MDT MON SEP 05 2016 Newton appears to be gradually strengthening. The tropical storm is producing a large area of deep convection, which is a little better organized than it was several hours ago. The Dvorak classifications from TAFB and SAB were 2.5/35 kt, and automated values from CIMSS at the University of Wisconsin are close to 3.0/45 kt. Based on these data, the initial wind speed estimate is increased to 40 kt. The low-level center has been challenging to locate overnight, but it appears that Newton is moving north-northwestward at about 9 kt. The tropical storm is forecast to move northwestward at a faster pace during the next day or two while it tracks along the southwestern periphery of a mid-level ridge centered over the south-central United States. A turn to the north is expected beyond a couple of days when Newton rounds the ridge and moves into a pronounced weakness. The track guidance has shifted a little to the west this cycle, and the NHC forecast has been nudged in that direction. The new NHC forecast brings the center of Newton very close to the extreme southern Baja California peninsula in 24 to 36 hours. Low shear, a moist environment, and very warm water should allow Newton to steadily strengthen until it reaches the Baja California peninsula. In fact, rapid intensification is a possibility as the SHIPS Rapid Intensification Index shows a 40 percent chance of a 30-kt increase in the winds during the next 24 hours. Based on the expected conducive environment, the NHC intensity forecast remains near the high end of the guidance during the next day or two. After Newton passes the Baja peninsula, weakening should occur due to land interaction and an increase in vertical wind shear. Based on the latest forecast, the Government of Mexico has extended the watches and warnings northward along the Baja California coastlines and the west coast of mainland Mexico. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 17.9N 106.1W 40 KT 45 MPH 12H 05/1800Z 19.2N 107.4W 50 KT 60 MPH 24H 06/0600Z 21.3N 109.0W 60 KT 70 MPH 36H 06/1800Z 23.3N 110.3W 60 KT 70 MPH...NEAR THE COAST 48H 07/0600Z 25.9N 111.2W 55 KT 65 MPH...NEAR THE COAST 72H 08/0600Z 31.2N 111.1W 30 KT 35 MPH...INLAND 96H 09/0600Z...DISSIPATED $$ Forecaster Cangialosi
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