Home › forecast
 

Keywords :   


Tag: forecast

Tropical Storm Isaias Forecast Discussion Number 26

2020-08-03 16:57:19| National Hurricane Center (Atlantic)

Issued at 1100 AM EDT Mon Aug 03 2020 000 WTNT44 KNHC 031457 TCDAT4 Tropical Storm Isaias Discussion Number 26 NWS National Hurricane Center Miami FL AL092020 1100 AM EDT Mon Aug 03 2020 Isaias continues to undergo strong bursting and then weakening convective phases, with the cyclone currently in the latter mode. Satellite and radar data indicate that Isaias' convective organization has become a little disheveled since the previous advisory, but this is to be expected since the tropical cyclone has been undergoing bursting periods about every 8 hours or so beginning overnight around 0600-0900Z. Thus, the system is due for another re-organization phase shortly if it holds true to form. That may already be underway based on recent radar and recon data showing a slight eastward shift in the center position. The highest 700-mb flight-level wind observed has been 63 kt, which reduces to about a 57-kt surface wind. Jacksonville Doppler radar velocities north and north-northwest of the center have been around 60 kt at 9,000 ft, which equals about 54 kt surface winds. The initial intensity will be held at 60 kt, perhaps a little generously, for this advisory despite the recent rise in the central pressure to around 998 mb. Isaias is still moving northward but a little faster at 360/11 kt. The track forecast reasoning remains essentially the same as the previous few advisories, with Isaias expected to gradually turn toward the north-northeast later today and begin to accelerate by this evening. The latest NHC model guidance is more tightly packed about the previous advisory track, so only minor tweaks were required. The new NHC track forecast lies very close to a blend of the multi-model consensus aids TVCA, GFEX, TVCX, and NOAA-HCCA. Current westerly vertical wind shear of 20-25 kt is expected to decrease somewhat during the next 12 h and also become more southwesterly, which will be in better alignment with Isaias' forward motion vector. The decrease in the shear should result in less tilt to the cyclone, allowing Isaias to strengthen and regain hurricane status just before making landfall, and most of the intensity guidance shows a 60-65 kt system at that time. After landfall, Isaias is forecast to only slowly weaken due to interaction with an unusually strong winter-type jetstream that will be possessing winds of 100-120 kt. Expected strong baroclinic forcing will keep Isaias' circulation intact and also produce very strong wind gusts along the Mid-Atlantic states tomorrow. As a result, the gust factors at 24-48 h have been increased above the standard 20 percent in the Forecast/Advisory (TCMAT4). The cyclone is forecast to be absorbed by a larger extratropical low over Canada in 3-4 days. Key Messages: 1. There is the danger of life-threatening storm surge inundation along portions of the immediate coastline and adjacent waterways of northeastern South Carolina and the North Carolina coast in the Storm Surge Warning area. Residents in these areas should follow advice given by local emergency officials. 2. Isaias is forecast to regain hurricane strength before it reaches the coast of northeastern South Carolina and southern North Carolina, and hurricane conditions are expected in the Hurricane Warning area by this evening. Preparations should be rushed to completion. 3. Isaias is expected to bring widespread sustained tropical storm force winds and wind gusts to hurricane force to the mid-Atlantic coast Tuesday, which could cause tree damage and power outages. Tropical storm conditions are expected to reach southern New England on late Tuesday and are possible along the northern New England coast Tuesday night and early Wednesday. 4. Heavy rainfall will result in flash and urban flooding, some of which may be significant in the eastern Carolinas and the mid-Atlantic, through Tuesday night near the path of Isaias up the East Coast of the United States. Widespread minor to moderate river flooding is possible across portions of the Carolinas and the Mid-Atlantic. FORECAST POSITIONS AND MAX WINDS INIT 03/1500Z 30.7N 80.1W 60 KT 70 MPH 12H 04/0000Z 33.1N 79.2W 65 KT 75 MPH 24H 04/1200Z 37.2N 77.0W 55 KT 65 MPH...INLAND 36H 05/0000Z 42.0N 73.8W 50 KT 60 MPH...INLAND 48H 05/1200Z 46.7N 70.2W 35 KT 40 MPH...INLAND 60H 06/0000Z 50.2N 67.2W 30 KT 35 MPH...POST-TROP/EXTRATROP 72H 06/1200Z 53.5N 64.2W 25 KT 30 MPH...POST-TROP/EXTRATROP 96H 07/1200Z...DISSIPATED $$ Forecaster Stewart

Tags: number discussion storm tropical

 

Tropical Storm Isaias Forecast Advisory Number 26

2020-08-03 16:51:54| National Hurricane Center (Atlantic)

Issued at 1500 UTC MON AUG 03 2020 000 WTNT24 KNHC 031451 TCMAT4 TROPICAL STORM ISAIAS FORECAST/ADVISORY NUMBER 26 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092020 1500 UTC MON AUG 03 2020 CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY... A STORM SURGE WARNING HAS BEEN ISSUED FOR PORTIONS OF THE PAMLICO AND ALBEMARLE SOUNDS...INCLUDING THE NEUSE AND PAMLICO RIVERS... AND FOR THE NORTH CAROLINA OUTER BANKS FORM OREGON INLET TO THE NORTH CAROLINA/VIRGINIA BORDER. THE TROPICAL STORM WARNING HAS BEEN EXTENDED NORTHWARD TO THE MOUTH OF THE MERRIMACK RIVER...INCLUDING MARTHA'S VINEYARD...NANTUCKET... AND BLOCK ISLAND. THE TROPICAL STORM WATCH FOR THE REMAINDER OF THE CHESAPEAKE BAY AND THE TIDAL POTOMAC RIVER NORTH OF COBB ISLAND HAS BEEN CHANGED TO A TROPICAL STORM WARNING. THE TROPICAL STORM WATCH HAS BEEN EXTENDED NORTHWARD TO EASTPORT MAINE. THE TROPICAL STORM WARNING HAS BEEN DISCONTINUED SOUTH OF ALTAMAHA SOUND. SUMMARY OF WATCHES AND WARNINGS IN EFFECT... A STORM SURGE WARNING IS IN EFFECT FOR... * EDISTO BEACH SOUTH CAROLINA TO CAPE FEAR NORTH CAROLINA * PAMLICO AND ALBEMARLE SOUNDS, INCLUDING THE NEUSE AND PAMLICO RIVERS * OREGON INLET NORTH CAROLINA TO THE NORTH CAROLINA/VIRGINIA BORDER A STORM SURGE WATCH IS IN EFFECT FOR... * CAPE FEAR TO OREGON INLET NORTH CAROLINA A HURRICANE WARNING IS IN EFFECT FOR... * SOUTH SANTEE RIVER SOUTH CAROLINA TO SURF CITY NORTH CAROLINA A TROPICAL STORM WARNING IS IN EFFECT FOR... * ALTAMAHA SOUND GEORGIA TO SOUTH SANTEE RIVER SOUTH CAROLINA * NORTH OF SURF CITY NORTH CAROLINA TO THE MOUTH OF THE MERRIMACK RIVER * PAMLICO AND ALBEMARLE SOUNDS * CHESAPEAKE BAY * TIDAL POTOMAC RIVER * DELAWARE BAY * LONG ISLAND AND LONG ISLAND SOUND * MARTHA'S VINEYARD...NANTUCKET...AND BLOCK ISLAND A TROPICAL STORM WATCH IS IN EFFECT FOR... * MOUTH OF THE MERRIMACK RIVER TO EASTPORT MAINE INTERESTS ELSEWHERE ALONG THE NORTHEAST COAST OF THE UNITED STATES SHOULD MONITOR THE PROGRESS OF ISAIAS. ADDITIONAL WATCHES OR WARNINGS MAY BE REQUIRED LATER TODAY. A STORM SURGE WARNING MEANS THERE IS A DANGER OF LIFE-THREATENING INUNDATION...FROM RISING WATER MOVING INLAND FROM THE COASTLINE IN THE INDICATED LOCATIONS. FOR A DEPICTION OF AREAS AT RISK...PLEASE SEE THE NATIONAL WEATHER SERVICE STORM SURGE WATCH/WARNING GRAPHIC AT HURRICANES.GOV. THIS IS A LIFE-THREATENING SITUATION. PERSONS LOCATED WITHIN THESE AREAS SHOULD TAKE ALL NECESSARY ACTIONS TO PROTECT LIFE AND PROPERTY FROM RISING WATER AND THE POTENTIAL FOR OTHER DANGEROUS CONDITIONS. PROMPTLY FOLLOW EVACUATION AND OTHER INSTRUCTIONS FROM LOCAL OFFICIALS. A STORM SURGE WATCH MEANS THERE IS A POSSIBILITY OF LIFE- THREATENING INUNDATION FROM RISING WATER MOVING INLAND FROM THE COASTLINE IN THE INDICATED LOCATIONS. A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA...IN THIS CASE WITHIN 12 HOURS. PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO COMPLETION. A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA...GENERALLY WITHIN 36 HOURS. A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS. TROPICAL STORM CENTER LOCATED NEAR 30.7N 80.1W AT 03/1500Z POSITION ACCURATE WITHIN 20 NM PRESENT MOVEMENT TOWARD THE NORTH OR 360 DEGREES AT 11 KT ESTIMATED MINIMUM CENTRAL PRESSURE 998 MB MAX SUSTAINED WINDS 60 KT WITH GUSTS TO 75 KT. 50 KT....... 50NE 50SE 0SW 20NW. 34 KT.......100NE 110SE 0SW 60NW. 12 FT SEAS..150NE 120SE 60SW 90NW. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 30.7N 80.1W AT 03/1500Z AT 03/1200Z CENTER WAS LOCATED NEAR 30.2N 80.1W FORECAST VALID 04/0000Z 33.1N 79.2W MAX WIND 65 KT...GUSTS 80 KT. 64 KT... 25NE 25SE 0SW 0NW. 50 KT... 50NE 50SE 0SW 20NW. 34 KT...100NE 120SE 0SW 60NW. FORECAST VALID 04/1200Z 37.2N 77.0W...INLAND MAX WIND 55 KT...GUSTS 70 KT. 50 KT... 50NE 50SE 0SW 20NW. 34 KT...110NE 140SE 0SW 60NW. FORECAST VALID 05/0000Z 42.0N 73.8W...INLAND MAX WIND 50 KT...GUSTS 65 KT. 50 KT... 0NE 70SE 0SW 0NW. 34 KT...120NE 150SE 0SW 40NW. FORECAST VALID 05/1200Z 46.7N 70.2W...INLAND MAX WIND 35 KT...GUSTS 50 KT. 34 KT... 0NE 170SE 0SW 0NW. FORECAST VALID 06/0000Z 50.2N 67.2W...POST-TROP/EXTRATROP MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 06/1200Z 53.5N 64.2W...POST-TROP/EXTRATROP MAX WIND 25 KT...GUSTS 35 KT. EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM ON DAY 4 AND 175 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY OUTLOOK VALID 07/1200Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 30.7N 80.1W INTERMEDIATE PUBLIC ADVISORY...WTNT34 KNHC/MIATCPAT4...AT 03/1800Z NEXT ADVISORY AT 03/2100Z $$ FORECASTER STEWART

Tags: number storm advisory tropical

 
 

Tropical Storm Isaias Forecast Discussion Number 25

2020-08-03 10:56:48| National Hurricane Center (Atlantic)

Issued at 500 AM EDT Mon Aug 03 2020 000 WTNT44 KNHC 030856 TCDAT4 Tropical Storm Isaias Discussion Number 25 NWS National Hurricane Center Miami FL AL092020 500 AM EDT Mon Aug 03 2020 Isaias continues to produce an area of vigorous convection near and to the northeast of its low-level center. Overnight radar data from Melbourne and Jacksonville have shown a transient mid-level eye feature that is located northeast of the low-level center. The earlier Air Force Reserve Hurricane Hunter aircraft flew near that feature before departing the storm and found 700-mb flight-level winds of 71 kt, with the highest SFMR winds still around 60 kt, which is the basis for the initial wind speed for this advisory. An Air Force Reserve and NOAA Hurricane Hunter aircraft will be investigating Isaias within the next several hours. The vertical wind shear that has been plaguing Isaias is forecast to abate slightly today as the storm turns north-northeastward. All of the intensity models shows some slight strengthening during the next 12 hours, and the global models also indicate some deepening. As a result, the updated NHC intensity forecast calls for Isaias to regain hurricane status before the system moves over the coast of the Carolinas. The new intensity forecast has necessitated the issuance of a hurricane warning for a portion of the coasts of northern South Carolina and southern North Carolina. After landfall, Isaias is forecast to gradually weaken, but given the fast forward motion of the storm, strong winds are expected to spread northward along the coast of the Mid-Atlantic and Northeast United States. The cyclone is forecast to be absorbed by a larger extratropical low over Canada in 3-4 days. Isaias is moving northward or 355/8 kt. The track forecast reasoning remains the same as before. The tropical storm is expected to accelerate north-northeastward to northeastward ahead of a large mid-level trough over the eastern United States during the next couple of days. The dynamical models are in good agreement except for some slight differences in the forward speed of Isaias. The NHC track forecast is near the multi-model consensus aids, which have once again trended slightly faster. Key Messages: 1. There is the danger of life-threatening storm surge inundation along portions of the immediate coastline and adjacent waterways of northeastern South Carolina and southern North Carolina. Life-threatening storm surge is possible along the North Carolina coast from Cape Fear to Duck. Residents in these areas should follow advice given by local emergency officials. 2. Isaias is forecast to regain hurricane strength before it reaches the coast of northeastern South Carolina and southern North Carolina, and hurricane conditions are expected in the Hurricane Warning by this evening. Preparations should be rushed to completion. 3. Tropical storm conditions are expected to spread northward within the Tropical Storm Warning area from Florida to portions of southern New England through Tuesday afternoon. Tropical storm conditions are possible across other portions of New England within the Tropical Storm Watch area by early Wednesday. Additional watches or warnings may be required later today. 4. Heavy rainfall will result in flash and urban flooding, some of which may be significant in the eastern Carolinas and the mid-Atlantic, through midweek along and near the path of Isaias across the East Coast of the United States. Widespread minor to moderate river flooding is possible across portions of the Carolinas and the mid-Atlantic. FORECAST POSITIONS AND MAX WINDS INIT 03/0900Z 29.7N 79.9W 60 KT 70 MPH 12H 03/1800Z 31.3N 79.6W 65 KT 75 MPH 24H 04/0600Z 34.8N 78.1W 60 KT 70 MPH...INLAND 36H 04/1800Z 39.4N 75.2W 55 KT 65 MPH...INLAND 48H 05/0600Z 44.4N 71.5W 35 KT 40 MPH...INLAND 60H 05/1800Z 48.6N 68.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 72H 06/0600Z 52.0N 65.0W 25 KT 30 MPH...POST-TROP/EXTRATROP 96H 07/0600Z...DISSIPATED $$ Forecaster Brown/Berg

Tags: number discussion storm tropical

 

Tropical Storm Isaias Forecast Advisory Number 25

2020-08-03 10:55:49| National Hurricane Center (Atlantic)

Issued at 0900 UTC MON AUG 03 2020 000 WTNT24 KNHC 030855 TCMAT4 TROPICAL STORM ISAIAS FORECAST/ADVISORY NUMBER 25 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092020 0900 UTC MON AUG 03 2020 CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY... A HURRICANE WARNING HAS BEEN ISSUED FROM SOUTH SANTEE RIVER SOUTH CAROLINA TO SURF CITY NORTH CAROLINA. THE TROPICAL STORM WARNING HAS BEEN EXTENDED NORTHWARD TO WEST OF WATCH HILL RHODE ISLAND...INCLUDING THE TIDAL POTOMAC SOUTH OF COBB ISLAND...CHESAPEAKE BAY SOUTH OF NORTH BEACH...DELAWARE BAY... LONG ISLAND...AND LONG ISLAND SOUND. THE TROPICAL STORM WATCH HAS BEEN EXTENDED NORTHWARD TO STONINGTON... MAINE...INCLUDING MARTHA'S VINEYARD...NANTUCKET...AND BLOCK ISLAND. THE TROPICAL STORM WARNING HAS BEEN DISCONTINUED SOUTH OF THE FLAGLER/VOLUSIA COUNTY LINE. SUMMARY OF WATCHES AND WARNINGS IN EFFECT... A STORM SURGE WARNING IS IN EFFECT FOR... * EDISTO BEACH SOUTH CAROLINA TO CAPE FEAR NORTH CAROLINA A STORM SURGE WATCH IS IN EFFECT FOR... * CAPE FEAR TO DUCK NORTH CAROLINA * PAMLICO AND ALBEMARLE SOUNDS A HURRICANE WARNING IS IN EFFECT FOR... * SOUTH SANTEE RIVER SOUTH CAROLINA TO SURF CITY NORTH CAROLINA A TROPICAL STORM WARNING IS IN EFFECT FOR... * FLAGLER/VOLUSIA COUNTY LINE FLORIDA TO SOUTH SANTEE RIVER SOUTH CAROLINA * NORTH OF SURF CITY NORTH CAROLINA TO WEST OF WATCH HILL RHODE ISLAND * CHESAPEAKE BAY SOUTH OF NORTH BEACH * TIDAL POTOMAC RIVER SOUTH OF COBB ISLAND * DELAWARE BAY * LONG ISLAND AND LONG ISLAND SOUND * PAMLICO AND ALBEMARLE SOUNDS A TROPICAL STORM WATCH IS IN EFFECT FOR... * WATCH HILL RHODE ISLAND TO STONINGTON...MAINE * MARTHA'S VINEYARD...NANTUCKET...AND BLOCK ISLAND INTERESTS ELSEWHERE ALONG THE NORTHEAST COAST OF THE UNITED STATES SHOULD MONITOR THE PROGRESS OF ISAIAS. ADDITIONAL WATCHES OR WARNINGS MAY BE REQUIRED LATER TODAY. A STORM SURGE WARNING MEANS THERE IS A DANGER OF LIFE-THREATENING INUNDATION...FROM RISING WATER MOVING INLAND FROM THE COASTLINE...DURING THE NEXT 36 HOURS IN THE INDICATED LOCATIONS. FOR A DEPICTION OF AREAS AT RISK...PLEASE SEE THE NATIONAL WEATHER SERVICE STORM SURGE WATCH/WARNING GRAPHIC AT HURRICANES.GOV. THIS IS A LIFE-THREATENING SITUATION. PERSONS LOCATED WITHIN THESE AREAS SHOULD TAKE ALL NECESSARY ACTIONS TO PROTECT LIFE AND PROPERTY FROM RISING WATER AND THE POTENTIAL FOR OTHER DANGEROUS CONDITIONS. PROMPTLY FOLLOW EVACUATION AND OTHER INSTRUCTIONS FROM LOCAL OFFICIALS. A STORM SURGE WATCH MEANS THERE IS A POSSIBILITY OF LIFE- THREATENING INUNDATION...FROM RISING WATER MOVING INLAND FROM THE COASTLINE...IN THE INDICATED LOCATIONS DURING THE NEXT 48 HOURS. A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA...IN THIS CASE WITHIN 24 HOURS. PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO COMPLETION. A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA...GENERALLY WITHIN 36 HOURS. A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS. TROPICAL STORM CENTER LOCATED NEAR 29.7N 79.9W AT 03/0900Z POSITION ACCURATE WITHIN 20 NM PRESENT MOVEMENT TOWARD THE NORTH OR 355 DEGREES AT 8 KT ESTIMATED MINIMUM CENTRAL PRESSURE 994 MB MAX SUSTAINED WINDS 60 KT WITH GUSTS TO 75 KT. 50 KT....... 50NE 30SE 0SW 20NW. 34 KT.......100NE 110SE 0SW 60NW. 12 FT SEAS..120NE 120SE 45SW 75NW. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 29.7N 79.9W AT 03/0900Z AT 03/0600Z CENTER WAS LOCATED NEAR 29.0N 79.9W FORECAST VALID 03/1800Z 31.3N 79.6W MAX WIND 65 KT...GUSTS 80 KT. 64 KT... 25NE 0SE 0SW 0NW. 50 KT... 50NE 40SE 0SW 20NW. 34 KT...100NE 120SE 0SW 60NW. FORECAST VALID 04/0600Z 34.8N 78.1W...INLAND MAX WIND 60 KT...GUSTS 75 KT. 50 KT... 50NE 40SE 0SW 20NW. 34 KT...110NE 140SE 0SW 60NW. FORECAST VALID 04/1800Z 39.4N 75.2W...INLAND MAX WIND 55 KT...GUSTS 65 KT. 50 KT... 50NE 60SE 0SW 0NW. 34 KT...110NE 130SE 0SW 40NW. FORECAST VALID 05/0600Z 44.4N 71.5W...INLAND MAX WIND 35 KT...GUSTS 45 KT. 34 KT... 0NE 120SE 0SW 0NW. FORECAST VALID 05/1800Z 48.6N 68.0W...POST-TROP/EXTRATROP MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 06/0600Z 52.0N 65.0W...POST-TROP/EXTRATROP MAX WIND 25 KT...GUSTS 35 KT. EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM ON DAY 4 AND 175 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY OUTLOOK VALID 07/0600Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 29.7N 79.9W INTERMEDIATE PUBLIC ADVISORY...WTNT34 KNHC/MIATCPAT4...AT 03/1200Z NEXT ADVISORY AT 03/1500Z $$ FORECASTER BROWN

Tags: number storm advisory tropical

 

Tropical Storm Isaias Forecast Discussion Number 24

2020-08-03 04:43:45| National Hurricane Center (Atlantic)

Issued at 1100 PM EDT Sun Aug 02 2020 000 WTNT44 KNHC 030243 TCDAT4 Tropical Storm Isaias Discussion Number 24 NWS National Hurricane Center Miami FL AL092020 1100 PM EDT Sun Aug 02 2020 Isais has not become better organized on satellite and radar imagery at this time. The cyclone continues to produce vigorous deep convection but this convection continues to be displaced to the northeast of the center, and convective banding features are ill-defined. Air Force Hurricane Hunter observations show that the central pressure has not fallen since earlier today, and flight-level and SFMR-observed surface wind measurements from the aircraft indicate that the intensity remains near 60 kt. Although Isais will be moving through an environment of fairly strong southwesterly shear during the next day or so, it will also be traversing the warm waters of the Gulf Stream with its high oceanic heat content. The latter factor could result in the system becoming a hurricane near landfall. The official forecast is close to the intensity consensus, which keeps Isaias just below hurricane strength. It should be emphasized that there is little difference between a strong tropical storm or a category 1 hurricane, in terms of impacts. After landfall, the interaction with land and strong shear should result in steady weakening. Based on the global models, the cyclone is likely to become an extratropical cyclone after it moves into Canada and dissipate over the north Atlantic shortly thereafter. The motion continues to be slightly west of due north or 345/8 kt. There has been no significant change to the track forecast reasoning. Over the next couple of days, Isaias is expected to accelerate north-northeastward on the east side of a large 500 mb trough over the eastern United States and then turn northeastward in 3 to 4 days as it moves through the mid-latitude westerlies. The official track forecast is very close to the previous one and similar to the latest corrected dynamical model consensus. This is between the GFS, which shows a slightly faster motion and the ECMWF, which is slightly slower. Key Messages: 1. There is the danger of life-threatening storm surge inundation of 2 to 4 feet above ground level from Edisto Beach South Carolina to Cape Fear North Carolina along the immediate coastline and adjacent waterways. Life-threatening storm surge is possible along the North Carolina coast from Cape Fear to Duck. Residents in these areas should follow advice given by local emergency officials. 2. Tropical storm conditions will spread northward within the Tropical Storm Warning area from Florida to Maryland through early Tuesday. Isaias is expected to be near hurricane strength when it reaches the coast of northern South Carolina and southern North Carolina Monday night, and strong tropical storm force winds are likely with hurricane conditions possible in the Hurricane Watch area. 3. Heavy rainfall from Isaias will continue to result in potentially life-threatening flash flooding in the Northwest Bahamas through tonight. Flash and urban flooding, some of which may be significant in the eastern Carolinas and the mid-Atlantic, is expected through midweek along and near the path of Isaias across the East Coast of the United States. Widespread minor to moderate river flooding is possible across portions of the Carolinas and the mid-Atlantic. 4. Tropical storm conditions are forecast to spread northward across the remainder of the U.S east coast on Tuesday and early Wednesday. A tropical storm watch is in effect through Long Island Sound and additional watches and warnings will likely be issued on Monday. FORECAST POSITIONS AND MAX WINDS INIT 03/0300Z 28.5N 79.8W 60 KT 70 MPH 12H 03/1200Z 29.7N 80.0W 60 KT 70 MPH 24H 04/0000Z 32.2N 79.3W 60 KT 70 MPH 36H 04/1200Z 35.9N 77.3W 55 KT 65 MPH...INLAND 48H 05/0000Z 40.5N 74.0W 40 KT 45 MPH...INLAND 60H 05/1200Z 45.5N 70.0W 35 KT 40 MPH...INLAND 72H 06/0000Z 50.0N 65.5W 30 KT 35 MPH...POST-TROP/EXTRATROP 96H 07/0000Z 55.5N 56.5W 25 KT 30 MPH...POST-TROP/EXTRATROP 120H 08/0000Z...DISSIPATED $$ Forecaster Pasch

Tags: number discussion storm tropical

 

Sites : [568] [569] [570] [571] [572] [573] [574] [575] [576] [577] [578] [579] [580] [581] [582] [583] [584] [585] [586] [587] next »