Severe weather in the Northeast U.S.; updates on 90L, 91L, Leslie and Michael
A significant severe weather outbreak is underway today across much of the Northeastern U.S., including metro New York City and Philadelphia. NOAA's Storm Prediction Center has placed the region in their "Moderate Risk" area for severe weather. A fall-like low pressure system with a very powerful cold front will sweep through the region today, triggering widespread severe thunderstorms that may organize into a "derecho" event with damaging winds covering a large swath of the Northeast. A few tornadoes may accompany the event, and several tornado warnings have already been issued in New York, with a possible tornado touchdown in the Point Breeze section of the Rockaway peninsula in Queens. The same storm system killed four people on Friday in northeast Oklahoma; three of the deaths occurred when strong thunderstorms winds blew a mobile home into a ravine. Record heat was observed in advance of the storm's cold front yesterday; Wichita Falls, TX hit a record high of 109, the hottest temperature ever recorded there so late in the season. When the cold front blew through at 7 pm CDT, the temperature dropped 15 degrees in 16 minutes, falling to 66 degrees by midnight. Wunderground meteorologist Shaun Tanner has more on the severe weather potential for the Northeast in his blog.
Figure 1. Severe weather potential for Saturday, September 8, 2012.
90L in the Gulf not a threat to develop
A partial remnant of Hurricane Isaac off the coast of the Florida Panhandle, Invest 90L, continues to be disrupted by wind shear, and no longer has time to develop before landfall occurs along the Florida Gulf Coast tonight or Sunday. Visible satellite loops show that 90L has a small area of poorly organized heavy thunderstorms, which will bring some areas of heavy rain to Florida today and Sunday.
Leslie still struggling with cool waters
Tropical Storm Leslie continues to feel the impact of the the cool waters it stirred up due to its long pause south of Bermuda, and remains a 65 mph tropical storm. The storm has no eyewall, as seen on satellite loops, but has cleared out a large cloud-free center. As Leslie continues to move north over warmer water, the storm should be able to build an eyewall and become at least a Category 1 hurricane. However, Leslie is expected to pass far enough to the east of Bermuda today and tonight that top winds of 45 mph will be observed on the island. Bermuda radar shows a large area of heavy rain from Leslie is very close to the island.
Figure 2. Morning radar image of Tropical Storm Leslie from the Bermuda radar.
Forecast for Leslie
The strong trough of low pressure pulling Leslie to the north will bring Leslie very close to Newfoundland, Canada by Tuesday night or Wednesday morning. At that time, Leslie should be weakening due to cooler waters and increased wind shear, and is likely to be a tropical storm. Heavy rain will be the main threat to Newfoundland. The latest 11 am EDT NHC wind probability forecast calls for a 24% chance that Leslie will be a Category 1 or stronger hurricane Wednesday morning at 8 am EDT, when the storm will be near Newfoundland. Even if the core of Leslie misses Newfoundland, the island will still likely experience tropical storm-force winds, since 39+ mph winds will probably extend outward from its center 180 miles to its west on Tuesday and Wednesday. Large swells from Leslie continue to pounding the entire Eastern Seaboard, and are creating beach erosion and dangerous rip currents.
Figure 3. Hurricane Michael as seen by NASA's Aqua satellite at 11:50 am EDT Friday September 7, 2012. At the time, Michael was a Category 2 hurricane with 105 mph winds. Image credit: NASA.
Hurricane Michael weakens to Category 2
Hurricane Michael remains a Category 2 storm with 105 mph winds, out over the open mid-Atlantic Ocean. Satellite loops show that Michael is still an impressive storm with a well-developed eye. None of the models show that Michael will threaten any land areas during the coming five days, and Michael will likely die at sea over cold waters northeast of Newfoundland in 5 - 7 days.
91L off the coast of Africa
A tropical wave that emerged off the coast of Africa on Friday has been designated Invest 91L by NHC today. Most of the reliable computer models are predicting that 91L will develop into a tropical depression by Wednesday. None of the reliable computer models foresee that this storm will be a threat to the Lesser Antilles Islands, but it is still early to be assuming that 91L will recurve harmlessly out to sea.
Jeff Masters
Reader Comments
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http://www.met.sjsu.edu/weather/models/wrf_wf.htm l
For some reason I am unable to post pics or links.
That is obviously a very big hurricane wind field.
Come on, I don't think this September will feature the opposite extreme as what this past March brought to much of the Great Lakes, plains, and on eastward when we were transitioning into spring and we got June-like weather. December-like weather in September, that just is impossible and i don't buy it.
From there, click model graphics and then click WRF 12 and 3 km TC genesis, west Africa.
This is the 850 mb temp, height, wind WRF 00z, 12k forecast for 0700 cdt today.
Pretty neat. Didn't even know San Jose State had a Dept of Meteorology. Thanks!
9Sept.3:05pmGMT: TS.Leslie had passed 133miles(214kilometres)East of Bermuda
The previous mapping of TS.Leslie
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Doesn't look like Leslie will come within Fujiwhara-distance (~900miles or ~1450kilometres) of Michael: Leslie's been moving too fast, and Michael's been moving too slow.
But they aren't so far apart that future interaction is impossible, yet. And because a Fujiwhara would affect both storms' paths...
Derived from the NHC's 9Sept12pmGMT ATCF data for TropicalStormLeslie and for HurricaneMichael
BHB-BarHarbor :: CWRW-FourchuHead :: YYT-St.John's :: YMH-Mary'sHarbour
All times in GMT
8Sept.06pm: TS.Leslie had been 1238miles(1992kilometres)West of H.Michael
9Sept.12am: TS.Leslie had been1222miles(1966kilometres)West of H.Michael
9Sept.06am: TS.Leslie had been 1197miles(1926kilometres)West of H.Michael
9Sept.12pm: TS.Leslie had been 1151miles(1853kilometres)West of H.Michael
9Sept.06pm: TS.Leslie was 1090miles(1754kilometres)West of H.Michael
A closure rate of 148miles(238kilometres) per day isn't sufficient to close the gap before the distance between the two starts increasing again. But if Leslie slows down while Michael speeds up...
Copy&paste bda, bhb, cwrw, yyt, 51.535n55.445w, ymh, 32.8n42.1w-29.0n62.5w, 33.3n42.3w-29.7n62.6w, 33.6n42.5w-30.5n62.6w, 33.7n42.9w-31.5n62.5w, 33.7n43.5w-32.7n62.3w into the GreatCircleMapper
The previous mapping of H.Michael
Viewing: 851 - 861
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