Aug 24, 2012: Some Storms Monday/Tuesday

Forecast Highlights:

– Slight cool down this weekend; more clouds, a little rain possible
– Scattered storms for Monday/Tuesday
– Warmth potential by late next week


Friday, August 24 Observations:

Partly cloudy skies were observed across the area as warm 850mb temperatures resulted in a slightly warmer day for most places. High temperatures reached the mid 80s inland, upper 80s in most of the immediate NYC area, and the low to mid 80s in Long Island and southern CT. The highest temperature was 91 degrees in Teterboro, NJ; the lowest high was 81 degrees in New London, CT.

Forecast Overview:

The weather pattern across the Northeast and the Mid Atlantic region remains generally inactive with the exception of scattered storms on Monday and Tuesday associated with a cold front. More clouds with isolated showers will drift north into parts of the region over the weekend for the south, resulting in cooler temperatures, with highs in the upper 70s to lower 80s across most of the area. A cold front will move through the region on Monday into early Tuesday with more widespread clouds and scattered thunderstorms, mostly staying west of the area on Monday while moving through overnight and into at least the first half of Tuesday. Temperatures for Monday are expected to be similar to those of Sunday, if not slightly warmer.

Tuesday’s temperatures are expected to be around the upper 70s to mid 80s range with scattered storms expected, more likely during the first half of the day but possibly for the second half should it be a bit slower than currently expected. Temperatures will slightly cool down on Wednesday and Thursday with a trough moving through the region; highs are expected to reach the upper 70s to lower 80s on Wednesday and upper 70s to mid 80s on Thursday, with lows on Wednesday night dropping into the 50s away from NYC, perhaps the upper 40s inland, with 850mb temperatures cooling down to about 10C and a high pressure over the region with mostly clear skies.

By late next week, ridging is expected to rebuild into the region. There is some uncertainty regarding what happens with Isaac’s remnants once they make landfall in the US, resulting in a variety of solutions for this time period, although at least a brief surge of heat is looking more likely at this time; should this surge of heat verify, it will not be long lasting, but it may signal 90+ degree heat making a return into parts of the region for the end of the meteorological summer.

Tropical Storm Isaac: Florida Targeted Twice

Since last night, Tropical Storm Isaac has finally managed to organize itself with convection sustaining itself closer to the center, allowing for Isaac to quickly intensify into a 65 mph tropical storm, stronger than expected last night. Isaac has also notably slowed down, and may very well become a weak hurricane prior to landfall in Haiti tonight. Isaac is still expected to weaken afterwards due to land interaction with Haiti and Cuba, likely taking it down to at least a moderate tropical storm. A general NNW path will continue for the short term, turning more to the NW as it passes through the northern parts of Cuba and through the Florida Strait.

Once reaching the Gulf of Mexico, Isaac appears to target Florida twice; first with a possible landfall near the Florida Keys, then with a second landfall near northwestern Florida. Isaac will turn more to the NW, but will not recurve straight up the East Coast, especially with some ridging to its north, a lack of a stronger trough to quickly pull it north, and steering currents still supporting a general NW track. The possibility is there that Isaac’s remnants may slide off the SE US coast and continue offshore from there, but the storm will not take a classic East Coast tropical cyclone track with a trough over the Northeast region later on Tuesday and Wednesday. Regarding Isaac’s intensity in the Gulf of Mexico, most models at this time show Isaac as a weak category 1 hurricane; although the extent of Isaac’s intensification will depend on how it survives its track through Hispaniola and Cuba, the possibility is there for more rapid intensification into a hurricane, perhaps up to category 2 intensity, in the eastern Gulf of Mexico.

Based on latest trends with Isaac in the short term it is increasingly likely its passage over Cuba will be shortened, which may also favor more intensification in the Gulf of Mexico region. At this time, I am expecting landfall somewhere within or near the general region between south of Tallahassee and Pensacola, Florida. Afterwards, there is more uncertainty with its remnants depending on the exact timing and location of the landfall along with the timing of the Northeast cold front; there isn’t high confidence yet regarding the remnants, although two main possibilities are for the remnants to drift north into the south/central US or to slowly drift ENE through the SE US and then offshore.

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