Month: July 2014

Tropical Depression #2 Unlikely A Major Threat

Miguel Pierre Tropics

Update: Not surprisingly, tropical depression 2 has degenerated to a tropical wave.

A tropical disturbance in Central Atlantic had become organized enough to be classified as tropical depression 2 yesterday. However, it doesn’t appear likely to be a major threat to anyone, at this time. The 5am National Hurricane Center forecast today, keep this under tropical storm strength through 48 hours. Then weaken and dissipate by 72 hours, before reaching the Lesser Antilles. No tropical storm watches or warnings have been issued for this region, for this reason.

5amNHCforecastCurrent water vapor imagery shows a very dry and stable environment just to the north and west of system, associated with high pressure system over the Central Atlantic.  This is keeping deep convection minimal around the low-level center. So little change in strength is likely over the next couple days. Afterwards, the depression will run into more shear being produced by a TUTT (tropical upper tropospheric trough) over the Western Atlantic and Eastern Caribbean. Any land interaction with Puerto Rico or Hispaniola may also hinder further development down the road. For these reasons, our most reliable global models show very little development.  With these factors considered, the probability of this depression becoming a strong tropical storm or hurricane the next five days is very low.

wvimageThe depression will be carefully monitored through out this week. At this time, there is no reason for the anyone living along United States East or gulf coasts to be alarmed.  Any possible threat to United States is least a week away and will dependent on the pattern at that time. Current guidance shows a deep mid-latitude trough over the Eastern US for the 7-10 day period, that might force this system to recurve into open Atlantic. But there is a far greater chance the depression will not survive the hostile environment it will endure over next few days.

Humidity & T-Storms Return Briefly by Wednesday

Miguel Pierre Long-Range Discussions, Severe Wx

After a decent weekend and beautiful day today, warmer and humid airmass will start to return to the Tri-State area tomorrow. As southwesterly flow develop throughout the day. High temperatures will reach the middle to upper 80s, away from the south-facing coasts with dewpoints in middle to upper 60s. An isolated shower or thunderstorm is possible with daytime heating and instability. Wednesday will be even more humid with high temperatures in the upper 80s to lower 90s. There is a better chance of showers and thunderstorms with a cold front moving through region late in afternoon or evening. NAM and GFS forecast sounding show with  1000-2000 J/kg MLCAPE 500-700mb lapse rates 6.5 C/km to 7.0 C/km. Which supports some thunderstorms to become strong or severe, with strong winds and large hail. However weak shear values suggest thunderstorms will pulse up and down.

GFS Model forecast sounding for NYC at 18z (2pm ET) Wednesday. MLCAPE 1434 J/kg, L57 6.8 C/km and weak directional shear support pulse severe thunderstorms.
 GFS Model forecast sounding for NYC at 18z (2pm ET) Wednesday. MLCAPE 1434 J/kg, L57 6.8 C/km and weak directional shear support pulse strong to severe thunderstorms. 

After this cold front, pass a slightly cooler and less humid airmass will once again be over region for the rest of the week. High temperatures will be in the lower to middle 80s with sunshine. More humidity and thunderstorms may return again, on Sunday as another frontal system approaching the region. However, the big story this summer seems to be lack of extreme or prolonged heat waves.  This has been due to the reloading of strong ridge over NE Pacific or West Coast causing more troughs to dig into East. Long-range guidance continues to show this pattern continuing for the next couple of weeks, at least.

Severe Thunderstorms Hit Long Island 7/15/14

Miguel Pierre Severe Wx ,

This past week, we had a storm event, wasn’t a big severe weather or tornado outbreak that was being suggested by other sources for Northeast and Mid-Atlantic regions. But there were some severe thunderstorms for a parts of the area. These are base velocity radar images from thunderstorms that hit Long Beach and and Jones Beach in Long Island, New York. These storms produced wind gusts up to 60mph near Point Lookout, knocking down trees over parts Nassau and Suffolk Counties. Heavy rainfall from these t-storms also caused localized flash flooding.

Image courtesy of Weather Underground.
Base Velocity loop showing strong winds, courtesy of Weather Underground.

It’s not a relative common occurrence, for severe thunderstorms on Long Island. As the marine layer from a wind direction off the ocean waters, tends to cause thunderstorms to collapse as they approach the coast. However, on Tuesday a cap was present and winds were out southwest direction (over more land). Which allowed more instability to develop, with some sunshine. The  sounding below, is from a balloon launch Tuesday evening, from the National Weather Service office in Upton, NY showed 2009 J/kg of MLCAPE (mixed-layer cape). That is high amount of buoyancy in the lowest 100mb layer for this area. This instability also was juxtaposed with 31kts of 0-6km shear and 29kts of 0-1km shear. Which contributed to more organized and stronger updrafts and downdrafts in thunderstorms.

OKX Sounding from balloon launch at 8pm Tuesday 7/15/14
OKX Sounding from balloon launch at 8pm Tuesday 7/15/14