Heat Advisories Extended to Friday

It sure is hot and humid today.  Cloud cover has kept temperatures a little bit lower in Southern New England when compared to Central New England.  The humidity is really the story.  Anyone who went outside today knows how heavy the air is to breathe.  This is no problem for our friends in the South but we just aren't used to it.  The unstable air mass has allowed showers and thunderstorms to pop south of the Mass Pike, mainly in CT.  I definitely overlooked the heavy rain potential for today when evaluating which in hindsight is really dumb.  With the moisture in the air showers/thunderstorms were bound to pop.
NOAA GOES_East Visible Satellite/Radar composite 315 PM
These storms are cranking in CT where a Severe Thunderstorm Warning in ineffect for portions of Windham and Tolland counties.  The dew points are much higher in Southern New England than in Northern New England.
3 PM Dew Points (Image NCEP/NOAA)
As a result here is a summary of temperatures, dew points and heat index for various Southern New England locations as of 4 PM,
4 PM temperatures via NWS Boston
What stands out to be is the significant difference the dew points in the 70's make.  Lawrence and Concord are both at 97 but the heat index is only 1-3 degrees higher.  Meanwhile Hartford is a staggering 95/76/108 split which is just nasty.   Like yesterday the convection will wane after sunset but the dew points will not.  The dew points will invade Northern New England as well.  Here are the 2 AM dew points
19z HRRR 2 nm dew points 2 AM (image Weatherbell)
But on the bright side if you want to get up to watch the Perseids Meteor Shower cloud cover should be minimal in interior MA/RI.  In other areas, especially where it is raining today fog is likely.
19z HRRR % Cloud Cover 2 AM Friday (Image Weatherbell)
The only thing that will keep temperatures down tomorrow is more cloud cover and rain but as you can see in the chart above the high dew points make it feel just as bad.  As a result a heat advisory has been posted again.
NWS Boston Headlines
The boundary remains stalled in Northern New England with the closest kicker still in the Midwest.  So tomorrow is a repeat of today with a better chance of rain..  Here is the projected surface chart tomorrow AM
WPC Surface Forecast 8 AM 
Here are the forecast high temperatures
NWS NDFD Max temps Friday (image Weatherbell)
Winds will be rather gusty tomorrow as they are today along the South Shore/Cape (thanks Jane for the report!) So just like today be careful if you heading to the beach to beat the heat as rip currents will be moderately strong.  If you want to head north the water is slightly cooler but they also have a low risk of rip currents.
Southern New England Surf Zone forecast (image NWS Boston)
Saturday and Sunday look similar to today in SNE.  I would pick Saturday over Sunday at the moment.  Low pressure will moved through Central New England Sunday so most of the rain should fall to our north but we will remain in the sticky air mass.

Stay cool/dry.

-Zack Green


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