July 20 Weather Heat Advisory And Warning As This Wave Peaks

July 20 2020

Today should be the worst of this stretch. Temps will be comparable or a little hotter than yesterday when BWI reached 100ºF. The humidity will make it feel worse. Many areas will feel above 100ºF, but some may rise above 110ºF on the heat index.  This will be dangerous to be outside, and some experts began to mention wearing masks can add to early heat exhaustion.

Basically, if you can stay inside with air conditioning, this is the day to do that. Keep plenty of water to drink for you, kids, and pets.  Please do not walk dogs on pavement mid day through 7 PM.

Heat Advisory and Excessive Heat Warning

 

The Dew Point Tells A Lot

This is the true measure of moisture in the air. The Relative Humidity (RH) is a calculation of this and the actually temperature, so when it gets hotter, the RH goes down.

The Dew Point is where the moisture in the air will condense. The higher it is, the harder it is for your body to have sweat evaporate to cool you off.

The upper 70s on Delmarva is why there is an Excessive Heat Warning in place.

 

Beach Fog

When the Dew Point is higher than the water temperature, fog forms. If you were at the beach on Sunday, you may not have seen the sun until AFTER noon because of this.

 

Morning Satellite Loop

This morning a slight wind from the west high limit how widespread the fog holds.

 

 

Afternoon Forecast

How Hot?

The NAM has us in the upper 90s, but this has been cooler than verified lately… The HRRR is hotter.

 

The HRRR Model has many in central Maryland over 100ºF

 

Heat Index Forecast

 

Storm Relief

There may be a cluster of storms forming after 4 PM

As in recent months, there may be more storms than shown on the modeling.  With the high heat, any storms that form can contain dangerous lighting and high winds.

Radar Simulation —> Slider

 

Storm Outlook

Increased storm coverage each day this week, with a break by the weekend.

 

Records?

That will be tough to challenge with some of the hottest already set on those days

July 20    102ºF in 1930    
July 21    104ºF in 1930   
July 22    106ºF in 2011   
July 23    102ºF in 2011+