A dangerously hot Fourth of July

Yes, it's Fourth of July weekend, and it's the 250th celebration of our nation's founding. BUT, the oppressive heat and humidity have risen into dangerous levels. Prudence and caution should both be watchwords the next few days. This isn't a typical summertime heat wave...it's much worse.

The National Weather Service has issued an Extreme Heat Warning which covers Mecklenburg County from 10 o'clock this (Friday) morning all the way through 8:00 p.m. Saturday evening.

This morning's thermometer readings in the mid- to upper 70s will soar above 100º this afternoon. Combined with dew points in the 70s, that will make it feel close to 110º later today. Temperatures tonight won't drop much - if any - below 80º, so there won't be much relief even without the sun's rays continuing to scorch the area.

Saturday - July 4th - conditions look much the same, but with the likely addition of strong to severe storms by mid-afternoon. Damaging straight line winds - and lightning! - will be the chief threat, which may drop temperatures but not the oppressive humidity. All these factors could make outdoor celebrations dangerous for people and pets, along with affecting fireworks displays (those which aren't cancelled):

Sunday will also have the chance for strong to severe storms, with high temperatures close to 100º yet again. At the moment there isn't a heat warning covering the latter weekend day, but that may change as the National Weather Service reviews the data.

So be careful this weekend, practice heat safety, and keep an eye on each other for symptoms of heat illness.

Heat wave, heat dome, heat warnings...yeah, it's gonna be hotter than normal!

Today (Wednesday) marks the beginning of a multi-day stretch of much above average heat for this time of year. Normal July temperatures in Mecklenburg County range from morning lows near 70º to daily highs near 90º. Those figures may feel cool given the forecast through the upcoming weekend.

The much ballyhooed "heat dome" is the culprit. This weather feature can form when the summertime jet stream pushes well up into Canada, leaving high pressure to stagnate over the Eastern U.S. In high pressure systems the air sinks and heats up, versus rising and cooling as in a low pressure setup:

In addition, the oppressive humidity trapped at the surface under this heat dome makes it difficult for the body to cool down via sweating. The double whammy of above average heat plus humidity - often expressed as the "heat index" - can be dangerous to people and pets, especially when this situation lasts for several days.

This afternoon temperatures will top out in the upper 90s, and the heat index will be several degrees above that. By dawn Thursday local thermometers will only dip into the low to mid-70s, so there won't be much overnight relief. Tomorrow's highs then look to break the triple digit mark. This forecast will be similar through the upcoming holiday weekend.

Be very careful during outdoor activities to remain hydrated, take frequent breaks in the shade or air conditioning, and keep an eye out for others who may be affected by these extreme conditions. This isn't typical summer heat.

A comfortable start to the week, plus a wild weather anniversary

A backdoor front pushed through Mecklenburg County Sunday evening on its way south and west. The northeasterly breeze following that boundary will help today's - Monday's - afternoon highs top out only in the upper 80s under partly sunny skies. Dew points remain in the sticky range, with chances of a few scattered showers still possible today.

Those northeasterly breezes will usher in slightly cooler and less sticky air by this evening, such that local thermometers will begin Tuesday morning with readings in the mid-60s. Under mostly sunny skies tomorrow's highs will climb back to the 90º mark, just about average for late June. By Wednesday, however, temperatures look to boost well above summertime normal readings as a strong high pressure system builds a heat dome across the eastern half of the nation.

Such a heat dome was in place 14 years ago today, on June 29th 2012. That evening's weather phenomenon imprinted the term "derecho" onto the Virginian psyche. Here is a radar loop from that day:

And this graphic shows the wind damage along the path of that cluster of storms, which caused multi-day power outages during the hottest part of the summer of 2012:

At the moment there doesn't seem to be any threat from another derecho reaching the Old Dominion. However, the hot weather arriving later this week is not just typical summertime heat. It will be an extreme event, and folks would be wise to heed heat safety tips over the next several days. This is not weather hype. Heat kills more people on an annual basis than any other weather feature.

The week ahead: A steady climb toward above average heat

The 90s originally forecast for Saturday didn't happen, nor will today's (Sunday's) afternoon temperatures in the mid-80s be as hot as thought late last week. Both days were a few degrees below the late June averages. Although the temperature forecast didn't verify, the somewhat cooler conditions were welcome.

What did occur as forecast were storms, which deposited liquid totals from one-third to three-quarters of an inch across Mecklenburg County. That wasn't a lot, but at this point amid the worsening drought any rainfall is welcome. This morning local thermometers began the day recording an interesting series of 68º, 69º, 70º, and 71º respectively at Clarksville, Chase City, Boydton, and South Hill. That's a nice progression!

More showers and storms will roll across the county later today, with a few of those bringing strong winds along with lightning and downpours that could last until after sunset. After morning lows near 70º again, Monday looks to begin somewhat cloudy. However, skies will slowly clear later in the morning. Temperatures tomorrow will top out in the upper 80s.

Then the heat returns with a vengeance. Afternoon highs will climb through the 90s Tuesday and Wednesday into the triple digits later this week. NWS Wakefield is describing this oncoming heat wave as the fiercest since 2012. THAT was a hot summer! For emphasis check out this Hazards graphic: 

Prepare for a hot stretch ahead!

Summer heat, humidity, and storms...they go together

Hope folks enjoyed the brief cool break this week. A typical late June heat dome is setting up across the central and eastern U.S., and that feature will last a while per these two forecast graphics:

Today's (Friday's) afternoon temperatures will boost into the mid-90s as dew points climb back into the uncomfortable range. Those two factors will lead to chances of storms, a few of which are possible later today and tonight.

By dawn Saturday temperatures will hover near the 70º mark before beginning their march upward into the 90s. Tomorrow afternoon a slow-moving cold front will be draped west-to-east across Virginia. Meanwhile an upper level disturbance will cross the region. That combination has convinced the Storm Prediction Center to issue a Slight Risk - level 2 of 5 - for severe storms over the southeastern third of the state (including Mecklenburg County). 

The chief threat will be damaging straight line winds. Make sure to have at hand at least two methods of receiving weather warnings (an inexpensive NOAA weather radio ought to be one of them). If a severe thunderstorm warning is issued take shelter on the lowest floor of a sturdy building, away from windows. 

Saturday night looks to be wet, but by sunrise Sunday (5:57 a.m. at the Kerr Dam) the cloud cover will have thinned out. The latter weekend day will then feature mostly sunny skies with highs again in the 90s. More storms are possible Sunday afternoon, but the threat of severe weather will be less than Saturday's. Even so, remember "If Thunder Roars Head Indoors". Lightning is a bigger threat than many folks realize.

As for next week, temperatures could top the triple digits by Wednesday. Brace for it.

A taste of the 80s before the 90s roar back into town

Ahhhh....feel that? The cool dry air mass behind Tuesday's cold front resulted in a very comfortable Wednesday morning. Chase City won the prize for this morning's coolest temperature of 58º, but other local thermometers weren't much higher. The combination of a northerly breeze and the dry air will keep this afternoon's temperatures in the mid-80s for daily highs. 

Yesterday's cold front passage also triggered showers and storms which were more prolific rain-producers than originally thought. Area rain gauges recorded totals from 0.50" in Boydton to 1.04" in South Hill. And there was at least one storm report of a tree down along Buggs Island Road not far from the dam.

Enjoy this brief cool break, because summer's heat is knocking on the doorstep. Thursday morning low temperatures will be in the low 60s once again, but southerly winds and the high sun angle of late June will combine to boost tomorrow afternoon's highs into the 90s. Humidity levels will also be on the rise, so expect a return of the stickiness factor.

In fact, the next week to ten days looks very warm. These two graphics indicate hazardous heat levels creeping into Virginia early next week and then sticking around through the following weekend:

Another round of storms late Monday into Tuesday

Dew points around Mecklenburg this Monday morning have risen into the low 70s, about ten degrees higher than Sunday's rather comfortable values. The "stickiness quotient" is thus much higher today, especially given forecast afternoon highs in the mid-90s. That moisture, plus a lee trough, plus a cold front slowly edging eastward from the Ohio Valley, has convinced the Storm Prediction Center to issue a Slight Risk - level 2 of 5 - for severe storms today.

Those storms will arrive later this afternoon, likely near the dinner hour. The chief threats will be damaging straight line winds and the always dangerous lightning. Keep at least two weather warning sources at hand, and if a warning is issued take shelter on the lowest floor and away from windows. And remember, "If Thunder Roars, Head Indoors". It doesn't pay to gamble with lightning!

Showers and storms look to continue into the late evening hours as that cold front slowly works its way across Virginia. Then, as a low pressure center develops nearby along the boundary, another round of convection will push through during mid-day Tuesday. Tomorrow will feature mostly cloudy skies until late afternoon, with temperatures topping out in the upper 80s. 

Rain totals won't be impressive from this system, but the hard and dry ground will make it difficult for the water to soak in. That could lead to some localized flooding during torrential downpours. Forecast precipitation totals from this latest system are shown in this graphic from NWS Wakefield:

It's not enough to break the drought, but at this stage any amount helps!