Heat Wave Delayed

While some intense heat is going to be building thru the Plains and Midwest this weekend and early next week, looks like a wrench has been thrown in the pattern to put a lid on the hot weather for our area. There has been a little bit of troughiness North of the area into Canada for the last few days. Forecast models have come into unusual agreement with the scenario that a trough digs and becomes stronger for Saturday. This means, that cooler temperatures will result at the surface along with more in the way of cloud cover. This will certainly make things feel nicer outdoors compared to the oppressive 90s, however what is still uncertain at this point is how any type of precipitation-making disturbance plays out. At least a few t-showers will probably threaten. Then during early next week, we will see if the heat is able to make it into the East Coast.

Saturday Afternoon 500mb Heighs and Vorticity

The Dog Days

It feels like a seasonal July out there with temps well into the 80s and dewpoints at modest levels, though it does not “feel” oppressively humid. Approaching front is going to bring the threat of some isolated showers or storms late Wed into Thurs, and then watch out! Indications are that the heat is going to build to some oppressive levels for the weekend and week ahead. More details over the next couple of days.

Intense Sunday of Storms

Yesterday was a very busy and intense day of severe thunderstorms across the Mid-Atlantic. Particularily the SE PA – NJ – NYC corridor. What helped fuel the storms to blow up so rapidly was likely an area of clearing skies that developed during the morning hours. This allowed for temps to jump and everything destabilized quickly, leading to rapid development of severe t-storms. It was also very scary in that these storms had a tremendous amount of cloud-ground lightning strikes and they took place in the wrong places, like the highly populated beaches. In some instances, storms were mature enough that anvils out of the top of thunderstorms produced lightning strikes, some 15-20 miles away from the actual rain/t-storm. This type of phenomena is dangerous as it can catch many people off guard.

 

 From the National Weather Service – JetStream Online school for Weather

Rainfall Recap

All the ingredients came together for a widespread rainfall event across the mid-Atlantic and northeast yesterday and last night. Even though there were some flooding problems, the intense overnight rainfall never really panned out. That kept most rainfall totals in the 1-2 inch realm, which prevented major and widespread problems. The areas that had the heaviest rains as indicated by the Doppler Radar estimates below saw intense thunderstorms in the late afternoon and early evening hours on Wednesday dropping at least 1 inch of rain in a short amount of time.  Those thunderstorms produced damaging winds and hail which mainly caused tree damage from SE PA through Central NJ.

 

Radar Estimated Rainfall 10 AM 7/23 – 12:45 PM 7/24 

 

Looking ahead, we only get 1 day of quiet weather before the chance for showers and thunderstorms returns to the forecast for the weekend. However, these look like “garden variety” showers and thunderstorms, with the greater threat coming on Sunday.

 

Extended Threat for Heavy Rain

After neearly a week in a hot & humid airmass, we’ll have to watch for the potential for some heavy rain across the area the next few days. A slow moving frontal system & upper-level energy will create a prolonged period with a threat of rain beginning tonight, lasting through early Thursday Morning. To be clear, the rain shouldn’t be continuous, but will be more of the occasional variety, and any one storm could produce torrential rain, when an inch or two of rain may fall in an hour or two. It should be noted that this rain is much needed in some spots especially in Central & Southern NJ where the thunderstorms so far this year have by and large missed the area leaving numerous brown lawns behind.

NAM Model 48 Hour Accum Precip Tues-Thu Afternoon

Tropical Update

There are currently 2 tropical storms in the Atlantic Basin, Cristobal off the US East Coast and Dolly just emerging into the Gulf of Mexico.  Since Cristobal is closer to our area, we’ll talk about it more today. The only real impacts to that this storm will bring will be some increased surf along the coast. The storm is currently pulling away from the North Carolina coast and should continue to push to the north and east towards the Canadian Maratimes. As of the 11 AM National Hurricane Center Update, the storm has winds of 65 MPH. given that the storm is moving right over the warm Gulf Stream waters, it is not impossible that there could be some minor strenghtening, though the system probably will not reach hurricane status.

Tropical Storms Cristobal & Dolly 7/21/08 12:41 PM

How hot can it get in a vehicle?

With the heat wave now in full force across the Mid-Atlantic and Northeast, let’s take a look at how dangerous it really can be inside of a vehicle. The National Weather Service office in Milwaukee, WI did a quick study to find out just how hot the inside of a car can get when turned off and parked in the hot sun. The outside temperature during the experiment was between 92 and 95 degrees and the dark blue vehicle was positioned so the sun was at its rear. At 1245 PM, the interior temperature with the Engine and AC on was 83 degrees. The car was then turned off and within 15 minutes, it reached 120 degrees! The peak temperature of 134 degrees was reached by 3:15 PM. This definitely goes to show nobody (including pets) should be left in a parked car. For more details on the study, go to http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=mkx&storyid=14039&source=0.

We’re having a heat wave….

Well it was only a matter of time until that July heat wave and it looks like it is here. The good news with this particular heat wave is that it is slow and gradual as most spots just approach 90 thru today, plus dewpoints remain low, so it does not become humid really until Friday. High pressure at all levels is in firm control and will strengthen the next few days. This is going to be a long period of heat, but again should not be terribly excessive or oppressive (still always take the usual recommended precautions). Friday looks to be the hottest day of the week with temperatures in the big cities likely climbing into the mid 90s.

 

What exactly are Rip Currents

Over the weekend, rip currents were found along the Atlantic Coast, especially at the Jersey shore where unfortuntaely two people were killed and one is missing. The rip currents were mainly a result of former Hurricane Bertha, hundreds of miles out in the Atlantic. So what exactly is a rip current and how do they form? A rip current is a narrow channel of water near the shore that flows out to sea and can extend a couple hundred feet. You typically find rip currents threatening when tropical systems or strong storms are out over sea, which sends water and wind propogating shoreward. As a wave breaks a sandbar this sets up the strong current (thru the whole depth of the water, including the surface). The best way to spot a rip current, is to look for unusually calm water and the channel or rip current typically appears to be a different color.

from www.loving-long-island.com

Upcoming Summer Dog Days

Today may be the last widespread, stratiform rain that the Northeast and parts of the Mid-Atlantic see in awhile. The front that went thru last night and early today held together rain showers unusually well for this time of year. But, thru the work-week ridging starts to build and it is going to turn increasingly warmer and more humid. That stretch where we saw a thunderstorm threat nearly every day has diminished and it is going to be a dry period of weather right into the weekend. The only thing that might disturb it would be Mesoscale Convective Systems (a complex of thunderstorms) that would ride along the top of the ridge, but that should stay well to our North and West.

Monday Morning Radar

Hurricane Bertha Update

 

Bertha continues to hold her own out in the Central Atlantic Ocean. Bertha has been around for approximately 1 week already and has shown herself to be rather formidable having been a category 3 hurricane for a time. A few days ago I mentioned that Bertha will likely remain east of Bermuda, and that still seems to be the case. But with rather weak steering flows, it is coming a bit too close to comfort, and there is now a Tropical Storm Watch for Bermuda. The good news is that further significant intensification is not expected before the storm finally starts accelerating northeastward. Have a great weekend!

Relief!

 

After quite a few sticky days across the area, a cold front crossed the area last night which has brought cooler, but more importantly less humid air into the region. Yesterday at this time dewpoints (an absoulte measure of moisture in the air) were near (or even a little above) 70. Today however, those readings are generally in the low and mid 50’s, with a few 40’s dotting the map in northern parts of NJ. This spectacular weather will continue on Friday, before humidity starts to return for Saturday. But the good news is that Saturday should remain dry, as should much of Sunday before a cold front approaches the region on Sunday Night. Enjoy!

Storms Tonight, Less Humid Tomorrow

Thus far the showers and storms have stayed mostly away from the area, with the heaviest showers and storms remaining north of the area. At this point it appears that a few broken lines of showers and storms may cross the area tonight, with skies starting to clear out towards morning. Behind the front, temperatures won’t cool off that much…but humidity levels will be low…particularly by mid-July standards.  Furthermore, dry weather should prevail until at least Sunday afternoon, though the humidity starts to creep back in on Saturday.

Hurricane Bertha

As we would expect this time of year, and as we mentioned in the blog last week, activity is starting to pick up in the tropics.  Early yesterday morning Bertha became the first hurricane in that Atlantic Ocean this season. In a favorable area for development, Bertha rapidly intensified from a storm with 75 MPH winds (marginal Category 1 Hurricane) to a Category 3 storm with 115 MPH winds (Major Hurricane) in about 12 hours. However, it looks like today Bertha is moving into a more hostile environment above the surface and over an area of cooler ocean temperatures which is starting to weaken the storm. Either way this system should probably stay east of Bermuda and have minimal if any impacts on land. We’ll continue to keep an eye on Bertha and the rest of the Tropical Atlantic.

Hurricane Bertha 6:45 AM 7/7/08

Looking Ahead at the New Week

Hope you all had a good Independence Day weekend! Mother Nature has left the area in a very steamy air mass to start off the new week. So far temperatures haven’t been too hot, but humidity levels are quite high, dewpoints are right around 70. (Generally anything above 60 begins to feel uncomfortable) Humidity levels likely won’t drop much until after the passage of a front Wednesday Night.  Until thien in this soupy air mass, showers & storms could pop up at nearly any time. And through Tuesday, any storms that do form may not move quickly at all, raising the potential flood threat. The second half of the week is looking much more comfortable and drier. There is the potential for a wave to develop well south of the area towards the end of the week, and perhaps spread some moisture as far north as the Philly area, but we’ll see how that turns out.