12:20 PM | The month of July was cooler-than-normal on a nationwide basis; August also looks cool for most

Discussion

The month of July ended on a cool note throughout a good part of the country with 1456 cold temperature records set nationwide in the past week compared to only 130 warm temperature records. In fact, in dramatic contrast with last summer, the nation as a whole ended up cooler-than-normal for July by 0.47 degrees Celsius (source NCEP CFSv2) despite the excessive heat in the Northeast US during an 8-day stretch from the 14th to the 21st. The two main areas across the country that ended July with warmer-than-normal temperatures included the Northeast and the western US. In the Mid-Atlantic region, warmer-than-normal temperatures for July increased as one headed up I-95 with DC at +1.4 degrees, Philly +2.5 degrees, and New York City +3.3 degrees.

As far as August is concerned, it appears that the recent pattern of cooler-than-normal weather across the Central Plains, Midwest, Mid-Atlantic and Northeast will continue. The latest NCEP CFSv2 forecast map of temperature anomalies for August has the vast majority of the nation cooler-than-normal with the only exceptions being parts of the Pacific Northwest and the Gulf coastal region in the south-central part of the country.

7:00 AM | Occasional showers and possible thunderstorms today from the latest in a series of strong cool fronts

6-Day Forecast

Today

Mostly cloudy, humid, cool, an occasional shower and maybe a thunderstorm or two, some of the rain can be heavy, highs near 80 degrees

Tonight

Mostly cloudy, mild, evening showers still likely, maybe a thunderstorm, lows in the mid 60’s

Friday

Mostly sunny, comfortably warm, less humid, mid 80’s

Friday Night

Partly cloudy, pleasant, mid 60’s

Saturday

Partly sunny, warm, showers and thunderstorms likely, mid 80’s

Sunday

Mainly sunny, pleasant, low 80’s

Monday

Mainly sunny, pleasant, near 80

Tuesday

Partly sunny, still comfortable, maybe a few showers, low 80’s

Discussion

Another rain event has begun for the Mid-Atlantic region as a cool front approaches from the Great Lakes. Showers and scattered thunderstorms up and down the east coast today will dump more rainfall in areas where grounds are already quite saturated. Improvement will occur on Friday behind the front, but then another cool front could generate some showers and thunderstorms in the Mid-Atlantic region from Saturday into Saturday night. Very pleasant weather will follow that secondary frontal system on Sunday and Monday with plenty of sunshine and comfortable temperatures and humidity levels for early August.

Video

httpv://youtu.be/iV5xAZSn55I

7:00 AM | Shower threat increases today and then continues on Thursday with cool frontal passage

6-Day Forecast

Today

Mostly cloudy, cool, showers likely this afternoon, maybe a thunderstorm, highs in the low 80’s

Tonight

Mostly cloudy, mild, chance for showers and thunderstorms, lows in the upper 60’s

Thursday

Mostly cloudy, humid, showers likely and maybe a thunderstorm or two, some of the rain can be heavy, low 80’s

Thursday Night

Mostly cloudy, mild, still the chance for showers and thunderstorms, upper 60’s

Friday

Mostly sunny, warm, mid 80’s

Saturday

Partly sunny, warm, chance for a couple of showers and thunderstorms late in the day, low-to-mid 80’s

Sunday

Mostly sunny, comfortable, low 80’s

Monday

Mostly sunny, still comfortable, low 80’s

Discussion

While the month of July will end up with above-normal temperatures around here, it will close out on a cooler-than-normal note across the Mid-Atlantic region. In fact, the last week has featured cooler-than-normal weather across much of the nation with 1,122 cold temperatures records being set as compared with 173 high temperature records. High pressure will give up control of our weather today as it slides offshore and moisture will increase rapidly from our southwest. Clouds will thicken up this morning and showers are possible during thr afternoon hours. A cool front will approach the region on Thursday and this will enhance our chances for showers and thunderstorms and some of the rain can be heavy. The front should push off the east coast by Friday and this will pave the way for a nice close to the week with sunshine returning on Friday. The weekend should turn out to be mostly dry, but another frontal system will bring the chance for a couple of showers and thunderstorms to the area later Saturday.

Video

httpv://youtu.be/su__igLBJFY

1:30 PM | Comet PANSTAARS was a disappointment, the cicada invasion was a dud, and now Comet ISON may turn out to be a bust

Discussion

Meteorologists are not the only ones to have occasional trouble making accurate predictions – astronomers and entomologists can certainly be added to the list. First, there was Comet PANSTAARS which was supposed to be an impressive sight in the April skies, but it generally turned out to be a disappointment. Then there was the predicted massive 17-year cicada invasion which turned out to be sporadic at best in the Mid-Atlantic region. Now, it is looking more and more like the so-called “Comet of the Century”, Comet ISON, indeed may turn out to be a bust.

Astronomers have found that Comet ISON, which is currently moving towards the sun at 16 miles per second, has not brightened since mid-January. This might be the case if the comet is already out of ice particles in its body which melt as the comet moves closer to the sun creating a long, bright tail. Another theory is that the comet is covered in a layer of dust that snuffs out water vapor and other gasses that brighten the comet. Recent quotes from astronomers don’t hold out much hope and include such words as “Comet ISON has been on a standstill for more than 132 days” and “the future of comet ISON does not look bright”. Comet ISON was supposed to put on a spectacular show late this year as it is due to pass about 724,000 miles from the sun on November 28th. This relatively close pass was expected to create a massive tail that some scientists had predicted would even be visible in daylight.

The forecast should start firming up a bit in the near future. Comet ISON — whose nucleus is thought to be just 3 to 4 miles (4.8 to 6.5 km) wide — is slated to cross the "frost line" within the next few weeks, scientists say. This boundary, which lies about 230 to 280 million miles (370 to 450 million km) from the sun, marks the point at which ISON's water ice will start boiling off into space. (Until now, most of its activity has been driven by sublimating carbon dioxide.) ISON should brighten as it crosses the frost line, and scientists and skywatchers should get a better idea of how tough the comet is, researchers say. Some inbound comets haven't survived their trip past the frost line.

Throw in the Phillies season with the comets and the bugs and there certainly have been some disappointments this year.

7:00 AM | Next shot at showers/thunderstorms comes late Wednesday/Thursday with cool frontal system

6-Day Forecast

Today

Mostly sunny, comfortable, highs in the low-to-mid 80’s

Tonight

Partly cloudy, mild, lows in the mid 60’s

Wednesday

Partly sunny, warm, chance for a shower late, mid 80’s

Wednesday Night

Mostly cloudy, mild, chance for showers and thunderstorms, upper 60’s

Thursday

Mostly cloudy, humid, showers likely and maybe a thunderstorm, low-to-mid 80’s

Friday

Mainly sunny, warm, mid 80’s

Saturday

Mainly sunny, warm, maybe a late day or nighttime shower or thunderstorm, mid 80’s

Sunday

Partly sunny, warm, maybe a shower, low-to-mid 80’s

Discussion

High pressure will still control our weather today with copious amounts of sunshine and continued comfortable conditions and high temperatures in the low-to-mid 80’s. The high loses control of our weather on Wednesday as it shifts offshore and a cold front will approach the region on Thursday. The chance for showers and thunderstorms will increase by late Wednesday and Thursday before another high pressure system heads our way to close out the week.

Video

httpv://youtu.be/Hq42CwJQCR0

7:00 AM | Nice way to start the new week; amazing day of rain up I-95 yesterday in South Philly

6-Day Forecast

Today

Mostly sunny, comfortable, highs in the low 80’s

Tonight

Partly cloudy, pleasant, lows in the low 60’s

Tuesday

Mainly sunny, still comfortable, low-to-mid 80’s

Tuesday Night

Partly cloudy, mild, mid 60’s

Wednesday

Partly sunny, warm, chance for showers and thunderstorms, mid 80’s

Thursday

Partly sunny, warm, chance for showers and thunderstorms, mid 80’s

Friday

Mainly sunny, warm, mid 80’s

Saturday

Mostly sunny, warm, mid-to-upper 80’s

Discussion

There was a record set late yesterday at Philadelphia International Airport (PHL) in South Philly for daily rainfall when slightly more than 8 inches of rain fell in about a 5 hour period. Just a few miles to the east or west of the airport, however, there was far less rainfall in this highly localized event which was caused by the "training" of thunderstorms when one storm after another passes over the same location. The excessive rainfall at PHL broke the record for the most rainfall in any given day by easily surpassing the 6.63 inches of rain that fell on September 16, 1999 associated with the remnants of Hurricane Floyd. Yesterday's rainfall also pushed the monthly amount of rainfall at PHL to 13.00 inches which is a new record for the month of July. Of course, June was a very wet month as well and the two months are now in second place for rainfall amounts in back-to-back months - still short of the record set in August/September 2011 (remnants of Hurricanes Irene, Lee). By the way, another quarter inch of rain fell after midnight at PHL on top of the 7/28 record amount, and there still is a chance for the wettest summer ever there depending on the August results. Only a trace of rain was recorded yesterday at Reagan National Airport.

A cool front passed through the region late yesterday causing all of this rainfall and high pressure will now fill in behind it controlling our weather for the next couple of days. Temperatures and humidity levels should hold at rather comfortable levels for the next couple of days and it looks rain-free until mid-week at which point another frontal system will threaten the region with showers and thunderstorms.

Video

httpv://youtu.be/nMDfwiuapQA

2:40 PM | Update on Tropical Storm Dorian with near-term prospects for intensification (not great) and potential "subtle, but important" change in the track

Discussion

Tropical Storm Dorian has weakened somewhat over the past 24 hours now with sustained winds estimated at 50 mph whereas this time yesterday the winds were about 10 mph higher. Additionally, the central pressure of Dorian has come up a few millibars (mb) in the past 24 hours to 1006 after being at 999 mb early yesterday. The movement continues to be to the west-northwest (285 degrees) at a rapid clip of 20 mph.

Looking ahead to the next couple of days, there are two things that can be said about the intensification prospects and the storm track. First, it is quite likely that intensification will continue to be inhibited by some more mid-level dry air that is still out ahead of the tropical storm. Second, the current steering winds in the lower part of the atmosphere may make a subtle change to the track from west-northwest to more due west (ie 270 degrees) or even just south of due west (e.g., 260 degrees) and while this may sound insignificant, it could result in the system heading very close to, if not right over, the Caribbean Islands of Puerto Rico and/or Hispaniola. This possible type of track over the Caribbean Islands would likely result in the further weakening or even complete demise of Tropical Storm Dorian. For weak tropical systems, the best atmospheric level to focus on for predicting future storm movement is usually between 850 mb (roughly 5000 feet) and 700 mb (10,000 feet). [The stronger the storm, the more important are the higher atmospheric winds for steering considerations]. Stay tuned.

7:00 AM | Nice weather conditions to close out the week; more humid this weekend with a shower and thunderstorm threat

6-Day Forecast

Today

Mostly sunny, warmer, but still comfortable humidity levels, highs in the low-to-mid 80’s

Tonight

Partly cloudy, mild, lows in the mid-to-upper 60’s

Saturday

Partly sunny, more humid, chance for showers and thunderstorms, low-to-mid 80’s

Saturday Night

Mostly cloudy, mild, chance for showers and thunderstorms, near 70

Sunday

Mostly cloudy, humid, showers and thunderstorms likely, low 80’s

Monday

Partly sunny, comfortable, low 80’s

Tuesday

Partly sunny, warm, mid 80’s

Wednesday

Partly sunny, warm, maybe a shower or thunderstorm, mid 80’s

Discussion

Strong low pressure that formed yesterday along a stalled out frontal system will slam into eastern New England today, but we’ll experience a rather nice day around here with comfortable conditions and plenty of sunshine. The weekend will turn out somewhat unsettled with showers and thunderstorms possible on Saturday and then likely on Sunday as a frontal system approaches the Mid-Atlantic region from the Great Lakes. That front should clear the coast by early next week paving the wave for pretty decent weather to start the new week.

Video

httpv://youtu.be/dqIj5b9W6bo

7:00 AM | Front has stalled along the coast and will keep it cool and somewhat unsettled in the Mid-Atlantic region for today; tropical update

6-Day Forecast

Today

Considerable clouds this morning, some sun this afternoon, cool, chance for showers across the Eastern Shore, highs near 80 degrees

Tonight

Mostly cloudy, cool, lows in the low-to-mid 60’s

Friday

Partly sunny, still comfortable, low-to-mid 80’s

Friday Night

Partly cloudy, cool, mid-to-upper 60’s

Saturday

Partly sunny, warm, more humid, chance for showers and thunderstorms, mid 80’s

Sunday

Mostly cloudy, warm, humid, chance for showers and thunderstorms, mid 80’s

Monday

Partly sunny, warm, mid 80’s

Tuesday

Mostly sunny, very warm, mid-to-upper 80’s

Discussion

A cool front has stalled along the east coast and an area of moisture will ride northward along this boundary zone over the next day or so. Cloudy and cool conditions will prevail in the area this morning and there can be some shower activity over the Eastern Shore, but the afternoon should feature some clearing skies. Temperatures will struggle to climb to the 80 degree mark and then should move into the 80's for highs over the weekend, but still generally below the current normal high temperature of 88 degrees.

Elsewhere, Tropical Storm Dorian continues to churn to the west-northwest in the Atlantic with 60 mph sustained winds and could affect the Bahamas by early-to-mid next week. Beyond that time, there are signs for a curvature in the storm track towards the east coast so this system will continue to be monitored closely.

Video

httpv://youtu.be/viCEw43lzfM

11:45 AM | Depression has been upgraded to Tropical Storm Dorian in the eastern Atlantic

Discussion

Tropical Depression 4 has now been upgraded to Tropical Storm Dorian in the eastern part of the Atlantic Ocean. This tropical wave has become very well organized over the past 24 hours despite encountering some dry air in the middle part of the atmosphere. There is now quite an impressive circulation center associated with the storm and perhaps even an eye trying to form. The 11am measurements have sustained winds at 50 mph, gusts to 65 mph, and movement to the WNW at 20 mph.

While the tropics have been somewhat quiet in recent days, having the fourth named storm on this date is about one month ahead of the average date over the past fifty years (August 23rd), and it is quite rare for a storm to form this far east in the Atlantic this early in the season. In fact, there is a report that since 1851 only three other storms reached tropical storm status this far east in the Atlantic so early in the season (last one was Bertha in 2008). None of the first three tropical storms this season (Andrea, Barry, Chantal) ever reached "hurricane" status. There has not been a major hurricane strike (ie category 3, 4 or 5) in the US since the the record-breaking year of 2005. The 7-year period from 2006-2012 without a major hurricane landfall in the US is the longest period since 1851.

Looking ahead, the next 24-48 hours will be crucial for Tropical Storm Dorian as it’ll encounter some mid-level dry air and slightly cooler waters, but chances are increasing that it will survive this meeting. Models are generally in agreement on moving Dorian to the WNW over the next five days or so and it very well could be near the Bahamas or western Caribbean Islands in about a week or so. Stay tuned - all eyes on the east coast should monitor this new storm.