7:00 AM | Stays unsettled as approaching cool front brings threat for showers and storms

6-Day NYC Forecast

Today

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

Tonight

Slight chance for showers and thunderstorms this evening; otherwise, becoming partly cloudy, mild, lows in the upper 60’s

Thursday

Mostly sunny, warm, rather humid, low 80’s

Thursday Night

Slight chance for showers and thunderstorms; otherwise, mostly cloudy skies, mild, mid 60’s

Friday

Partly sunny, a bit cooler, rather humid, chance for showers and thunderstorms, near 80 degrees

Saturday

Mainly sunny, warm, low 80’s

Sunday

Mainly sunny, warm, low-to-mid 80’s

Monday

Mainly sunny, warm, low-to-mid 80’s

Discussion

Low pressure over the Great Lakes region will push a cool front our way later today and it is likely to spark a few scattered showers and thunderstorms in the Mid-Atlantic region. The cool front will then stall out to the south and east of the I-95 corridor and this close proximity will keep the weather somewhat unsettled later in the week, but the weekend is looking pretty nice.

7:00 AM | Much more comfortable today, but shower/storm threat returns quickly...remains of Tropical Storm Bill could play a role in our weekend weather

6-Day Philly Forecast

Today

Partly sunny, pleasantly warm and far less humid, highs not far from 80 degrees

Tonight

Becoming cloudy with a chance for showers and thunderstorms, mild, lows in the low 60’s

Thursday

Mostly cloudy, not as warm, more humid, showers likely primarily in the morning, maybe a thunderstorm, mid 70's

Thursday Night

Chance for showers and thunderstorms, mild, muggy, mid 60’s

Friday

Partly sunny, warm, humid, chance for a shower or thunderstorm, mid 80’s

Saturday

Partly sunny, warm, chance for rain and and thunderstorms late in the day or at night depending on the movement of the remains of Tropical Storm Bill, near 80 degrees

Sunday

Mostly cloudy, quite warm, humid, chance for rain and thunderstorms depending on the movement of the remains of Tropical Storm Bill, mid-to-upper 80’s

Monday

Partly sunny, quite warm, humid, chance for showers and thunderstorms, mid-to-upper 80’s

Discussion

A cool front passed through the area late yesterday and much more comfortable air has pushed into the Mid-Atlantic region. This break in the overall active weather pattern will not last too long; however, as the front will return northward as a warm front later today and tonight and this will renew the chances for rain and thunderstorms. It’ll stay somewhat unsettled later tomorrow and on Friday as well with the chance for a shower or thunderstorm and then attention will turn to the impressive moisture field associated with Tropical Storm Bill which has pounded Texas with heavy rainfall. This area of moisture is likely to get pushed to the north and east over the next few days by upper-level winds and it could very well generate some heavy rainfall in the Mid-Atlantic region late Saturday into Sunday.

7:00 AM | *More heavy rain and possible flash flooding*

6-Day Philly Forecast

Today

Mostly cloudy, cooler with additional showers and thunderstorms, the rain will be heavy at times with flash flooding possible, highs in the mid-to-upper 70’s

Tonight

Cloudy and cool with more showers and thunderstorms, the rain will be heavy at times with flash flooding possible, lows near 60 degrees

Tuesday

Mostly cloudy skies, cool with lingering showers and thunderstorms likely primarily in the morning, upper 60’s

Tuesday Night

Chance for evening showers; otherwise, mostly cloudy skies, cool, low-to-mid 50’s

Wednesday

Partly sunny skies, comfortable, cannot rule out a shower or thunderstorm, low 70’s

Thursday

Mostly cloudy skies, pleasant, cannot rule out a shower or thunderstorm, low-to-mid 70’s

Friday

Mostly cloudy skies, a bit warmer, chance for showers and thunderstorms, upper 70's

Saturday

Partly sunny skies, warm, chance for showers and thunderstorms, near 80 degrees

Discussion

Waves of low pressure are riding along a frontal boundary zone that is slowly working its way through our area. As a result, in the transition to a cooler weather pattern, showers and thunderstorms will continue into Tuesday and some of the rain will be heavy at times with possible flash flooding. Most locations along the I-95 corridor from DC-to-Philly-to-NYC will see an additional 1.50 to 3.00 inches of rainfall in the next 24 hours or so on top of last night's soaking rains with localized amounts of 4+ inches possible. The second half of the work week will feature some improvement and pretty comfortable temperatures, but a shower or thunderstorm cannot be ruled on any day between Wednesday and Friday.

Video

httpv://youtu.be/L19kFFWwnkk

10:00 AM | 2015 Tropical and Mid-Atlantic Summertime Outlooks

Discussion

Overall Summary

The overall numbers are likely to be down this year in terms of the number of Atlantic Basin tropical storms, but the sea surface temperature pattern in the western Atlantic and Gulf of Mexico makes the U.S. east coast vulnerable to “home-grown” tropical hits. The major factors involved with this year’s tropical outlook include a strengthening El Nino in the central equatorial Pacific, colder-than-normal waters off of the west coast of Africa, and pockets of warmer-than-normal temperatures in the Gulf of Mexico and also just off the US east coast. As a result, there are likely to be fewer-than-normal “African-wave” type tropical systems that travel long distances across the tropical Atlantic this season and more in the way of “home-grown” type systems that develop much closer to the U.S. Typically, the “African-wave” type storm plays an important role during the peak months of the tropical season (August and September) while “home-grown” systems can be important early and late in a given tropical season.

In a normal Atlantic Basin tropical season, there are about 12 named storms with 6 or 7 reaching hurricane status and only 2 or 3 actually reaching major status (i.e., category 3, 4 or 5). This year there may be more on the order of 8-10 named storms with 3-5 reaching hurricane status, but despite these expected slightly below-normal overall numbers, the U.S. could actually see more tropical activity than normal due to the sea surface temperature pattern in the western Atlantic and Gulf of Mexico.

One final note of interest, amazingly and fortunately, the US mainland has not been struck by a major hurricane (i.e. category 3 or higher) since Hurricane Wilma in October 2005. Although the landfall record gets muddy before the early 20th century, this is the first time since hurricane record-keeping began in 1851 that the United States has gone so long without at least a category 3 landfall. The previous streak was eight years, from 1861 to 1868.

El Nino in the tropical Pacific Ocean

What goes on in the tropical Pacific Ocean does indeed have an effect on the tropical Atlantic Ocean. El Nino, which refers to warmer-than-normal waters in the equatorial Pacific Ocean, affects global weather patterns and it tends to produce faster-than-usual high-altitude winds over the tropical Atlantic Ocean. This increase in the upper atmospheric winds over the tropical Atlantic Ocean is usually an inhibiting factor for tropical storm formation in the Atlantic Basin as it tends to “rip apart” developing storms. Currently, there are numerous signs for strengthening of the current El Nino in the tropical Pacific Ocean over the next few months and this should inhibit storm formation in the tropical Atlantic Ocean. Specifically, numerous computer forecast models support the idea that the current relatively weak equatorial El Nino strengthens this summer into moderately-strong status.

[Computer model forecasts of El Nino; courtesy IRI, Columbia University, NOAA]

Atlantic Ocean, Gulf of Mexico sea surface temperature patterns

The main breeding grounds for Atlantic Ocean tropical systems are in the region between the west coast of Africa to the Caribbean Sea and the Gulf of Mexico. Above normal sea surface temperatures in this region generally help to intensify tropical waves that come off of the west coast of Africa and move westward in the trade winds. Similar to last year, there is a pocket of colder-than-normal sea surface temperatures off the west coast of Africa and this should inhibit the formation of tropical storms in that part of the tropical Atlantic Ocean. On the other hand, there are warmer-than-normal pockets of water just off the U.S. east coast and across much of the Gulf of Mexico, and these anomalous regions should aid in the development of “home-grown” type storms in nearby locations such as the Caribbean Sea, Gulf of Mexico or just off the Southeast U.S. coastline. [Sea surface temperature anomaly pattern (orange, yellow = warmer-than-normal; courtesy NOAA]

Mid-Atlantic Summer Outlook

I believe there is little chance for a hot, dry summer in the Mid-Atlantic region and the most likely scenario is for near normal rainfall amounts with a slight leaning towards the cool side of normal when it comes to temperatures in the June, July, August time period The strengthening of El Nino in the tropical Pacific Ocean will play a role in our summertime weather pattern which usually leads to cooler-than-normal conditions, and there are two other factors that should turn out to be meaningful. First, the record-breaking Great Lakes ice cover extent during the past winter season is generally a useful predictor of cooler-than-normal temperatures in the Mid-Atlantic region during the subsequent summer season. In fact, Great Lakes ice cover extent as of late April was 27% - the highest ever so late in the season – and there was still more than 5% coverage in early May across Lake Superior. This finding of generally cooler-than-normal summers in the Mid-Atlantic region following high ice cover winters in the Great Lakes region is not necessarily because of the actual ice cover, but rather due to the overall - and likely still on-going - weather pattern that created the anomalous ice cover in the first place and typically persists beyond the winter season. In addition, soil moisture content is relatively normal around here in the Mid-Atlantic region as we head into the month of May thanks to the snowy winter and recent spring rains. Normal-to-high soil moisture content tends to significantly reduce chances for summertime drought and excessive heat.

Paul Dorian

Vencore, Inc.

Extended Video Discussion

httpv://youtu.be/x8QZ3wxVGJM

7:00 AM | Above normal temperatures for much of the week

6-Day Forecast

Today

Mostly sunny, cool, highs near 50 degrees

Tonight

Partly cloudy, cold, lows by morning in the upper 20’s

Tuesday

Partly sunny, milder, low-to-mid 50’s

Tuesday Night

Mostly cloudy, cold, near 30

Wednesday

Partly sunny, mild, near 50

Thursday

Mostly sunny, mild, low-to-mid 50’s

Friday

Mostly sunny, quite mild, upper 50’s

Saturday

Mostly sunny, mild, mid 50’s

Discussion

An upper level ridge will build into the region this week and this will generate a warming trend with downsloping flow that will keep us above normal “temperature-wise” for much of the week.

7:00 AM | A mild start to the new week

6-Day Forecast

Today

Mostly sunny, warm, highs in the low-to-mid 70’s

Tonight

Mostly clear, cool, lows near 50 degrees

Tuesday

Mostly sunny, cool, mid 60’s

Tuesday Night

Partly cloudy, chilly, near 50

Wednesday

Mostly sunny, cool, upper 60’s

Thursday

Mostly sunny, milder, low 70’s

Friday

Mostly sunny, cool, near 70

Saturday

Mostly sunny, pleasant, low 70’s

Discussion

After a mild start to the week, a weak system will pass through the region tomorrow and usher in slightly cooler air for the middle part of the week.

7:00 AM | Mild as we close out the week

6-Day Forecast

Today

Mostly sunny, warm, highs in the upper 50’s

Tonight

Partly cloudy, cold, lows by morning in the low 30’s

Saturday

Partly sunny, breezy, not quite as mild, low 50’s

Saturday Night

Mostly cloudy, cold, maybe a few snow showers, low 20’s

Sunday

Partly sunny, colder, upper 30’s

Monday

Mostly sunny, milder, upper 40’s

Tuesday

Mostly sunny, even milder, mid 50’s

Wednesday

Mostly sunny, mild, low 50’s

Discussion

An upper level trough will move overhead today causing breezy and milder conditions in the region. A weak disturbance from the Pacific Northwest will push a cold front across the area this weekend and temperatures by Sunday will be down considerably than where they will end the work week later this afternoon.

Video

httpv://youtu.be/ssP47o-nFlA

7:00 AM | A little cooler this weekend, but an overall decent weather pattern

6-Day Forecast

Today

Mostly sunny, pleasant, highs in the mid-to-upper 70's

Tonight

Mostly clear, cool, lows in the lower 50’s

Saturday

Mostly sunny, pleasantly cool, low 70's

Saturday Night

Partly cloudy, chilly, near 50

Sunday

Mostly sunny, nice, low 70’s

Monday

Mostly sunny, pleasant, low 70’s

Tuesday

Mostly sunny, cool, near 70

Wednesday

Mostly sunny, pleasantly cool, near 70

Discussion

An upper level trough will cool temperatures slightly for the weekend, but then a milder trend will take place early next week.

Video

httpv://youtu.be/ssP47o-nFlA

12:00 PM | Weather and the Battle of Trenton on December 25-26, 1776

Discussion

Morale was low, hope for winning the war was diminishing, and the cause for independence was fading in December of 1776. The Continental Army led by George Washington was thinning in numbers after many battles lost to the British. December began with lots of rain and muddy travel conditions for the men which did not help with their spirits. After retreating through New Jersey, they set up camp in Valley Forge, Pennsylvania where the army was met with very cold weather that led to plenty of ice on the Delaware River. All in all, things were not looking good for Washington's army.

However, George Washington devised a plan that would change the course of the war and the history of our nation. With only a week before his soldiers' enlistments expired, Washington had to do something fast. He decided he would attack Trenton, New Jersey, which the Hessians (German soldiers fighting with the British) controlled. He planned to cross the Delaware River on Christmas Day and invade Trenton before sunrise on December 26th. Washington thought this action could catch the Hessians off guard and create a better possibility of victory, thereby boosting the morale of his army.

So the day came, Christmas 1776. The weather was actually quite tranquil for most of the day. The morning started off with a mixture of sun and clouds, very cold temperatures in the upper teens, and light northerly winds. By the afternoon, clouds started to increase with temperatures now peaking in the upper 20s. These clouds were associated with a powerful nor’easter that was rapidly strengthening off the coast. This storm brought freezing rain to the Delaware Valley that then changed to sleet and snow. The crossing of the river began at 5pm on the 25th with temperatures in the upper 20s. As the 2,400 soldiers, 18 cannons, and 75-100 horses crossed the Delaware, they had to deal with the icy river conditions. During the crossing, one of the soldiers described the weather conditions as a “violent storm of rain, hail, and snow [the nor’easter] coupled with the ice flows and high winds, slowed operations.” Meanwhile, George Washington patiently watched his soldiers implementing his dramatic plan in these extreme conditions. One of his officers wrote, “He [Washington] stands on the bank of the stream, wrapped in his cloak, superintending the landing of his troops. He is calm and collected, but very determined. The storm is changing to sleet and cuts like a knife.” All the men finished crossing the river at 3am on the 26th, 3 hours behind schedule due to the weather and sheets of ice on the river. The plans to attack under cover of darkness were ruined, but Washington and his men marched to Trenton anyway, undeterred by the conditions.

Temperatures were now in the low 20s with wind driven snow and sleet coming down as the march continued to Trenton. Many soldiers were suffering and one even froze to death during the 9 mile trek. At 8 AM, hidden by heavy snow, the surprise attack on the Hessians began. Although the sleet and snow provided cover, it also made many of the muskets misfire, so cannons and bayonets were used by Washington’s forces. Washington’s plan had worked and the American army captured 900 Hessians with only a few revolutionary troops wounded. Trenton had been taken and the fight for Independence would survive.

In the end, Washington and his army endured the extreme weather conditions and the weather conditions helped with the surprise attack since the Hessians did not expect an assault in such weather. This is now thought of as the turning point in the American Revolution and another example of how weather influenced history.