Tuesday 9:30 a.m.
The weak storm that moved through the Middle Atlantic states last night provided the first white Christmas in years to parts of Pennsylvania and northern New Jersey. There has been some light snow in southern New England (with rain at the immediate coast).
The next storm will be much bigger and will produce heavy snow to its north and violent thunderstorms to its south. It may be cold enough in the I95 corridor for snow and sleet at the beginning, but most of the precipitation will be rain.
As rapid cooling takes place aloft, we will probably see a band of heavy snow breaking out in eastern Ohio and western Pennsylvania late tomorrow. Farther south, the same cooling may help trigger the violent thunderstorms I mentioned earlier. As the band moves east, locally flooding rain could hit the area between Philadelphia and New York City tomorrow night.
This video has more, including a storm that may have a better chance of snow farther east than with the first storm.
Christmas Day 2012
The Declaration of Independence was signed in the warmth of a Philadelphia summer in 1776; however, as 1776 came to a close, it appeared the revolution might be doomed. George Washington and his forces had suffered a string of losses, and with each loss, there was less and less public support. After all, if the Revolution was lost and the British won, all who participated or aided in the revolt could be tried and convicted of treason against the Crown.
And so, when Washington and his depleted forces dared to cross the icy Delaware River on Christmas night... then cunningly circled around and attacked Trenton from the north with the wind at their backs, sleepy-eyed Hessian defenders waking up on the morning after Christmas were greeted by wind-launched darts and tacks of stinging sleet in their faces and a hail of bullets from the Americans who could hardly be seen through the storm.
The stunning victory at Trenton proved to be the turnaround event that fueled the rebel fire once again. However, that was far from obvious to George Washington as he and his forces recrossed the river and regrouped. The army was about to dwindle away. Enlistments were up at the stroke of midnight, New Year's Eve. Desperate, and without official authorization, Washington called on the soldiers to stay, offering them a bonus if they extended their enlistments. The soldiers did not respond at first, but then one stepped forward, then another... and then another.
They hatched a plan to attack the British once again. Meanwhile, the snow on the ground melted. The rebels crossed the Delaware again on New Year's Day. This time the British were ready, and the rebels were forced into a corner. They were stranded in muddy fields, backs to the river... with no way to escape. One bold attack by the British would wipe out the American forces and end the war.
However, George Washington was a Virginia farmer, and farmers watched the weather. He had experienced winter days with blue skies and northwest winds. He had seen the temperature hold steady during the those days, then sink below freezing at night. He had a thermometer, and at noon it was 39 degrees and holding. A stiff northwest had erased the 50-degree weather of the previous day. Washington ordered the troops to prepare huge bonfires after sundown and make the appearance of bustling around in the camp.
Behind the fire glow, it was dark. We in the age of light pollution are not used to the kind of dark faced every moonless night back in the 1700s. But in the darkness, Washington's troops readied their equipment, even wrapping wagon wheels in cloth to minimize the noise. The ground froze. The forces moved out, picking their way northward... away from the encamped British who were lying in wait to mount their own attack at first light.
Dawn broke to the sight of rebel soldiers marching toward Princeton through fields laced with frost. The Battle of Princeton was fierce but lasted less than an hour. One casualty was General Hugh Mercer. Mercer County, N.J., is named for the fallen patriot. The British were defeated again and pulled back to their garrisons farther northeast in New Jersey. News of the rebel victories spread like wildfire back in Europe weeks later. Soon the French would be emboldened to declare war on Britain and help the American cause. George Washington and his weary forces set up camp in Morristown, N.J., with hills to offer cover and yet close enough to their enemy to spy on their activities.
If George Washington had not been up on his weather knowledge and had not realized it would freeze at night as he did, his forces would have been surrounded and captured the next day. The hard-fought gains at Trenton would have been meaningless.
A vast and empty field marks the place where the Battle of Princeton was fought 236 years before this coming January. As I stood there in an icy wind four Decembers ago, storm clouds were increasing. It was a raw and unforgiving wind, a wind soon to be armed with sleet and freezing rain.
Aside from the wind in the trees, it was silent out there in that field. The darkness was moving in. I closed my eyes for a moment and could almost imagine the footsteps of some of our first war veterans rustling through the fallen, frosted leaves so long ago. And I said a silent thank you. If they hadn't done what they did when they had to, we couldn't do what we want to in freedom... today.
The house in this picture is "The Clark House." Wounded soldiers from both sides were taken here. It was in this house that General Hugh Mercer died several days after the battle.
This upper air map shows (1) there is no strong heatwave ridge over the Midwest or Northeast any more and (2) a broad trough populated with smaller disturbances will move from the Mississippi Valley to the Appalachians by Sunday.
On this satellite picture, we see the plume of moisture advancing northeastward from the Ohio Valley.
In this picture, the sun had set as seen from the ground. However, sunlight was able to light up the clouds from below to create this look outside my home:
Now, drier air has arrived, and most of the Northeast will have abundant sunshine today and tomorrow.
A front that will usher in slightly less humid air for the Northeast tomorrow will trigger locally strong thunderstorms today.
Thunderstorms will continue to erupt near the northern edge of the heatwave, enhanced by a series of disturbances rippling along in the upper air flow. This is the NWS Storm Prediction Center's severe thunderstorm outlook for today