Arctic Front: Late Arrivals

By: Lee Grenci, 6:19 PM GMT on February 24, 2015

A good question from George about the late arrival of Arctic air in the DC area on Monday, February 23:

On a peripherally related note, do you have any thoughts on the delayed arrival of the arctic air here. It seemed to get hung up in the mountains for several hours which is typical, yet often missed. I was too busy with other things to be watching it but local forecasters were fast with its arrival (predawn rather than the verifying rush hour timing).

Synoptic Meteorology

Updated: 12:50 PM GMT on March 02, 2015

Blankets, Trapping, and Re-Radiating: Cringing in Central Pa.

By: Lee Grenci, 4:25 PM GMT on February 21, 2015

For much of my professional career, I have been a proponent for using concise language that conveys sound scientific principles to the general public. I have long believed that meteorologists who take shortcuts in language are a heartbeat away from stepping over the line that separates science from what I have described in the past as "disinformation." It doesn't matter what people think about my attitudes toward concise language in meteorology. In my book, scien...

Radiative Transfer

Updated: 3:09 PM GMT on February 23, 2015

Misleading Snowfall Forecasts

By: Lee Grenci, 4:06 PM GMT on January 27, 2015

In my opinion, there was uncertainty in the Philadelphia / New York City snowfall forecasts that forecasters did not openly convey to the public.

When I was teaching forecasting at PSU, I always warned my students not to get caught up with "choosing the model of the day," especially in times of uncertainty. In such situations, a probabilistic, multi-model ensemble forecast (a "blend" of computer simulations) is best. I understand that the public want and...

Updated: 4:23 PM GMT on January 27, 2015

It Never Ends, Second Call...

By: Lee Grenci, 7:51 PM GMT on January 11, 2015

A friend of mine just sent me this link to a write-up of the recent record high pressure over the Upper Middle West.

Read the first sentence of the fourth paragraph. "High pressure occurs when air sinks, which exerts a downward force on the ground." According to this absurd reasoning, which purports that sinking air exerts great pressure when it "hits" the ground, surface air pressure must be zero if the air moves upward away from the ground. Yeah, righ...

Synoptic Meteorology

Updated: 9:31 PM GMT on January 11, 2015

It Just Never Ends...

By: Lee Grenci, 7:03 PM GMT on January 08, 2015

Last night on the CBS evening news, a reporter talked about farmers in South Carolina covering their plants to "protect them against frost." It still really bothers me to hear people on television suggest that frost kills or damages plants.

Have you ever seen orchard owners spraying their plants on cold nights to protect them? Naturally, the spray eventually turns into's essentially frost gone wild!!! Are these orchard owners crazy? Facing the de...


Updated: 7:03 PM GMT on January 08, 2015

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About 24hourprof

Retired senior lecturer in the Department of Meteorology at Penn State, where he was lead faculty for PSU's online certificate in forecasting.