Is it Dodging or Delaying?

I feel very confident that we have safely passed through the first flooding threat. As I said on the air yesterday, the snowpack before this last storm had between .5" to 1.5" worth of water in it. This past storm brought 1" of rain and if we released all of the snowpack, we would have had some problems. The biggest threat for that in the first storm was in the lower elevations south of I-80. The good news was that the snowpack was cold enough and the rain was cold enough for the snow to absorb the rainfall.

Check out this web page to see the temperature of the snow pack when the storm started on Thursday evening. The red areas were primed to melt, while the white and blue areas were still cold below freezing. Those colder areas ended up primed to absorb the rainfall. Which then just adds to the moisture content waiting on the ground. This means that there is 1.5-2.5" of rainfall stored primed to cause flooding with the next warm rainfall on Monday. Which means that we may have delayed instead of dodging.

Though there is some good news. Now check out this web page to see what the snowpack temperatures were at 11am this morning. The snow has warmed. And that means melting will continue, but without rainfall as most of the precipitation is done. This means that the lower elevations south of I-80 will bleed away some of that water at a safe rate today and then again Sunday with temperatures reaching above freezing. The more that we bleed away, the better we will be when a heavy and warm rainfall comes Monday. That system will cause flooding in some areas. It will be inevitable, but the extent is still unknown. The more we lose until then, the better off we will be.


Of course either way, you should keep an eye on river levels if you live near one. We have redesigned our web page. Check it out: http://wearecentralpa.com/riverlevels

Chief Meteorologist Joe Murgo

The War Has Begun

The war that I am referring to is the war between winter and summer. The war has another name and that is called spring. Often people come to me an state that they can't wait until spring but what they envision as spring and what is truly there are two different things. Spring doesn't really have it's own characteristics but rather is a transition between winter and summer. At first winterlike weather wins out with short bursts of warmth and then slowly summer wins out. We know who wins the war but how it the battles are fought are the day to day patterns of spring. Since the lower levels often start warming faster than the atmosphere above, it is a very cloudy and unsettled time of the year and we are going to see a lot of this over the next couple of weeks.

In fact, we really have started the war and we are going to be right over the major battle zone over the next couple of weeks. In fact, given the La Nina and the cold currently across Canada, I believe the usual spring storms are going to be extra fierce. Will some bring wintry weather. Yes. They usually do. But I also see us sneaking toward 50 with some of these storms cutting to our west. Right now I am seeing the stage set for the potential of heavier rain events that combined with snowmelt may bring a flood potential at one point next week.

--Chief Meteorologist Joe Murgo

Why Saturday Will Not Just be Another Windy Day

Saturday will not just be another windy day in Central PA, as the setup is perfect for some very high winds. The strong gusts could cause damage to trees and power lines, which may lead to scattered power outages. So why is this setup good for exceptionally strong winds?

First, there will be a very tight pressure gradient across the region as we get stuck in between a powerful low pressure system in the Canadian Maritimes and a strong high pressure system located in Central Canada. Big differences in pressure cause strong winds.

The tight pressure gradient happens frequently and gives us windy days, but there is an additional piece of the puzzle that comes into play for Saturday -- the way the winds above the surface are aligned. The jet stream will be sitting overtop of us on Saturday with winds whipping at better than 150 mph up around 30,000-40,000 feet. When those winds align with the winds at the surface, the stronger upper-level winds can enhance some of the gusts here at the surface. With winds being out of the west-northwest at pretty much all levels of the atmosphere on Saturday, that will push what would be an ordinarily windy day (with 40 MPH gusts) to a day where winds could gust as high as 60 MPH.

Also something to keep in mind -- with the air being very dry and the exposed brush and old leaves becoming dry, the threat for brushfires will rise into Saturday. The real threat is the added wind. Any brushfire that starts could spread quickly with those winds gusts of 45 to 60 MPH.

--Meteorologist Brian Thompson

The Highs and Lows of February so Far

The past month has been nothing but a weather rollercoaster. We had temperatures dropping below zero, but we also had temperatures reach 60 degrees! Right now, we are on the longest streak in the past month of temperatures over the freezing mark. For the seventh straight day, we have been above freezing, but only four of these seven were actually above the average high. After the temperature hitting 61 degrees today and tomorrows record high of 61 degrees, there is a chance of surpassing a record! Just a month ago that would have seemed impossible.

Thursday was a whopping 23 degrees higher than the average high, but exactly one month ago the high was eight below the average. The largest gap between actual and average temperatures within the last month occurred today, the second biggest gap was February 10 and January 22 when temperatures dropped 16 degrees below average. From January 17 until the first of February, 14 out of 16 days were below average. On January 24 the low temperature was -5 degrees. Less than one month later, the temperature is up 66 degrees!

Although the past few days have seemed like spring, only 7 days have actually been above average, one was exact, and 8 have been below average since the start of February. Luckily the cold weather was towards the beginning of the month, and it seems to finally be warming after some bitter coldness!

So did Punxsutawney Phil make the right predictions? It sure seems so!

--Weather Intern Julia

Great Time to Work in the Yard

No, I'm not talking about planting anything, but I am talking more than just cleaning the twigs and branches that the wind brought down on the yard during the winter season. Thaws like this are actually a good time to get the pruning done for the upcoming season. Today I trimmed back the grape vines and the bushes that don't already have the buds on them for the spring season. Do be careful though as some plants already have their flower buds set from last fall. Leave this bushes alone until after they flower.

--Chief Meteorologist Joe Murgo

The First of the Magical Snowfall Dates Is Here

February 15th is a milestone when it comes to snowfall. I usually train my interns that once we reach this date, it is hard to get snowfall to stick on the roads during the daylight hours unless the snow comes down at a moderate to heavy rate. Even though there are clouds, the sun is still powerful enough to usually warm the road during the daylight hours so that the crews can keep up with the snowfall. It's also hard to get freezing rain during the daylight hours too. Though keep in mind that constantly shadowed roads can be an exception to the rule of the date.

Because of this higher sun and the resulting effects it is also the time of the year that delays become good enough instead of closings except for major storm systems.

This year the date will mean a lot given that our pattern is now a milder one. By the time the pattern changes back to cold, the harshness of winter will be done.

--Chief Meteorologist Joe Murgo

The Great American Meltdown

The transformation across the nation over the past few days has been quite impressive. On February 10th, 65% of the nation had a snow cover. This was a good bit above average for the date, but a major pattern change occurred and we have seen the snow melt at a very rapid pace. As of this morning (the 14th) we were down to 32% of the nation covered with snow and we will likely see this continue to dwindle later in the week.

Is the threat for all winter over? Absolutely not. Not having measurable snow in March last year was impressive and abnormal. Given it is a La Nina year we will still have some snowflakes and a mix to deal with. Though the back of winter has been broken and by the time we cool down again the chill won't quite have the bite it has had before.

--Chief Meteorologist Joe Murgo

Old Blog Entries

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http://wearecentralpa.com/community/forums/161-stormtracker-weather-blog