PA Rain Forcefield?

[Swattie87]

Anyone else watching the radar this morning? Was hoping this rain in WV and MD would push north into PA. All morning it reaches the PA line and vaporizes, won't push any further north.

Have a surplus of PTO days due to Covid, and work from home, and was hoping to burn a few this week after some rain. Hopefully it can crack whatever meteorological barrier is sitting right at the PA border and this rain can push north. The whole state needs more than we got out of this last system, especially NC PA.

 

[jifigz]

It is cloudy and cool but not raining here in Mifflin County. It is supposed to rain tomorrow. And there are supposed to be chances of scattered thunderstorms here this afternoon. We will see what happens. Regardless, the trout stream temperatures are cool enough so here in a bit I'm going to go hit the water for a bit and try to tempt some fish to bite.

 

[Bamboozle]

I have ZERO scientific evidence to support it but I have a friend who swears the mystery of disappearing weather systems in his neck of the woods (Scranton/Wilkes Barre) is because of the Waymart Wind Energy Center.

Any big wind farms in the path of those weather systems out there?

 

[sarce]

At a certain point droughts can start reinforcing themselves. The ground can get so dry it actually affects the amount of moisture in the air and can cause precipitation to evaporate. Small storm systems then start tracking around the drought areas but seem to never quite break through. When this happens it takes a large scale weather pattern shift to break the drought. Fortunately, that's underway for western and central PA and there should be a fair amount of rain the next few weeks.

 

[Swattie87]

Bamboozle wrote:
I have ZERO scientific evidence to support it but I have a friend who swears the mystery of disappearing weather systems in his neck of the woods (Scranton/Wilkes Barre) is because of the Waymart Wind Energy Center.

Any big wind farms in the path of those weather systems out there?

There's a lot on top of the ridges in the Laurel Highlands/Allegheny Front, in the general path of some of that rain. Not sure I buy that having any meaningful effect though. The steering currents for weather systems are far higher in the atmosphere than the ridgetop altitudes in PA...Which are only 2000-3000 ft, generally. And over long periods of time (years/decades) you don't notice appreciable precipitation shortages in any specific area that may be associated with wind farms. This would lead me to believe any short term droughts/shortages (like now) are part of normal fluctuation, and/or caused by other factors.

 

[Swattie87]

sarce wrote:
At a certain point droughts can start reinforcing themselves. The ground can get so dry it actually affects the amount of moisture in the air and can cause precipitation to evaporate. Small storm systems then start tracking around the drought areas but seem to never quite break through. When this happens it takes a large scale weather pattern shift to break the drought. Fortunately, that's underway for western and central PA and there should be a fair amount of rain the next few weeks.

I do in theory buy this possibly partially affecting things right now. You see a similar thing with Winter storms. There often is a sharp cutoff, or even a full dry slot within a storm, where the precipitation never reaches the ground due to drier air unable to carry the moisture.

In Summer, a similar phenomenon can cause Tstorms to fizzle out when they get over drier/drought areas. If you've watched radar loops over the last few weeks in NC PA, there have been many instances of pretty good Tstorm activity in northern NY. As the storms have moved S, about over the Finger Lakes, they start to fizzle out, and there isn't much left to them by the time they hit the PA line. NY's USGS streamflow page illustrates this pretty well. Lots of green and light blue along the Canadian border. Lots of orange as you get close to PA, which then transitions to some reds as you get to into Potter/Tioga County PA. That being said, southern PA, where the rain is falling apart now, has not been nearly as dry as NC PA.

 

[tomgamber]

You get that the wind makes the blades turn, not the other way around, right?

 

[UncleShorty]

Stay away from those wind turbines.

There's a stable genius who believes they cause cancer...

 

[Swattie87]

tomgamber wrote:
You get that the wind makes the blades turn, not the other way around, right?

Or do the blades make the wind. :-o Think about it...

Next thing you're gonna try to tell me that the state isn't stocking shorties when I catch those tiny little Trout with the really bright, sharply contrasting spots, and clean edged transparent fins? Riiiiiiight.

 

[tomgamber]

:lol: :lol: int:

 

[troutbert]

https://learn.weatherstem.com/modules/learn/lessons/98/14.html

Here's a map showing average annual rainfall in different parts of PA. There are pretty big differences in different parts of the state.

Looking at the map, you can make some guesses about the causes.

The main weather systems move from west to east across the US.

The high rainfall areas in the Laurel Highlands are probably due to orographic effect on those west to east weather winds. Same thing with the uplands of Cambria County.

That's probably lake effect going east from Lake Erie. Basically a plume of moisture carried off the lake by west to east winds.

In southeast PA you're getting weather coming off the ocean. In Philly, Lancaster Cty etc. there are no mountains between them and the ocean. Places like Tioga and Potter County are much further from the ocean.

Once you go north of Dauphin, into the Ridge and Valley area, you have mountains between you and the ocean.

In the Poconos, there is a lot of rain because of circulation from the ocean, i.e. noreasters, coming across the flatlands of NJ, then getting scraped off by the highlands of the Pocono plateau.

At least, those are my guesses. I never had a college class in weather.

Go ahead weather geeks, whatta you got?

 

[riverwhy]

I was always fascinated by weather growing up. I would stay up most of the night when a storm was hitting, hoping for the day off. We had a huge PA Atlas at the library. I bet it weighed over 5 pounds. I would study all the maps and learn county, climate, rainfall, snowfall terrain, forest cover, land use, rivers, etc. This was before the days of google maps. When I went off to Penn State I loved watching weather world. My mom and dad could always expect a call from me when it was snowing up in State College. I don't know why I loved it so much and still do. My family makes fun of me when I say, "Did you see it snowed in Bradford today? i have a friend who has a Cabin in Shunk (He loves the weather too) and its funny how he has mentioned a couple of times this summer storms have missed Shunk. Now that I look at the map I can see it is already a pattern!

Troutbert's assessment looks on the money. One thing I remembered from some more detailed maps is that the east faces of the ridges in the ridge and valley get less precipitation than the west. That reflects the prevailing westerlies and the wringing out of the moisture by orographic forcing. Some areas that have me curious:

The hole in Warren County.
The heavier areas around Mifflin, Centre, Snyder, Union counties.
The hole on the lower Susquehanna along the Lancaster/York Border (Chesapeake?)
The really high amounts on the Berks/Schuylkil line(must be closest real mountains to the Atlantic?)

One local pattern I have noticed here in Hershey is that if a line of storms forms west of us it almost always splits with heavier rainfall in Central-Northern Dauphin. and some heavier rain south into Lancaster County. Sometimes it seems to follow the river down to Mount Joy.

There are more detailed maps on precipitation you can find. I will post one if I can. I remember looking at seasonal maps in the past as well as snowfall maps.

 

[GeneBeam]

You also need to look that the leeward and windward sides of the mountains. If a rain system is coming from the west that most of the rain will be rung out of the storm as it goes over the mountains and the windward side of the mountain will get most of the rain while the leeward side will get less.

This is more prevalent out in the western US with the Sierra, Cascade and Rocky mountain ranges as they are much higher in elevation then the Appalachians.

As the warm most air of a rain system gets pushed up the side of a mountain the air turns cooler and moisture in the air condenses and rain. But unlike the Sierra and Cascade mountain ranges which almost always get weather systems coming from the west or northwest, here in Pennsylvania we can get weather systems coming from almost any direction, but mostly from the west & southwest in the summer and west and northwest in the winter and from the south or east with Hurricanes or nor’easters. That could be the reason for the rain pattern in the Poconos with storms coming from the east or southeast and the Blue Mountains in southcentral pa with storms coming mostly for the west or southwest.

As for snow we all know about lake effect snow. So the north western part of PA gets that just like northern Ohio and the Keweenaw Peninsula and southern shores of Lake Superior in the UP of Michigan and the western LP of Michigan.

But why so little average rain in Tioga & Bradford and some of the far west counties in PA? The valleys in southcentral PA I can understand, as every time a weather system goes over a mountain more moisture gets rung out, so each valley from west to east get less rain.

 

[Swattie87]

This stuff fascinates me too. If I better understood what my life’s interests would be at age 18 than I did, I would have studied meteorology. No question.

I think you guys are largely on point with your explanations/observations about the precip map tb posted. Great map by the way.

A couple additional thoughts...

1. It’s a detailed map. The difference between each shade in color is only a 2” range over a whole year. Differences of a shade or two aren’t all that significant, relatively speaking.

2. Is this all precip, or just rain? Meaning does it include snowfall amounts, converted to rainfall? Snow can have varying amounts of moisture content to it, so it can vary, and 1” of snow does not equal 1” of rain. It can be 10:1 sometimes. Anyway, precip is clearly heavier at the higher altitude locations in PA...Poconos, Endless Mountains, Ridge and Valley ridgetops, Laurel Highlands, Allegheny Front, etc. In snow events it’s very common for ridgetops to get far more snow than their surrounding valleys. Sometimes a ridgetop at 2000 ft plus of elevation will have several inches of snow, and the surrounding valley floor at 1000 feet will have very little, if any. Especially in moisture starved Winter storms like clippers. There can be a big difference. Moisture rich nor’easters have less variance, though higher elevations still get more. I think the same happens with rain and altitude, though also not as big of a difference.

3. While we love them, keep in mind that the PA Appalachians are very small by mountain standards. While I certainly think they can influence weather on a very localized basis, their altitudes don’t require a great deal of lifting for weather systems traversing them, and the steering currents for weather are far above them. Most PA mountain ranges top out between 1600 and 2500 ft in elevation. A handful get a little higher, generally along Laurel Ridge and the Allegheny Front. The typical drop in temperature from a valley at 1000 ft to a ridgetop at 2500 ft is only 5 or 6 degrees, if that.

4. The relative drop off in precip just east of the Allegheny Front (Blair/Bedford/Huntingdon/Fulton counties) is likely the influence of the three major mountain ranges to their west...Chestnut Ridge, Laurel Ridge, and the Allegheny Front, moving west to east. They are all 500-1000 ft higher in elevation than the ridge and valley tops to their east. (This is probably the best evidence of a somewhat broader scale mountain effect in PA. Though it only results in a 15% or so difference in precip over the course of a year. Larger mountain ranges will have a much larger effect.)

This turned out to be a great thread! Keep it coming!

 

[tomgamber]

I spent a lot of time (during my tv days) talking to weather guys in the studio. Usually about what my chances were of having decent weather if I go fishing here or there.

Most, of them, unfortunately, got their meteorology (sp) degrees via mail from Mississippi state. Most do. But every once in a while I would come a cross a guy who knew his stuff and it is fascinating.

It was a lot more interesting in Idaho having to deal with the elevation changes and extreme difference between which direction any given system might approach but even here in Pa with closer proximity to the ocean driven systems its hard to predict with any hint of certainty, much more than 18-24 hours out.

They know this and will admit it. But people demand more so they give it to them. And then they giggle a little when people complain how "wrong" they were.

 

[wildtrout2]

I'm wondering what kind of long term effect these drought conditions might have on a lot of the NC streams that are now basically dry, except for the deepest pools? I don't recall seeing it this bad up there.

 

[gulfgreyhound]

Maybe help is on the way? Long windy ,rainy Sally may make a favorable turn. Here it's windy and rain like a cow on a flat rock. GG

 

[Swattie87]

Conditions are roughly equivalent to 2016 across Potter/Tioga/Clinton/Lycoming. I was up there in the worst of it that year. Kettle (at Cross Fork) was flowing at 4 CFS (currently 6 CFS). Most streams were trickles, but still continuously flowing. Some had brief stretches that were sunk. The fish were stacked in pools, and exceptionally spooky, but there were plenty alive.

I recall generally slow fishing up there in 2017, the year after the drought conditions. But very good fishing in 2018 and 2019, both wet Summers, but not that far removed from a drought year. I haven’t fished up there much this Summer, but the wild Trout fishing was relatively good the one trip I made in June. One stream in particular fished very well, and I caught many 8-10” wild Browns and actually decided to keep two for dinner one night...A decision I now regret given how the conditions have panned out this Summer.

I think you can probably expect a down year or two from this, but as long as we don’t get a couple bad rainfall Summers in a row, I think the overall effect will be relatively short term. Trout mature relatively quickly, and at a fairly small size. As a result their populations can really yo-yo year to year.

 

[Dave_W]

Swattie87 wrote:
Conditions are roughly equivalent to 2016 across Potter/Tioga/Clinton/Lycoming. I was up there in the worst of it that year. Kettle (at Cross Fork) was flowing at 4 CFS (currently 6 CFS). Most streams were trickles, but still continuously flowing. Some had brief stretches that were sunk. The fish were stacked in pools, and exceptionally spooky, but there were plenty alive.

I recall generally slow fishing up there in 2017, the year after the drought conditions. But very good fishing in 2018 and 2019, both wet Summers, but not that far removed from a drought year. I haven’t fished up there much this Summer, but the wild Trout fishing was relatively good the one trip I made in June. One stream in particular fished very well, and I caught many 8-10” wild Browns and actually decided to keep two for dinner one night...A decision I now regret given how the conditions have panned out this Summer.

I think you can probably expect a down year or two from this, but as long as we don’t get a couple bad rainfall Summers in a row, I think the overall effect will be relatively short term. Trout mature relatively quickly, and at a fairly small size. As a result their populations can really yo-yo year to year.

I've not been up that way this year but I agree with your observations about wild trout stream cycles. The turn over and up/down population cycles of small trout streams can be highly variable year to year and I think sometimes a dry or drought year gets folks a bit more concerned than necessary.

 

[troutbert]

If you walk along these streams during droughts, or even during seasonal low flow periods, you can really see the importance of good "holding water" for trout, i.e. pools and cover.

In severe droughts like this, the pools are the only places where trout can survive. In between the pools there is precious little water.

A 12 inch trout can't live in water that's 1/2 inch deep.