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Central PA...February ends, March begins...


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Nice! Looks like Centre County was the beast of the area. Good luck later this week.... may get ugly if we don't stay cad'd long, or don't see a fast changeover like this one.

Well I think the changeover to snow helped us out with some flooding issues. I see most of the streams and the West Branch of the Susquehanna. Has crested a couple feet less than they was first predicted.

But just wondering if the snow will bite us in the butt with this next event. Definitely something to factor in I would think. :popcorn:

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Hi All...

(Jamie...great pix, especially the ones with the deep blue sky in the background!)

Here are the final stats from the storm for me here in Carlisle...

Total liquid from all rain, sleet, and snow = 1.96"

Total frozen precip (mostly snow) = 2.1".

Not quite sure how much pure rain before the frozen began, but I'm thinking around 1.80" or close to that. I know that CXY airport recorded around 2.3" of liquid for the storm so I seem to be in line.

The gradient was pretty amazing from south to north...even within my own county. Jon got twice as much snow I did. He is about 20 miles east-northeast of me. The northerly component seems to have made much of the difference.

That's it for now. I'll be back with rain updates later this week.

---Stephen

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Hi All...

(Jamie...great pix, especially the ones with the deep blue sky in the background!)

Here are the final stats from the storm for me here in Carlisle...

Total liquid from all rain, sleet, and snow = 1.96"

Total frozen precip (mostly snow) = 2.1".

Not quite sure how much pure rain before the frozen began, but I'm thinking around 1.80" or close to that. I know that CXY airport recorded around 2.3" of liquid for the storm so I seem to be in line.

The gradient was pretty amazing from south to north...even within my own county. Jon got twice as much snow I did. He is about 20 miles east-northeast of me. The northerly component seems to have made much of the difference.

That's it for now. I'll be back with rain updates later this week.

---Stephen

Stephen, and just over the other side mountain from me (big hill) in Marysville (Perry County) they had 51/2 and 6". Thats prob. around a mile differnce. Crazy!

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Tony

May 7th....sheesh

I was curious how much did you end up getting out of this mess?

I am also looking forward to your input on this next storm.

This was a bad throwing snow, once the sun come out. Snow wanted to clog up the augers.

I have been blowing snow a lot of years and only about the 2nd time that has happened.

Come on man, some of us have high school softball seasons to squeeze in before then...:whistle:

I know. I'd love to have a spring like last year.

With so much cold air lurking north of the border, the nao dipping into negative values at times and the pna doing the opposite, we may be in for a long haul out. I wouldn't be shocked if we were still getting advisories and warnings for another 30 to 40 days for snow.

I ended up with around 3 to 3.5" with this one. Like you said, it was quite heavy and wet - lots of water. Could be an issue later this week if we don't change over fast.. The new euro is suggesting some front end snow like the nam, and some on the back too.

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Okay, here's an honest question...what would a 3" to 4" rainfall in the Susquehanna river basin do to the river based on where it should be going in to the storm? Would that produce minor, moderate, or severe flooding?

And how is that predicted?

I would say Mod-Major. NWS has some program where they put in numbers and makes a forecast.

Here is what HPC has.

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Geez, I'm getting worried for folks that live along the river. Some anxous days ahead for sure.

The ground here is like a swamp. If we get over 2" all I can do is laugh. The creek near my house is scraping flood stage and is not really supposed to fall before the rain starts.

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Euro on next storm total QPF

184699_205816599435216_203514829665393_863880_864407_n.jpg

This is what the Euro is predicting. Which has the highest QPF of the GFS, Euro and Nam? How do we know the Euro is not over doing QPF like the Nam was for this last storm? I'm thinking that's a lot of rain/snow. Rather than just show one model.

It would make sense to combine the 3 and come up with a happy medium that way.But that is just my thought.

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This is what the Euro is predicting. Which has the highest QPF of the GFS, Euro and Nam? How do we know the Euro is not over doing QPF like the Nam was for this last storm? I'm thinking that's a lot of rain/snow. Rather than just show one model.

It would make sense to combine the 3 and come up with a happy medium that way.But that is just my thought.

That's what hpc does. Their map is above.

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Okay, here's an honest question...what would a 3" to 4" rainfall in the Susquehanna river basin do to the river based on where it should be going in to the storm? Would that produce minor, moderate, or severe flooding?

And how is that predicted?

Here's a good place to start...

http://water.weather.gov/ahps/

Copied from one of the links on this page -

"A Brief Overview of the NWS Precipitation and River Forecasting and the River Forecast on the AHPS Hydrograph

How does AHPS use precipitation observations and forecasts in its river models to produce river forecasts?

The National Weather Service (NWS) uses river forecast models to estimate the amount/level of water flowing through the US Rivers. These models estimate the amount of runoff a precipitation event generates, computes how the water will move downstream, and then predicts the flow of water at a given location (AHPS forecast point) throughout the forecast period (every six hours, out 3 to 5 days in many locations).

As the precipitation event unfolds and actual reports of precipitation amounts from rain gauges and radar estimated rainfall become available, the precipitation forecast values are replaced with the observed amounts in the river model. For an ongoing precipitation event, the river model will use both observed and forecast precipitation amounts to predict the river levels. In addition to precipitation, some other factors the NWS River Models account for are: snowmelt, base flow/groundwater, reservoir operations, and routed water from upstream.

This discussion on river models provides the background information on the river forecasts provided on the AHPS hydrograph. Additionally, it’s beneficial for AHPS users to understand the process of issuing river flood watches and warnings.

E

very morning, hydrometeorologists at the NWS River Forecast Centers (RFCs), collect and quality control precipitation observations and precipitation forecasts. Depending on the particular weather scenario and the forecaster confidence in the precipitation amounts forecasted (timing, location and total volume), forecasters will use anywhere from 6 to 48 hours of forecast rainfall. RFC hydrologists enter these data into their river models. Model output is examined and adjusted to produce the best forecast possible. The river forecasts at each AHPS location are sent to the NWS Weather Forecast Offices (WFOs), who in turn issue flood watches and warnings to the public.

What does this look like on the AHPS hydrograph pages?

On occasion an AHPS hydrograph will show the river forecast going above flood stage, but no river flood watch or warning is issued by the NWS. Typically, this indicates significant forecast uncertainty. In this case, AHPS users should routinely monitor NWS web pages, NOAA Weather Radio and stay alert to the changing conditions.

As confidence in the forecast increases, forecasters will issue watches and/or warnings. A flood watch indicates that there is still some uncertainty in this forecast. AHPS users should utilize the AHPS hydrographs and the NWS flood watch information to make appropriate decisions to protect lives and property. In this case, AHPS users should routinely monitor NWS web pages, NOAA Weather Radio and stay alert to the changing conditions. Forecasters will either issue flood warnings if confidence in the forecast increases, or allow the watch to expire.

A flood warning issued by the NWS means that forecasters have significant certainty in this forecast. AHPS users should utilize the AHPS hydrographs and the NWS warnings to make appropriate decisions to protect lives and property.

In all cases, the AHPS river forecasts and NWS watches/warning may be updated at any time with new forecast information.

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Fetus

Good post!!

Something else to look at is how much water the flood control dams are currently holding.

Thanks (I think). Get a little twitchy when the Fetus term makes an appearance.:thumbsdown:

But seriously, that article just shows how much our friends at the NWS have going on at any given moment.

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Okay, here's an honest question...what would a 3" to 4" rainfall in the Susquehanna river basin do to the river based on where it should be going in to the storm? Would that produce minor, moderate, or severe flooding?

And how is that predicted?

To further on Festus post, I actually put this on late sat night/sun morning when I threw on a disco about the now departing storm, but you can also go here, http://www.srh.noaa.....php?pil=FFHPA2

That is the headwater flood guidance printout for each of the flood categories in the headwaters that feed into the Susquhanna and Delaware Rivers. I'll use a local river as an example.

: Little Juniata River...

SPKP1 0.7/ 0.8/ 1.0/ 1.1 :Spruce Creek (8ft.)

:SPKP1md 1.1/ 1.2/ 1.6/ 1.8 :Spruce Creek (10)

:SPKP1mj 2.0/ 2.4/ 3.0/ 3.6 :Spruce Creek (14)

The numbers from left to right are how much rain would need to fall in a 1hr, 3hr, 6hr, and 12hr period to start flooding in each of the categories (minor, moderate, major) based on the flood criteria of that particular station.

Here is another link which is flash flood guidance values, which goes by county.

http://www.srh.noaa.....php?pil=FFGPA2

This is the amount of rain that needs to fall to start small stream flooding.. i.e the flood advisories that get issued. And the values for each county once again go for rainfall need over 1hr, 3hr 6hr, and 12hr to start flooding.

Now to comment on the values that are in there today. These guidance values are obscenely low compared to what you would usually see in the summer and fall if its farily dry, and they probably won't improve too much in the next couple days before it rains again. A 3-4 inch rainstorm in the fashion the Euro has it today in the Susquehanna basin would likely be hands down a widespread major flooding event for most/all tributaries and probably the Susquehanna itself. Even more concerning is the new snowfall that has fallen in the upper Susquehanna valley and on up into BGM's region. Not sure if you guys checked the PNS for up there, but there are widespread reports of 20+ inches of snow that fell from last nights storm. I'm not ready to buy into that widespread of an area of such excessive rainfall.. but even an inch or two of rain coupled with enough warmth to release at least a significant portion of that snowpack would probably be about the same effect. If things can stay chilly enough in places that have alot of snow, it will mitigate the issues some.

Overall.. quite concerned about the potential for a widespread moderate to perhaps major flooding with this upcoming storm. With that said, still a few days to get this storm figured out and get a better picture of where the heaviest QPF falls, temps, any shenanigans with frozen prior front and/or backend,track, strength etc. I wouldn't freak out, but if there are any really flood prone folks in here it's probably a good idea to prepare to deal with it.

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To further on Festus post, I actually put this on late sat night/sun morning when I threw on a disco about the now departing storm, but you can also go here, http://www.srh.noaa.....php?pil=FFHPA2

That is the headwater flood guidance printout for each of the flood categories in the headwaters that feed into the Susquhanna and Delaware Rivers. I'll use a local river as an example.

The numbers from left to right are how much rain would need to fall in a 1hr, 3hr, 6hr, and 12hr period to start flooding in each of the categories (minor, moderate, major) based on the flood criteria of that particular station.

Here is another link which is flash flood guidance values, which goes by county.

http://www.srh.noaa.....php?pil=FFGPA2

This is the amount of rain that needs to fall to start small stream flooding.. i.e the flood advisories that get issued. And the values for each county once again go for rainfall need over 1hr, 3hr 6hr, and 12hr to start flooding.

Now to comment on the values that are in there today. These guidance values are obscenely low compared to what you would usually see in the summer and fall if its farily dry, and they probably won't improve too much in the next couple days before it rains again. A 3-4 inch rainstorm in the fashion the Euro has it today in the Susquehanna basin would likely be hands down a widespread major flooding event for most/all tributaries and probably the Susquehanna itself. Even more concerning is the new snowfall that has fallen in the upper Susquehanna valley and on up into BGM's region. Not sure if you guys checked the PNS for up there, but there are widespread reports of 20+ inches of snow that fell from last nights storm. I'm not ready to buy into that widespread of an area of such excessive rainfall.. but even an inch or two of rain coupled with enough warmth to release at least a significant portion of that snowpack would probably be about the same effect. If things can stay chilly enough in places that have alot of snow, it will mitigate the issues some.

Overall.. quite concerned about the potential for a widespread moderate to perhaps major flooding with this upcoming storm. With that said, still a few days to get this storm figured out and get a better picture of where the heaviest QPF falls, temps, any shenanigans with frozen prior front and/or backend,track, strength etc. I wouldn't freak out, but if there are any really flood prone folks in here it's probably a good idea to prepare to deal with it.

One factor again appears to be precip types especially for places further north. 18Z NAM is up to the same stuff it was up to with the last storm. Now has us starting with advisory snow.

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