Medium-long range thread

[Grothar]

The medium range forecast looks fantastic for the Philly metro... at least until Rina spoils the party next weekend. The MJO giveth and the MJO taketh away.

Time to start a new thread on Rina- models looking like another Irene coming our way next week

[SmokeEater]

Time to start a new thread on Rina- models looking like another Irene coming our way next week

It isn't even an area of invest yet.

[Rainshadow]

Ugh, leaves are really ugly here around the Lake Cayuga area. 70% still green with large leaf droppings. It appears the area was affected by some sort of leaf fungus causing the leaves to get brown spots and quickly fall off the trees.

Sorry to hear about that.

[phlwx]

It isn't even an area of invest yet.

One would think he'd want to enjoy a week of dry weather first...

[am19psu]

So much can go wrong with bringing what looks to be Rina up the coast. It's cute the models all agree that the Plains s/w will dig far enough south to grab Rina and bring it up the coast, but I'm not sold on that yet. That's a helluva ridge over Canada to displace to get the s/w far enough south to entrain Rina.

[am19psu]

So much can go wrong with bringing what looks to be Rina up the coast. It's cute the models all agree that the Plains s/w will dig far enough south to grab Rina and bring it up the coast, but I'm not sold on that yet. That's a helluva ridge over Canada to displace to get the s/w far enough south to entrain Rina.

Almost on cue, the models diverged wildly today. The good news is, after the tropical stuff, the following week looks like a carbon copy of this week coming up.

[NaoPos]

Almost on cue, the models diverged wildly today. The good news is, after the tropical stuff, the following week looks like a carbon copy of this week coming up.

You'd have to think that if the models are varying on that set up, you'd have to take the following week with a grain of salt

[am19psu]

You'd have to think that if the models are varying on that set up, you'd have to take the following week with a grain of salt

Nah. MJO ftw.

[NaoPos]

Assuming it propagates to phase 8?

[am19psu]

Assuming it propagates to phase 8?

Yeah, and then 1. We should be looking at decent weather through, like, the 23-28th. After that, a big cold shot is going to come in.

[Sunny and Warm]

Almost on cue, the models diverged wildly today. The good news is, after the tropical stuff, the following week looks like a carbon copy of this week coming up.

There was kind of a hint of something off the east coast of FL several days ago. It may be that the storm starts in the gulf and then reforms east off FL and/or GA. In either case, it seems the high to the north blocks or slows QPF progression up the coast to a degree. The gradient to the north is tight in the attached forecast. Do you see it that way as well? What is the max you see from this? Mainly Jersey or is PA in the game? Thanks

[am19psu]

There was kind of a hint of something off the east coast of FL several days ago. It may be that the storm starts in the gulf and then reforms east off FL and/or GA. In either case, it seems the high to the north blocks or slows QPF progression up the coast to a degree. The gradient to the north is tight in the attached forecast. Do you see it that way as well? What is the max you see from this? Mainly Jersey or is PA in the game? Thanks

I honestly have no idea at this point. It really depends on whether the remnants of whatever forms down there phase with the s/w moving out of the Plains and the models are having a devil of a time resolving the amplitude of that feature. Worst case could be a widespread 4-6", best case is a light shower as it passes by 200 mi offshore.

[Sunny and Warm]

I honestly have no idea at this point. It really depends on whether the remnants of whatever forms down there phase with the s/w moving out of the Plains and the models are having a devil of a time resolving the amplitude of that feature. Worst case could be a widespread 4-6", best case is a light shower as it passes by 200 mi offshore.

I can take 4-6" down south, but not at the PA house. The water table is still extremely high in Lehigh County. I'd like 2-3 weeks of dry weather at this point.

[phlwx]

I honestly have no idea at this point. It really depends on whether the remnants of whatever forms down there phase with the s/w moving out of the Plains and the models are having a devil of a time resolving the amplitude of that feature. Worst case could be a widespread 4-6", best case is a light shower as it passes by 200 mi offshore.

Anything but worst case would be fine with me...thanks.

[Quakertown needs snow]

I honestly have no idea at this point. It really depends on whether the remnants of whatever forms down there phase with the s/w moving out of the Plains and the models are having a devil of a time resolving the amplitude of that feature. Worst case could be a widespread 4-6", best case is a light shower as it passes by 200 mi offshore.

please not 4-6".

yard would freeze saturated for the winter followed by a soggy spring.

[am19psu]

The good news: models have trended weaker with the surface low. The bad news: they seem to bring the low up the coast with a def band setting up over E PA. If I had to put something out right now, I'd go with 1-3" for the metro.

On the bright side, it still looks warm and dry for about 5-7 days after the coastal low.

[Sunny and Warm]

The good news: models have trended weaker with the surface low. The bad news: they seem to bring the low up the coast with a def band setting up over E PA. If I had to put something out right now, I'd go with 1-3" for the metro.

On the bright side, it still looks warm and dry for about 5-7 days after the coastal low.

well, that's mostly bad news, as 1-3" is almost as bad as 4-6" with issues those amounts will cause.

[SmokeEater]

HPC starting to bite, but does it sound like another Irene as of yet? Not even close.

MAIN WEATHER EVENT OVER CONUS THIS PERIOD WILL BE THE AREA OF LOW

PRESURE DEVELOPING IN THE NERN GLFMEX AND REFORMING OFF THE SOUTH

ATLC SEABOARD. THIS SYSTEM WILL MOVE NORTHEASTWARD TO THE NC COAST

DAY 5 THURS AND TO NEW ENGLAND WATERS DAY 6 FRI. MDT TO HEAVY

RAINS CAN BE EXPECTED ALONG AND WEST OF ITS TRACK FROM THE

SOUTHEAST COAST INLAND TO THE APPLCHNS ALONG ITS ENTIRE PATH AS IT

MOVE NORTH INTO THE NEW ENGLAND AREA. WIDEPREAD AMOUNST OF 1-3

INCHES CAN BE EXPECTED FROM NORTHEAST FL AND GA NORTH INTO NEW

ENGLAND.

RAUSCH/ROSENSTEIN

[Sunny and Warm]

current HPC thinking. Not too bad.

[dssbss]

What's the outlook for the precip in the south to move up this direction? Are we looking at another Lee training situation or just some steady rain? Some of the tweets from Accuwx are talking about flooding?

[NaoPos]

[SmokeEater]

What's the outlook for the precip in the south to move up this direction? Are we looking at another Lee training situation or just some steady rain? Some of the tweets from Accuwx are talking about flooding?

You answered your own question there. Looks like a 1-3 event regionwide. Not the end of the world.

[Grothar]

What's the outlook for the precip in the south to move up this direction? Are we looking at another Lee training situation or just some steady rain? Some of the tweets from Accuwx are talking about flooding?

With one to three inches, of course there will be small stream flooding. The water table is still high based on the observed high base flows in the streams. Four to six inches will cause serious flooding as with Lee remnants. I am becoming more concerned that the water table will remain high going into winter and will create a real serious flooding situation if the ground freezes all the way to three feet and the snow pack is becomes higher than 24 inches ( January 1996 redux) and we have rain on top of the snow pack.

[NaoPos]

With one to three inches, of course there will be small stream flooding. The water table is still high based on the observed high base flows in the streams. Four to six inches will cause serious flooding as with Lee remnants. I am becoming more concerned that the water table will remain high going into winter and will create a real serious flooding situation if the ground freezes all the way to three feet and the snow pack is becomes higher than 24 inches ( January 1996 redux) and we have rain on top of the snow pack.

1st Jan 96' analogue of the winter! Congrats!

[SmokeEater]

1st Jan 96' analogue of the winter! Congrats!

Not even into mid October yet, and it has been called. But I'd expect nothing less from Grothar. There's too many things wrong to count with his post, I think I'll just leave it alone for now.

[JamieOber]

With one to three inches, of course there will be small stream flooding. The water table is still high based on the observed high base flows in the streams. Four to six inches will cause serious flooding as with Lee remnants. I am becoming more concerned that the water table will remain high going into winter and will create a real serious flooding situation if the ground freezes all the way to three feet and the snow pack is becomes higher than 24 inches ( January 1996 redux) and we have rain on top of the snow pack.

If you have two feet of snow the ground wouldn't freeze that deep, plus wet ground tends to not freeze as deep as dry ground.

[SmokeEater]

HPC showing a 2.3 inch maximum regionwide. More then doable.

[Grothar]

If you have two feet of snow the ground wouldn't freeze that deep, plus wet ground tends to not freeze as deep as dry ground.

Yes, the ground will freeze at two feet. The avg winter frost depth is up to 36 inches for SE PA. The IBC building code indicates this to be true. In most cases the ground will freeze before we get our first significant snowfall. If we have several days of below freezing temps in late November to early December, the depth of the snow pack on already frozen ground in December will mean little. I also do not understand how wet ground freezes any less than dry ground but in fact the soil porosity would indicate the opposite to be true. The water table usually remains static in December, so unless we get virtually no rain and having above temps in November, we stand a fair chance of seeing some flooding from a January thaw and a heavy rain on the snow pack. Actually I was wrong in using 1996 as an analog when realistically I do not know an analog for the scenario where we have a small snow pack on an extensive frost depth with a January thaw and heavy rain event..

[NaoPos]

Yes, the ground will freeze at two feet. The avg winter frost depth is up to 36 inches for SE PA. The IBC building code indicates this to be true. In most cases the ground will freeze before we get our first significant snowfall. If we have several days of below freezing temps in late November to early December, the depth of the snow pack on already frozen ground in December will mean little. I also do not understand how wet ground freezes any less than dry ground but in fact the soil porosity would indicate the opposite to be true. The water table usually remains static in December, so unless we get virtually no rain and having above temps in November, we stand a fair chance of seeing some flooding from a January thaw and a heavy rain on the snow pack. Actually I was wrong in using 1996 as an analog when realistically I do not know an analog for the scenario where we have a small snow pack on an extensive frost depth with a January thaw and heavy rain event..

That's a lot of what if's. Lot of variables there. You're painting a "perfect" conditions set up. You have to think warm winter , minimal qpf, cold dry spring. Any of these variables, separate from each other and non dependent, would damper the worst case scenario you're painting.

Bottom line, let's worry about it in march.

[Sunny and Warm]

Yes, the ground will freeze at two feet. The avg winter frost depth is up to 36 inches for SE PA. The IBC building code indicates this to be true. In most cases the ground will freeze before we get our first significant snowfall. If we have several days of below freezing temps in late November to early December, the depth of the snow pack on already frozen ground in December will mean little. I also do not understand how wet ground freezes any less than dry ground but in fact the soil porosity would indicate the opposite to be true. The water table usually remains static in December, so unless we get virtually no rain and having above temps in November, we stand a fair chance of seeing some flooding from a January thaw and a heavy rain on the snow pack. Actually I was wrong in using 1996 as an analog when realistically I do not know an analog for the scenario where we have a small snow pack on an extensive frost depth with a January thaw and heavy rain event..

The bolded sentence is incorrect. Code is based on maximum expected depth, and is not an average. The Lehigh Valley where you are rarely sees the freeze line greater than 12". The largest freeze depth I've ever seen was 1976-77, which was a very cold and dry winter, and those depths where you are were not at 36". In fact, many areas were under a drought watch that winter. Bottom line is that you only need a few inches of frozen ground to get a 1996 redux.