Stormy, Very Wet, Active Pattern Second Half of April

[FoothillsNC]

The GFS is usually good on longer term NAO and big changes, and for several runs it, and the other models have hinted at a developing west based -NAO and in conjunction with an Aleutian Low that will shoot impulses down the Rockies and into the southern Plains to East Coast. I 'm not sure where the most intense storminess will be yet, but with a building NAO it could be shunted a little more south and east than models show, but verbatim its around the lower Ohio and Tenn Valleys and westward to Ok/Mo/KS region. I think the odds are very high that west of the Appalachians will deal with a very active severe weather period and eventual Flood threat, since cumulative rains are probably going to exceed 10" in the last half of April, in a large region if this comes to pass. Its possible that the entire Southeast gets in on this, we should know more in a few days, but for now I'd say from the Apps, and westbound are ground zero on almost non-stop action starting with the Friday system, then a few days break, then a series of s/w taking the southern track which might roughly repeat every couple of days. Right now this still favors mainly a "west of Apps" big deal but the door is open for more expansion, if the -NAO materializes. The models a lot of times don't handle the resultant storm tracks properly until later on.

[buckeyefan1]

Considering I have doubled my rainfall amount in April from last year, any leftovers we get east of the mts will be a bonus I hope this trend continues into the summer months as I sure do miss the chance of those daily thunderboomers that would bring some much needed relief from the hot, sultry weather

[Jebman]

If this results in a wet pattern for the Mid Atlantic for the 2nd half of April - You're gonna need a bigger lawnmower. Lawns are really starting to grow here in N VA and we have already had a lot of rain.

[LithiaWx]

That looks like a snowy almost perfect setup if we were in the winter months! Too bad we could not have had this pattern materialize in the winter months.

[Carvers Gap]

The GFS is usually good on longer term NAO and big changes, and for several runs it, and the other models have hinted at a developing west based -NAO and in conjunction with an Aleutian Low that will shoot impulses down the Rockies and into the southern Plains to East Coast. I 'm not sure where the most intense storminess will be yet, but with a building NAO it could be shunted a little more south and east than models show, but verbatim its around the lower Ohio and Tenn Valleys and westward to Ok/Mo/KS region. I think the odds are very high that west of the Appalachians will deal with a very active severe weather period and eventual Flood threat, since cumulative rains are probably going to exceed 10" in the last half of April, in a large region if this comes to pass. Its possible that the entire Southeast gets in on this, we should know more in a few days, but for now I'd say from the Apps, and westbound are ground zero on almost non-stop action starting with the Friday system, then a few days break, then a series of s/w taking the southern track which might roughly repeat every couple of days. Right now this still favors mainly a "west of Apps" big deal but the door is open for more expansion, if the -NAO materializes. The models a lot of times don't handle the resultant storm tracks properly until later on.

Foothills, does this also imply that a cooler pattern will develop? I wasn't sure if a -NAO in spring would mean the same things as winter in terms of temps. Also, do you think summer will turn out to be hot and dry like last summer as the atmosphere might continue to respond to a La Nina pattern - like "memory" on fishing line? I did read that the Pacific is to return to ENSO-neutral conditions by June ( http://www.cpc.ncep....s-fcsts-web.pdf ). Or do you think the atmosphere is already responding to the neutral signal?

[FoothillsNC]

Foothills, does this also imply that a cooler pattern will develop? I wasn't sure if a -NAO in spring would mean the same things as winter in terms of temps. Also, do you think summer will turn out to be hot and dry like last summer as the atmosphere might continue to respond to a La Nina pattern - like "memory" on fishing line? I did read that the Pacific is to return to ENSO-neutral conditions by June ( http://www.cpc.ncep....s-fcsts-web.pdf ). Or do you think the atmosphere is already responding to the neutral signal?

to be honest I haven't even looked at the Enso signals lately, I need to do that, but I'm pressed for time lately. I also haven't thought much about the Summer. I will say usually the Southeast has gone into a ridge aloft in April or May , which usually lasts the whole Summer but something tells me that won't be the case this time, I guess time will tell. So far it looks active but of course that can be shut off almost instantly at any time, as we've seen many times in the past. Last Summer was a sight to behold with its strong ridging and intense heat waves, I hope we've seen the last of that for a few years, but I don't know. If I get time , I'll look more at forecasting the Summer in general, I know Winter forecasts are popular but not so much Summer.

As for temps, with the NAO yes if its neg. even this time of year we'd be cooler than normal, but at first I actually think the Southeast quadrant will get HOT. A front will stall next week west of the Apps, placing most all the Southeast in the warm sector, but as I alluded to, the models beyond that I don't trust, but I do somewhat think the GFS forecast of pushing the front and storm track further south will come to fruition, or atleast the chance of that, no guarantees...and its then we'd get cooler and wetter, which really would probably be a great showery, and "thunderstormy" period, and maybe some damming days east of the Apps, its too far out, but if the 50/50 low happens, then usually that happens. Thats late next week and beyond though.

[Gastonwxman]

Interesting write up Robert. I'm beginning to think myself of that very same idea about sustaining a period of where increased precipitation and storminess hangs around for the Southeast instead of the usual warm and dry conditions that are experienced. You've got a parade of storm systems that takes the perfect track to bring much needed rainfall for a few folks that have been missing out, each having a unique effect be it the severity of individual (or linear) thunderstorms that erupt or substantial precipitation accumulation of rainfall in the event of persistent heavy rain. The ridge doesn't look to be as pronounced as originally thought and should keep a good chunk of us in somewhat cooler than normal temperatures (just my thinking on that assuming the -NAO takes over for a while). Just depends on whether or not we get the setup to happen but odds are it will and guidance will probably keep the idea of it for some time despite a few recent misses they made regarding the severe weather(minor errors at best though). In a situation as this you can't help but think of how things will play out but luckily seeing a setup like this on the modeling should translate for us to stay active for a few weeks. I like the potential of everyone getting on this kind of pattern, which will mean even places east of the Appalachians would have to watch out if it's to come to fruition. If anyone's noticed, we seem to have something on our hands 2-3 days after an event has occurred (think last week on Mon. night-early Tues and then Fri-Sat.) The same thing repeats itself once more for this week; a system during the early part and then something else during the weekend. We shall see but the at least the idea is legit.

[FoothillsNC]

this idea probably won't come to pass as I first thought it might. There will be a stalled front with some showers and storms mid week across the Tn Valley and Mid Atlantic, maybe into GA, but then it lifts north, probably for a while, leaving the Southeast mostly under a heat ridge and mostly dry. However a couple more fronts are still slated to come through in the next 2 weeks, but a lot of the time we'll be dry and warm and increasingly humid with the Bermuda ridge...eventually pop up storms will become more common. The real repeating rains will be closer to the Ohio Valley, Lakes Midwest and down to Ok/KS.

[Snowless in Carrollton]

Isn't it a little early for pop up storms ? Usually we don't see those until about Mid May. Average high this time of year is only about 73 here.

[FoothillsNC]

Isn't it a little early for pop up storms ? Usually we don't see those until about Mid May. Average high this time of year is only about 73 here.

It is a few weeks early. But the ECM and GFS have a bermuda ridge showing up with rich gulf moisture, abundant high dewpoints and probably just warm enough temps to reach convective level, atleast some areas of the Southeast. Normally the mtns are a good spot at first, but the GFS has afew in Ms and AL well ahead of the front, so I'd call those a hybrid maybe of popup and front driven. Either way, we're going to get warm and into a much higher dewpoint pattern pattern soon....just a matter of time before the pop-ups begin. I like how the pattern is looking for the next couple of weeks, still pretty active and atleast no closed ridges over the Southeast, instead we get a Bermuda offshore which will keep pumping Gulf moisture inland.

[FoothillsNC]

Its still a ways out but around days 7 through 9 or 10 the models have a huge Bermuda ridge, and some blocking well north in the NW Atlantic and that might be a good combo to pump in moisture ahead of a slow moving deep trough that will be coming through the Plains. Matter of fact the Bermuda ridge is perfectly placed on the models, and I'd be surprised if theres not a flood threat eventually, but we have to see how quickly the western trough evolves or moves east. Still favors west of the Apps at first, with major Spring rains over the Corn Belt of Illinois, Ky, Ind Ark and Mo.

[FoothillsNC]

Major rain event showing up on NAM and GFS for Indiana southwest to northern ARK over the next few days. Some areas are just going to get trained on, with up to 10" probably more. This will be a big flooding event, even for the area that's used to big Spring rains. And this is before the next system really gets organized...even more will come when that tracks over the area.

[DaculaWeather]

And boy have they, here's a storm total image from my GRL3 radar from Paducah. I have this radar http://www.daculaweather.com/grlevel3/storm_mode_2.php and Little Rock up right now

http://www.daculaweather.com/grlevel3/storm_mode_1.php

[DaculaWeather]

In just a little while I'll have enough images for Oklahoma City http://www.daculaweather.com/grlevel3/storm_mode_3.php radar. It won't display any images until they are all there.

[DaculaWeather]

Coming up today:

...ARKLATEX REGION INTO THE MID MS VALLEY AREA...COMPLEX -- BUT POTENTIALLY SIGNIFICANT -- SCENARIO APPEARS TO BE UNFOLDING ACROSS THIS REGION...AS PERSISTENT WARM ADVECTION INV OF A SURFACE WARM FRONT RESULTS IN A SLOW INCREASE IN STORM COVERAGE AHEAD OF A RAPIDLY-APPROACHING UPPER FEATURE DIGGING SEWD FROM THE ROCKIES INTO THE SRN PLAINS. WHILE SEVERE POTENTIAL IS APPARENT ACROSS PORTIONS OF THE AREA -- PARTICULARLY INV OF THE WARM FRONT --THROUGH MUCH OF THE PERIOD...THREAT SHOULD RAMP UP RAPIDLY FROM W TO E BY LATE AFTERNOON ACROSS SERN OK/E TX...AND THEN INTO THE EVENING ACROSS THE ARKLATEX INTO NRN LA/AR AND EVENTUALLY THE MID MS VALLEY REGION.FLOW ALOFT IS FORECAST TO INCREASE AS THE UPPER SYSTEM APPROACHES...AND AS BACKING/INCREASING LOW LEVEL FLOW EVOLVES IN RESPONSE...

SHEAR WILL BECOME HIGHLY-FAVORABLE FOR SUPERCELLS. IN ADDITION...IT APPEARS THAT LOW-LEVEL SHEAR WILL BECOME QUITE FAVORABLE FOR LOW-LEVEL ROTATION -- AND THUS THE POSSIBILITY OFSTRONG TORNADOES...ESPECIALLY OVERNIGHT FOCUSED ON AR AND VICINITY.

GIVEN THIS POTENTIAL...UPGRADE TO HIGHER CATEGORY RISK APPEARS LIKELY IN LATER FORECASTS.

[FoothillsNC]

What a month this has been. With all the severe outbreaks, hail, tornadoes, winds, and flooding rains. April 2011 is going to be a standout month for a long time I think. Some areas either side of the Miss. River and Ohio River areas are over 20" of rain and 15" is very common. Still there are dry pockets in central SC to central NC with only 2" of rain for the month, and even drier for central to eastern and southeast GA with barely an inch.

[buckeyefan1]

What a month this has been. With all the severe outbreaks, hail, tornadoes, winds, and flooding rains. April 2011 is going to be a standout month for a long time I think. Some areas either side of the Miss. River and Ohio River areas are over 20" of rain and 15" is very common. Still there are dry pockets in central SC to central NC with only 2" of rain for the month, and even drier for central to eastern and southeast GA with barely an inch.

It's nice to see my area colored in something other than blue or green.....I got lucky this month