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Very Disturbing PRELIM DISC from HPC


Stormsfury

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It is just hard to believe any forecast with temps that hot in North Carolina. It is historically rare for a reason. But then again, Denver just hit 105.

Rare yes. Impossible no. For what it is worth, taking a statistical cumulative distribution function of Asheville's summer maximum temperatures, the 90th percentile is 90*F, and the 99th percentile is 94*F. But, the all-time record is 99, and this is the kind of heat set-up that leads to records.

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i agree. No way the foothills or mountains approach the upper 90's with soil moisture so high around here.

I remember last year the first heat wave was eaten up for the first 3 days here, because the entire county was super saturated early June from getting hit with a series of storms. Everyone around me went to 100, but I never did, and I don't think any part of the county did last year. So moisture in the ground means a lot, but this one could linger a while, like a week or so. I haven't had time to do much forecasting on it yet, since I spent so much time with Debby and Florida's floods.

One of my rules of thumbs on heat waves is the thickness level, 850 temps and location of the 594 ridge and surface winds. Of course lots of other things to account for like moisture, high clouds from cirrus debris. Anyway this one has all of it, excep the 594 ridge is not very pronounced on most models. But the 582 thickness field is widespread, and the +24 temps at 850 are expansive, and both centered directly under and east of the 588 to 594 dm ridge...throw in some downsloping westerly winds and Debby's remnants offshore and you have the ingredients for a potential super-heat wave for atleast a day. Everyone gets this basically in the Southeast. Tenn. Valley because that area is directly under the core of the ridge, and the Apps and piedmont because of added downsloping (despite some very wet grounds in some counties in NC--which will eat away the first day or 2 of the heat wave)

So, overall I think this can surpass Aug 2006 and 2007 in most areas, but I still think ECMWF is overdone overall. It did drop the big +30 now its +27 or so. A blend of it and more likely GFS at 850 of +24 to +26 looks reasonable. The big unknown is debris, which could save a few folks on the northern side especially in Kentucky and VA, but I'm not forecasting that yet. I do doubt 110 at the surface just around southeast Meck county and near Augusta though, but the idea is that that area maximizes downsloping, west to nw winds and a perfectly sunny day with high heat through the atmosphere.

For the Tenn. Valley, ECMWF paints a week long heat wave over 100 degrees , sometimes near 105 in Nashville, Tupelo, Huntsville, Memphis and Little Rock...so that area remains in the heart of the heat dome for a week, which is terrible news. West Kentucky is ina terrible drought, and this will eat away at all the crops in a hurry.

GFS surface winds Friday

post-38-0-14329000-1340745513_thumb.gif

ECMWF high temps Fri.

post-38-0-03055800-1340745542_thumb.jpg

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What soil moisture? We are WAY below normal in rainfall for the month! My grass is brown and the ground is rock hard. Any "moisture" will quickly go away today and tomorrow with a dry airmass and nearly clear skies. I think 97 is readily achievable in Asheville on Friday. Yes, I have the balls to say it!

The mountains and foothills consist of more than asheville. The only time I can recall Hickory or any other mountain/foothills location approaching or meeting 100 was in 2007 during the worst drought in the last 50 years under perfect conditions for a heatwave. I'm sure Charlotte/Greensboro/Raleigh will challenge or make 100 though. I suppose it's possible Hickory could, but based on climo i seriously doubt it.

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Been following this as well. ECMWF looked extremely warm at 850, with widespread +30, which looks overdone to me. The GFS though did have +27 over southern VA and northern NC Friday afternoon and the ridge placed just west, so that would equate to surface west winds mostly, which would only bring on more heat through downsloping, especially the Piedmont region.

There's a lot that could swing this either way. Ground moisture is one, and how much rain falls this week. I know its extremely dry in west Kentucky under where the core of the 594 heights will be on Thursday and Friday. Also, how much cirrus debris can drop southward from any MCC or frontal system in the Midwest...I know every year I see a cirrus canopy drop south to the Carolinas, which ends up messing up what would have been a truly miserable day, but it's hard to see that happening yet. But GFS does hint at a small cluster of storms in the Apps on Saturday (which would be slow movers , even assuming they break the extreme cap) And again on Saturday and Sunday evenings it generates some storms in north Alabama and the Tenn. Valley, so any debris from that would help some areas to stay under the absolute hot maxes forecasted.

One thing odd about this heat wave is the lack of a true round 594 height field. It's small and it ebbs and flows from Thursday, onward. Usually big heat waves have a very pronounced one. Also, the ECMWF is pushing that +30 temp very far east, I'm not sure I can recall ever seeing it even forecast that high a number this far east (its pretty common in western Plains heat waves though). Either way, going to get very hot, the only question is how hot. There's a lot of other factors that could hurt or help the temps achieve max status too, like where Debby's remains are and how strong it is. GFS lolligags it offshore Jacksonville, and if its in any kind of decent shape, that would be very bad news east of the Appalachians, through extreme subsidence and downsloping. It would be bad enough even without that there, but if things line up perfectly , widespread 100's are coming and some areas could surpass 105, maybe even touch 110, but I think a pretty wet ground may eat up some of the heat in part of the Carolinas, with recent convection.

Here's some stuff I put on my site earlier.

All time June Max temps through 2005:

post-38-0-46287000-1340646223_thumb.jpg

ECMWF surface temps Friday Forecast (120 hour issued 00z Mon)

post-38-0-58844800-1340646331_thumb.jpg

The euro has a 108* high here on Friday. If it hits 108 I'll eat my shorts lol. :lmao:

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The mountains and foothills consist of more than asheville. The only time I can recall Hickory or any other mountain/foothills location approaching or meeting 100 was in 2007 during the worst drought in the last 50 years under perfect conditions for a heatwave. I'm sure Charlotte/Greensboro/Raleigh will challenge or make 100 though. I suppose it's possible Hickory could, but based on climo i seriously doubt it.

2007, I think I had maybe 1 or 2 days that month over 100, we had a ton of 97-99's...oddly enough considering how miserable it was the whole month of August that year, 2 days wasn't much compared to those areas as close as 20-30 miles away.

The heat wave I remember as being extreme was in the early to mid 1990's (for some reason I'm thinking 1994)...I remember the local paper running a story with a listing of high's during that span, it was 6 consecutive days of 100+ degrees that was recorded by our NWS Coop Observer. The highest of the six days was like 104 with the rest of them being like 100, 101, 102...Robert, maybe you would know the exact date on that.

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If anything, The Southeast's 3 hottest days will likely be from Saturday through Monday with a bit of a temperment down on Tuesday. Friday's the "warmup" so to speak. I believe Saturday KCAE will challenge the 107 degree all time reading while the potential exists for heat index values to exceed 115, likely some spots in South Carolina will exceed 120. It's very hard to believe KATL's June record monthly high is 101. HPC's going 103 on Fri, followed by 105 on Sat for KATL. KAVL 98 on Sat. Irregardless, there will likely be a very large and expansive issuance of excessive heat warnings focusing starting Fri through the region and continuing til Tuesday in which Wednesday looks to bring a bit of a moderation of the excessive temperatures as the flow flattens to more zonal.

HPC Sat 6/30/2012 Max Temp Forecast.

post-1324-0-66357800-1340754126_thumb.gi

Max Heat Index values Sat 6/30/2012

post-1324-0-73186700-1340754183_thumb.gi

Max Heat Index Values Sun 7/1/2012

post-1324-0-85880700-1340754194_thumb.gi

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Just a perfect time for the AC unit to go bust! :axe:

The earliest it can be replaced is on Saturday. Thankfully, I've got a couple of LG mini-slicks in our finished basement that are working quite well and very energy-efficient. Looks like it'll be time to take the kids camping in the basement on Friday night!

I'm planning on getting a GAM5 High Efficiency Air Handler made by American Standard installed in place of my 16-year-old Rheem system. Supposedly, I'll get a little greater than a 14 SEER rating with the new outdoor unit and indoor handler, for those of you up-to-date on your HVAC terminology. I'm having to learn all this stuff on the fly.

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For 0Z on 6/30 at KATL at 850, the last three runs (at least) of the Euro (6/25 12Z and both 6/26 runs) have been forecasting an incredibly hot +29 C while all four of today's (6/26) GFS runs have forecasted ~+26 C! The FFC is being a bit conservative with high 90's as there's little doubt in my mind that KATL will exceed 100 F at least once during the Fri-Tue period. However, folks should be wary of the warm bias of the Euro and to a lesser extent the recent GFS. It is virtually a guarantee that 850's will not reach near the ridiculous Euro levels. That is the hottest 850 I've ever seen it or any model forecast for KATL. The hottest it forecasted during 8/07 was +26.5C. That day verified at "only" ~+23.5 C. The hottest actual 850's (at either 0Z or 12Z) I've been able to find for KATL since 1950 are only +24 C. OTOH, I do feel that there will be a shot at a record high 850 of ~+25 C.

Some KATL tidbits that may come in handy:

1) Hottest 850's at 0Z or 12Z at KATL since 1950: +24 C on 7/12 and 7/13 of 1980 (when the sfc temp. highs were 103 and 105 F, respectively) as well as 8/9 and 8/10 of 2007, when the sfc temp. highs were both 103 F.

2) Aug 07 KATL 850 model forecasts:

a. For the 8/9-11/07 period:

8/4 runs of Euro, GFS, and GGEM (i.e., 5-7 day forecast) were all at +25 C for their hottest. The actual hottest 850 was +24 C...so only 1 C too hot for all three models.

b. For the 8/14-17/07 period:

8/12 runs (2-5 day forecast): Euro as hot as +26.5 C and GFS as hot as +25.5 C. The actual hottest 850 was +23 C...so hottest Euro was 3.5 C too hot and hottest GFS was 2.5 C too hot.

c. For the 8/22-23/07 period:

8/20 runs (2-3 day forecast): Euro as hot as +25 C and GFS as hot as +23.5 C. The actual hottest 850 was +23.5 C...so hottest Euro was 1.5 C too hot and hottest GFS was perfect.

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The euro has a 108* high here on Friday. If it hits 108 I'll eat my shorts lol. :lmao:

Ok DT, don't think you'll have to do that. I think ECMWF is being too warm aloft, as it's had a tendency to over do ridges...which is part of the reason it messed up Debby's track. Still, at some point, its hard to see Hickory not hitting 100 or even possibly 101.

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Locations in Kansas have been either breaking or tying (or just missing) records set in 1911 on these past three or four dates. In that year, I am aware that the Great Lakes and northeast U.S. got into a super-heat-wave that ranks perhaps second to 1936 from about June 30th to July 4th. Record highs well into the 105-110 F range were observed and later broken in 1936. So, while I agree that the southeast is likely to see extreme heat soon, this could spread quite far north and involve most of the eastern third of the U.S. if the 1911 analogue remains valid. Model runs appear to be bringing the core of the heat into NC and VA but I suspect they may evolve to a wider spread of extreme heat into the northeast as well.

Also troubling, the heat has recently spread into Nebraska and South Dakota with values of 110-115 F resembling early stages of the epic 1936 heat wave and at a slightly earlier date. In early July of 1936 as many will know, the heat built up to 115-122 F in the plains states and then swept east to engulf the eastern third of the U.S. and southern Ontario. Many hundreds of people died in Toronto as well as large American cities where in all cases overnight lows failed to drop below 80 F.

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2007, I think I had maybe 1 or 2 days that month over 100, we had a ton of 97-99's...oddly enough considering how miserable it was the whole month of August that year, 2 days wasn't much compared to those areas as close as 20-30 miles away.

The heat wave I remember as being extreme was in the early to mid 1990's (for some reason I'm thinking 1994)...I remember the local paper running a story with a listing of high's during that span, it was 6 consecutive days of 100+ degrees that was recorded by our NWS Coop Observer. The highest of the six days was like 104 with the rest of them being like 100, 101, 102...Robert, maybe you would know the exact date on that.

I may be wrong but I'm thinking that big heat wave you spoke of happened in July of 1993. We hit 100 or higher early in that month and hit 97-98 for the rest of July into August. And from June into early Sept I only measured .40 of rainfall. By far the driest summer I remember in my area. At least it was a dry heat in 1993 though with dewpoints in the upper 50's on most afternoons. It was also hot around here in 1995 but I'm not sure we had many 100 degree days with that one. It felt worse than in 1993 though with dewpoints in the upper 70's much of the time with highs around 96-98 or so.

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Folks,

The 0Z GFS is sticking with its prior runs' bigtime/historic heat scenario with it stil having +26 C at 850 mb at KATL! That makes at least five GFS runs in a row showing that. The hottest 850 for KATL on record back to 1950 is +24 C.

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Folks,

The 0Z GFS is sticking with its prior runs'; bigtime/historic heat scenario with it stil having +26 C at 850 mb at KATL! That makes at least five GFS runs in a row showing that. The hottest 850 for KATL on record back to 1950 is +24 C.

I'm a stranger in this subforum :P but watching this heat wave closely as well. Just thought I'd point out that I didn't notice any glaring issues out west with the 850 mb thermal fields on the 00z analysis, which gives credence to the extreme stuff being spit out on the models. Of course there is some extra time before the big heat gets there so more time to potentially back off a little on future runs...

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I'm glad to have moved to another house with AC that works exceptionally well. Would've probably fell out in the other without the working AC with this upcoming heatwave as it was between 86-91 in the house during the day and 78-85 during the night and the highs were only in the upper 80s to lower 90s outside. Now it stays between 69-70 with the AC on and 71-76 with it off. Ready for some extreme temps but those look to be farther north as it will only reach 99 here Friday from the NWS.

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Once again FFC has a horrible forecast. They go no higher than upper 90s the entire period for ATL. My current forecast has at least 3 days over 100 here, 103 on Saturday but this may well be too conservative. If the Euro 850mb forecast is correct, oh my. 106-107 not out of the question.

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I'm glad to have moved to another house with AC that works exceptionally well. Would've probably fell out in the other without the working AC with this upcoming heatwave as it was between 86-91 in the house during the day and 78-85 during the night and the highs were only in the upper 80s to lower 90s outside. Now it stays between 69-70 with the AC on and 71-76 with it off. Ready for some extreme temps but those look to be farther north as it will only reach 99 here Friday from the NWS.

I'm glad we have a pretty good air conditioning in our home, it's gonna be working overtime during this heatwave. We'll probably have to leave it on for a few hours overnight, we usually turn it off at night and leave the ceiling fans on.

Once again FFC has a horrible forecast. They go no higher than upper 90s the entire period for ATL. My current forecast has at least 3 days over 100 here, 103 on Saturday but this may well be too conservative. If the Euro 850mb forecast is correct, oh my. 106-107 not out of the question.

They're treating this as if were waiting on a snowstorm to develop which really bothers me, they should be hyping this up more than they are doing considering how dangerous and deadly heat like this can be. At least now they have been going in the right direction, but they won't be fully in the right direction until they start putting some 100s in their forecast.

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I'll be honest and say I have been conservative in my forecast high the past few days. I've was forecasting 98-99 for this weekend on Monday and told my viewers don't be surprised to see the 100° on any of those days. I finally put the triple digit heat in the forecast yesterday for Friday and Saturday (100 & 101 respectively). Yes, 850 temps are crazy warm in the models but the real question is what will actually happen. A few outlets have 108 for Columbus on Saturday, which beats the ALL-TIME record high by 4°! That, in my opinion, is ridiculous and crazy. I will be the first one on here saying I honestly didn't think it would get that warm and move on.

We've been running heat preparedness stories the past two days in anticipation for this heat wave. I'm not in the business to hype things up, only tell them what I know and think. That's why I've been saying low 100s are a possibility since Monday. It lets people know warm temperatures are on the way and to start preparing or thinking about it now. The average Joe Smith couldn't care less if it hits 101 or 104 or 105. It's just HOTTER than hell to them.

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I'll be honest and say I have been conservative in my forecast high the past few days. I've was forecasting 98-99 for this weekend on Monday and told my viewers don't be surprised to see the 100° on any of those days. I finally put the triple digit heat in the forecast yesterday for Friday and Saturday (100 & 101 respectively). Yes, 850 temps are crazy warm in the models but the real question is what will actually happen. A few outlets have 108 for Columbus on Saturday, which beats the ALL-TIME record high by 4°! That, in my opinion, is ridiculous and crazy. I will be the first one on here saying I honestly didn't think it would get that warm and move on.

We've been running heat preparedness stories the past two days in anticipation for this heat wave. I'm not in the business to hype things up, only tell them what I know and think. That's why I've been saying low 100s are a possibility since Monday. It lets people know warm temperatures are on the way and to start preparing or thinking about it now. The average Joe Smith couldn't care less if it hits 101 or 104 or 105. It's just HOTTER than hell to them.

Even if they do verify, I think the bigger question is what is the mixing depth during the peak heating hours? On August 21, 1983, the day that Asheville hit 100*, the mixing depth on the GSO sounding was nearly to 550mb. Even at 12Z, it was up to 700mb. If the depth of the true mid-level thicknesses can be tapped, I think widespread low 100s in the piedmont and midlands of NC/SC are likely.

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Folks,

The 0Z GFS is sticking with its prior runs' bigtime/historic heat scenario with it stil having +26 C at 850 mb at KATL! That makes at least five GFS runs in a row showing that. The hottest 850 for KATL on record back to 1950 is +24 C.

Yep, it's the consistency of the model runs that gives me confidence in my upper 90s forecast for the mountains and easy low 100s for the Piedmont/Foothills areas. IMO, KATL tops 100 with no problem.

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Reading this thread is depressing. :axe:

But if we are going to be hot, we might as hell have record heat. Several years back it hit 100-102 or so about this time IIRC so if we get that hot it won't be unprecedented here but if we get to 105 to god forbid 110, that will be damn impressive.

Impressive, or depressing, or sickening indeed is BHM is forecasting highs at or above 100 in Tuscaloosa for the next 7 days :axe: (although their pin point forecast "only shows upper 90s today and around day 5 but their graphic shows 100 today)

Given the possible historic heat, will go ahead and pin this thread.

Ironic to say the least that we have this terrible heat coming when this morning it was or close to record lows here with a low of 57.

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