Before I get into the details for the longer-range, I want to focus in on a potentially “major” heat surge beginning as early as Friday, through early next week. Ice and I have alluded to this possibility over the past several weeks, and it now appears it’ll likely come to fruition.

Prior to Friday, we’ll have a frontal boundary sagging southward from the Mid-western US, becoming nearly stationary for a time on Wednesday — in effect this will allow a series of waves of low pressure to propagate W-E along the baroclinic zone, sparking strong/severe T-storms in association with forcing. The first of such waves should impact the Lower lakes region / Ohio valley tomorrow, the second Tuesday night or Wednesday in the Northeast, and maybe a third wave in the southern mid atlantic on Thursday. The FROPA could yield as much as 24-36 hours of cooler/drier air (namely Thursday) before the searing heat surges northeastward into the Mid-atlantic by Friday, and the rest of the NE by the weekend.

Friday IMO is widespread low 90s across much of NJ, PA, ect — significantly cooler over central/eastern Long Island as the flow will be SWLY.

Then I believe widespread 90s are a good bet Saturday, Sunday, and Monday for most away from the immediate shoreline. And I’m not just talking low 90s — many of the normally warmer spots in NJ (i.e. parts of central/NE NJ) could make a run at 95F or even a bit higher. Not sure which day(s) that is — but the period from Friday to Monday is very hot and humid — real change from the past several weeks.

So all in all – a good number of stations may record more than the minimum requirement for a heat wave (3) while parts of Long Island may very well see no 90s.

500mb ridge on Friday afternoon per the GFS — heights skyrocketing > 588dm up and down the east coast. 850mb temperatures are near of above 20c throughout the Fri-Mon period, indicative of 5,000ft temps approaching 70F — translation to surface — low to mid 90s on average. There will be some 95F+ readings:

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_500_096s.gif

Further out into time — large scale teleconnection indices have/are reversing, thus I’m my confidence level in a warmer than normal June is fairly high at this point. Below are the PNA, NAO and AO forecasts per the GFS ensembles in that order:

Note a -PNA, +AO/NAO regime, which suggests the tendency for a Pac NW and SE Canada trough, with the mean heat ridge positioned in the Plains.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/pna.sprd2.gif

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

If anyone’s been following ENSO — here are the latest weeklies:

http://www.bom.gov.au/climate/enso/indices.shtml

Down to -0.28c in region 3.4, and above 0 in all other regions save for the further west one — region 4. What this means is easterly trade winds continue to weaken in conjunction with an overall warmer of subsurface SST’s. These warmer waters have been reaching the surface recently — thus we’re now in the “neutral range” for ENSO.

The next few months so see a neutral ENSO pattern prevail: -0.5c to +0.5c in region 3.4.

Implications for the summer are manifold — several of which were mentioned in the thread already, 1) Analogs to current pattern and weakening La Nina signal during the summer months argue for above normal precipitation — due to a combination of factors, namely frequent T-storms. 2) A temperature pattern which should average slightly above normal for the summer June-July-Aug months. I don’t think we’re talking a searing hot summer, or a cooler than normal summer. Slightly above average IMO with many shots of T-storms and cool shots from the NW. However the warm should outduel the cool overall.

My confidence is high on a solidly warmer than normal June, wetter than normal summer, active T-storm season, and a warmer than normal summer overall  but not blowtorch.

More support for a warmer than normal summer — the warm/positive state of the AMO. There’s a tendency for eastern summers to be warmer than normal when the atlantic profile is also warm.

This is one of the main reasons why I’ve discounted the coolish years of the 60s/70s as analogs for the upcoming summer, even though their ENSO regimes were similar.

Here’s the current SSTA profile:

http://weather.unisys.com/archive/sst/sst_anom-080608.gif

Note the similarities to June of 1999 — also a +AMO summer following a strong la nina winter.

http://weather.unisys.com/archive/sst/sst_anom-990606.gif

Now take a look at the overall temp departures for the summers featuring +AMO (warmer atlantic):

Generally anywhere form +0 to +2.

Also note virtually all years from prior to mid 50s or after mid 90s (the +AMO cycles).

I think we’ve got very good hard data in favor of the warmer than avg summer idea.

Verification – Summer 2008

This is always a depressing time of year, as Labor Day signals the end of the warm season, at least to me. But on the bright side the first day of meteorological winter is only 3 short months away! Hard to believe how fast time flies.

Here are the key aspects of my summer forecast and how it turned out:

— June forecast temps: +1 to +3
–June forecast precip: Above normal
–T-storm activity: Above average

–July forecast temps: around +1
–July forecast precip: Above normal
–T-storm activity: Above average

–August forecast temps: +1
–August forecast precip: Above normal
–T-storm activity: above normal

June-July-August total temp departures: 0 to +2 (slightly warmer than normal)
Precip 3 month: Above normal
T-storms: Above normal

Now here are some select cities in the NYC region for each month:

NYC:
June temps: +2.8
Precip: +0.86

Newark:
June temps: +3.4
Precip: +2.23

Islip:
June temps: +3.1
Precip: -0.5

NYC:
July temps: +1.9
Precip: -1.5

Newark:
July temps: +1.5
Precip: -1.5

Islip:
July temps: +1.3
Precip: +0.65

NYC:
August temps: -1.3
Precip: +1.36

Newark:
August temps: -1.4
Precip: -1.2

Islip:
August temps: -1.8
Precip: -1.2

NYC:
Total summer temp: +1
Precip: +0.44

Newark:
Total summer temp: +1.1
Precip: -0.7

Islip:
Total summer temp: +0.9
Precip: Below normal

IMBY — I ended up with a +1 temp departure and +0.6 for precip.

In terms of grades I think I was B+ for June temps/precip, very good with July A/A+ , and August not as good as temps were slightly below normal as was precip, probably around a C/C-.

So total I’d say about a B/B+ call for the summer overall. Had the slightly warmer than normal temp idea, very active T-storm season, and plentiful rainfall for most. Other comments/criticisms are appreciated. Pretty happy with it.