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May 2018 Discussions & Observations Thread

Rtd208

By Rtd208,
in New York City Metro

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Cfa

Cfa

Posted
Posted

Does the NAO have much of an affect on summer weather around here?

Our summers are far less variable than the other seasons (thankfully). But does that mean all teleconnections hold less weight? Or just certain ones?

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bluewave

bluewave

Posted
Posted
2 hours ago, Cfa said:

Does the NAO have much of an affect on summer weather around here?

Our summers are far less variable than the other seasons (thankfully). But does that mean all teleconnections hold less weight? Or just certain ones?

It all depends on how strong of a positive or negative NAO/AO we get during the summer. The interaction with the other teleconnections is also important. The record low -AO in June-July 2009 combined with the -EPO to produce near record cool weather.The record -NAO influence in July 2015 was muted by a more +EPO. So we finished with a warm departure.

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Brian5671

Brian5671

Posted
Posted
46 minutes ago, CIK62 said:

Temperature struggling here between 60-61 on a light southeast wind---a no-no signal for the beach with a target of just 70 in the City today.    Yesterday was perfect on beach.

been stuck in the high 60's here all day despite light winds and clear skies...

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psv88

psv88

Posted
Posted
1 hour ago, CIK62 said:

Temperature struggling here between 60-61 on a light southeast wind---a no-no signal for the beach with a target of just 70 in the City today.    Yesterday was perfect on beach.

 

16 minutes ago, Brian5671 said:

been stuck in the high 60's here all day despite light winds and clear skies...

72 out here on the island...

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psv88

psv88

Posted
Posted
56 minutes ago, bluewave said:

Hopefully, the weekend backdoor comes through Saturday night  and we get a dry but cool Mother's Day. Backdoors usually don't have much moisture. But it would be nice to avoid any light showers or drizzle for Sunday. Models may need a few more days for exact timing.

wouldn't mind some drizzle to clear out the pollen. im dying here

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Rtd208

Rtd208

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Interesting discussion from Mt.Holly. 

.LONG TERM /THURSDAY THROUGH TUESDAY/... 
  The long-term period looks active, with a setup that looks 
  favorable for an east-west axis of heavy rainfall that has at  
  least some potential to affect portions of the CWA Saturday  
  onward. 
   
  Positively-tilted trough is anticipated to move through the 
  Northeast/Mid-Atlantic on Thursday with a cold front sagging 
  southeastward from the lower Great Lakes and adjacent southeast 
  Canada upstream of a prefrontal trough crossing New 
  York/Pennsylvania during the day. Sufficient diabatic heating 
  will allow for some surface-based instability to develop and 
  focused lift via differential heating, topographic  
  effects, and boundary confluence/convergence should be  
  sufficient to develop scattered convection to our west by late  
  morning. Just how far east this convection makes it before  
  nocturnal cooling Thursday evening is the main forecast concern, 
  with the ECMWF/ICON keeping most precipitation west of the  
  Delaware River and the GFS more progressive, allowing scattered  
  convection to reach the coast. High-resolution/convection- 
  allowing models indicate at least some potential for storms  
  reaching the coast (e.g., the 00Z NAM Nest), but higher  
  potential is certainly northwest of the I-95 corridor. Did not  
  change inherited PoPs much, keeping chance-to-likely PoPs from  
  the urban corridor northwestward but at least slight-chance PoPs 
  all the way to the coast. 
   
  The environment is supportive of strong to severe storms, with  
  deep-layer bulk shear 35-45 knots and CAPEs approaching 1000  
  J/kg during peak heating...especially west of the Philly area  
  (one caveat to this discussed below). Forecast hodographs show  
  some curvature, and high-resolution models indicate potential  
  for a combination of discrete storms and line segments along  
  initiating boundaries. Would not be surprised to see some  
  rotating storms during the afternoon with potential for some  
  marginally severe hail in addition to strong downdraft gusts.  
  Again, one of the main question marks is how far east the  
  convection makes it before the window closes on the severe  
  potential. Will definitely need to keep an eye on this. 
   
  A potential complication to the above is residual morning  
  clouds (low stratus and/or fog), with the NAM showing its usual  
  soup hanging on in much of the area for a few hours after  
  sunrise. This may have implications on how much instability can  
  develop, should this materialize overnight. 
   
  Convection should dissipate fairly rapidly after dark Thursday 
  evening, with the lagging cold front set to move through 
  overnight into Friday morning. Skies are expected to become 
  clear(er) upstream of the front, with temperatures a few degrees 
  cooler than the very warm conditions expected Thursday. Forecast 
  temperatures Thursday through Friday are a blend of bias- 
  corrected statistical guidance. 
   
  The challenge then becomes what happens to the front as upstream 
  perturbations move eastward through the quasi-zonal midlevel 
  flow. This should result in a waffling (back-and-forth) of the 
  front in the Mid-Atlantic/Northeast upstream into the Ohio 
  Valley for the rest of the forecast period. Unfortunately, 
  accurate depiction of the timing/strength of these perturbations 
  (likely convectively reinforced) is quite challenging, and 
  operational models are showing quite a bit of spread in the 
  associated convective precipitation. Several rounds of 
  convection appear possible through the weekend north/west of the 
  CWA, but there are indications that we will get in on the action 
  by Saturday night (if not sooner).  
   
  One perturbation appears to initiate convection to our north  
  Friday night and Saturday, which may affect northern portions of 
  the CWA. This perturbation should draw the front northward  
  through much of the area by Saturday, allowing for warm max  
  temps. Convection may develop in the warm sector Saturday  
  afternoon, with another round of showers/storms Saturday night  
  in close proximity to the front. Convection and associated  
  mesoscale phenomena should drive the frontal placement  
  thereafter, and models are unsurprisingly in large disagreement 
  by Sunday as to where the front is located. The GFS appears to  
  be the most aggressive in the southward push, with the  
  ECMWF/CMC/ICON somewhat slower (to varying degrees). Generally  
  used a consensus blend for now, and kept chance PoPs through  
  Monday morning in much of the area. Best chances appear to be  
  Saturday night through Sunday night, but this will likely need  
  some geographic and temporal fine-tuning as the event  
  approaches. 
   
  Given the oscillating position of the front and the series of 
  perturbations moving along it Saturday to Monday, there is 
  potential for an axis of heavy rainfall. All operational models 
  show a swath of 1-3 inches in a lengthy corridor from the 
  northern/central plains to the Mid-Atlantic, but this corridor 
  has displacement of 150-300 miles model to model. The ICON  
  blasts the Mid-Atlantic with a 2-4 inch soaking by early next  
  week, with the GFS/ECMWF keeping the heavier precipitation to  
  our west and the CMC keeping it to our north (though all show  
  potential of 1+ inch of rain in the CWA during this time  
  window). Antecedent dry conditions suggest the flooding  
  potential is on the lower side compared to similar setups in the 
  past. Nevertheless, will need to keep a close eye on this  
  period, as pattern recognition suggests the ingredients are  
  available for heavy rainfall. 
   
  Severe potential is also non-negligible during this time frame, 
  with regionally maximized bulk shear in proximity to the 
  perturbations and near the front. In combination with diurnal  
  heating, sufficiently cool midlevels, and storm organization 
  (as suggested by model QPF/vertical motion fields), the 
  ingredients may be available for some strong to severe storms 
  during this time frame as well. 
   
  Models appear to show the front sagging to the southern CWA or 
  farther south early next week but also indicate potential for 
  upstream perturbations to allow for its return as the week 
  progresses. Timing discrepancies and the stagnant pattern that 
  develops necessitate keeping PoPs for the rest of the long term 
  (though capped at low chance) and maintaining fairly seasonal  
  temperatures during this period. 
   
  &&
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Cfa

Cfa

Posted
Posted
On 5/8/2018 at 11:07 AM, bluewave said:

It all depends on how strong of a positive or negative NAO/AO we get during the summer. The interaction with the other teleconnections is also important. The record low -AO in June-July 2009 combined with the -EPO to produce near record cool weather.The record -NAO influence in July 2015 was muted by a more +EPO. So we finished with a warm departure.

Thanks for the explanation.

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dWave

dWave

Posted
Posted

Sea breeze making it presence felt today...stronger/earlier than previous days. Just took a quick drop from 77 to 70 on a gusty south breeze.

If the sea breeze drops you to only around the avg high temp it can't be so bad. 

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bluewave

bluewave

Posted
Posted
1 hour ago, LongBeachSurfFreak said:

On of those days were I need a jacket for when I get home from work in the city. Definite marine influence. 

Cool feeling day out there with a SE flow and 58 degrees. Tough to bet against the marine influence when the SST's are still in the low 50's. Nice temperature spread this month between the 69.9 in NYC and 63.5 at ISP.

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