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May 2022 Thread


weatherwiz
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4 minutes ago, LibertyBell said:

Yep where that ring of fire hit the NE, there were some amazing convective events.  The front sometimes just stalled over C PA to upstate NY, while it baked east of there.  And going further west, the rains and flooding near St Louis was historic.

 

ahhh that's right...that was some epic historic flooding along the Mississippi/Missouri Rivers in 1993. 

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1 minute ago, Typhoon Tip said:

Funny you mentioned that ... I'm already noticing that happening...

The front that ends our "two day" heat wave, has normalized some comparing the original modeling cinema from 4 .. 5 days ago.  The upper support even goes more zonal in the non-hydrostats instead of trough incursion that yo-yos in and out...etc.  In fact, centered on ~132 hours out from the 00z run cycle, all the models attempt even bounce the height back, already...by as early as Tuesday... However, because of idiosyncrasies over eastern Canada, we end up with high pressure at the surface retreat E of NF ..which sends NE trajectories back SW under the upper heights - so it's a dud, gutted ridge.  But, the 850 mbs do reflect muted overall aspect, by only on average coming down to 9 to 12 C through the period.  

Then there's suggest from another flat trough and whisky front.  Then, I'm tracking a much bigger systemically anchored heat look that's really quite awesome already in the 300 hour EPS/GEPs... The GFS is more tepid but it's own PNA is down below -1 SD by Mem Day weekend, which suggests room to negatiate.   

Yup...upper support certainly appears to go more zonal, meanwhile looks like the front becomes parallel to the mid-level flow. That alone would slow down the progression of the front but when you add in the upper support going more zonal and being displaced farther west from the front...that results in the tug back. 

If you look at the models tomorrow evening and watch the QPF field there are some rather interesting conclusions which can be drawn. This is shown really well on the CAMs but you get a line which develops just ahead of the front but the line actually appears to retrograde back to the northwest. 

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1 minute ago, weatherwiz said:

Yup...upper support certainly appears to go more zonal, meanwhile looks like the front becomes parallel to the mid-level flow. That alone would slow down the progression of the front but when you add in the upper support going more zonal and being displaced farther west from the front...that results in the tug back. 

If you look at the models tomorrow evening and watch the QPF field there are some rather interesting conclusions which can be drawn. This is shown really well on the CAMs but you get a line which develops just ahead of the front but the line actually appears to retrograde back to the northwest. 

That might be what separates this from May 1996 heat.  That year we went to a warm humid summer with no 90s until the last day of August (the total opposite of August 1995 when we had no rain the entire month until the last day of the month!)  In May 1996 that was pretty much it for the heat for the whole year.

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3 hours ago, Sey-Mour Snow said:

Euro upping the ante from BDL to southern NH.  Widespread 95-100.. Dews in the lows 70s down here with low 90s.

 

 

 

ecmwf-deterministic-massachusetts-t2m_f_max6-3177600.png

ecmwf-deterministic-massachusetts-t2m_f_max6-3264000.png

Yeah... (thanks)

I noticed that all models are slowing the front now to Sunday night.    4 or 5 days ago, the original vision for this weekend was more like a Saturday shot - the deep layer circulation features toting that front along where stronger and thus faster.

The funny thing is, I didn't mentioned this but I was internally voicing that the models, all of three majors, have a magnification' ( over amping) tendency for events that 'rise over the temporal horizon' of the outer modeling frames.  It's something I've op-ed about in longer posts that by virtue of being too long and annoying, may not have been read - haha.  What can I say - that's how I roll. 

Anyway ... it's like the S/W and associate front as well as the overall pattern manifold was 'logistically effected' by too much westerlies mechanics that these models tend to apply to the field ...and now that we are getting closer, it's a shallower wave. The ridge is more resilient that way... More resilience means more W motion to the level trajectory, and that's moving the wind dial from SW to more WSW and that makes big difference in maximization...  As well, another positive feedback, causing more 'synergistic' heat, is that mechanical give back to the ridge is driving a hotter kinetic layer through the 900 to 700 mb level. That's +22.5 C inside that plume astride the SNE coast Saturday evening, a pocket that wasn't there at 12z - that means the the lower troposphere was plumbed and overturned by mixing... I don't know how that can happen without the adiabats also being extrapolated from 850 or even exceeding that sigma level. 

In short, I still think that 101 is possible at Hanscom Field, Rt 9, and over down town thoroughfares.  Possible - as it, 'monitoring the potential for'

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44 minutes ago, weatherwiz said:

Yup...upper support certainly appears to go more zonal, meanwhile looks like the front becomes parallel to the mid-level flow. That alone would slow down the progression of the front but when you add in the upper support going more zonal and being displaced farther west from the front...that results in the tug back. 

If you look at the models tomorrow evening and watch the QPF field there are some rather interesting conclusions which can be drawn. This is shown really well on the CAMs but you get a line which develops just ahead of the front but the line actually appears to retrograde back to the northwest. 

Yeah ...I mentioned this last night with Tiger'  ... The NAM shows elevated heat - almost like a hybrid EML arriving, between 900 and 850mb levels, during tomorrow late afternoon and night. Meanwhile, the surface T1 in the grid is still hung up in the mid 60s while that advection occurs.  Like d(t) is +7 to 11 at 900 mb, rising from 13 or so at 4pm Friday, to 24C 11 pm Friday night.

It's not clear to me that overrunning of 20+C air is going to happen without some sort quasi-warm frontal slantwise rise motion ... does it then breach free convection - i.e., elevated warm IB driven frequent lightning overnight/downpours strafing through...

The caveat is the this SW/ Texan heat released air appears to be - perhaps - too early in the season?  Whatever the reason, it's not clear it is theta-e charged. I mean, if this were coming in with a layer/slab of elevated DP off the deck, with some of that dry EML overtop, we'd probably see some of that isentropic lift action more obviously?  

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'Wiz

doing it the old fashioned way with the NAM grid over here...   BOS/LGA

36000936454 03704 171915 66151712   36000995933 01993 151616 71142114
42000987647 -3494 161921 69131913   42002995640 05294 141709 74162417
48001975155 -1696 162214 73162317   48000984153 02695 172608 73172417
54000533228 00893 152409 76292419   54000583233 -1094 172208 75272718
60000522629 -0592 162310 76302319   60000542927 -0793 172211 75282418

I don't know if you know how to interpret these (FOUS) grid values, but as per my own pre reqs for Met back in the day, we used them regularly.  Back then it was the NGM and the ETA, respectively.  But now it's just the NAM...

Anyway the two lines I bold show that the warm air burst, overtop synoptically, prior to the llvs catching up. That's by definition WAA... But here we see minor QPF of .01 and .02 respectively - which isn't insignificant when knowing what is going on synoptically to induce these numbers.  The +23 and +24 C, between 2 am and 8 am Saturday morning, while it is +16 C in the low levels...etc..  You can also see the wind at both BOS and LGA go from S to WSW, and the sounding becomes adiabatic to surface ( or closer to it) under that warm layering upon the next interval?  That's a warm fropa there.

Anyway, I would not be surprised if there's frequent lightning predawn elevated stuff... and then look at the RH later in the day!!  Bone dry after that morning advection clears, full sun and soars to 30C in the T1 at Logan.    That's 34 or 35 C in the 2-meter (most likely)

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7 minutes ago, Typhoon Tip said:

'Wiz

doing it the old fashioned way with the NAM grid over here...   BOS/LGA

36000936454 03704 171915 66151712   36000995933 01993 151616 71142114
42000987647 -3494 161921 69131913   42002995640 05294 141709 74162417
48001975155 -1696 162214 73162317   48000984153 02695 172608 73172417
54000533228 00893 152409 76292419   54000583233 -1094 172208 75272718
60000522629 -0592 162310 76302319   60000542927 -0793 172211 75282418

I don't know if you know how to interpret these (FOUS) grid values, but as per my own pre reqs for Met back in the day, we used them regularly.  Back then it was the NGM and the ETA, respectively.  But now it's just the NAM...

Any the two lines I bold show that the warm air burst, overtop synoptically, prior to the llvs catching up. That's by definition WAA... But here we see minor QPF of .01 and .02 respectively - which isn't insignificant when knowing what is going on synoptically to induce these numbers.  The +23 and +24 C, between 2 am and 8 am Saturday morning, while it is +16 C in the low levels...etc..  You can also see the wind at both BOS and LGA go from S to WSW, and the sounding becomes adiabatic to surface ( or closer to it) under that warm layering upon the next interval?  That's a warm fropa there.

Anyway, I would not be surprised if there's frequent lightning predawn elevated stuff... and then look at the RH later in the day!!  Bone dry after that morning advection clears, full sun and soars to 30C in the T1 at Logan.    That's 34 or 35 C in the 2-meter (most likely)

There's definitely some opportunity for some elevated convection to pop tomorrow evening. Actually, we could even see thunderstorms moving through during the afternoon. Some models hint at the MCV which develops later this evening within the OV maintaining and moving across our region during the day. 

But tomorrow night we have the nose of the EML moving in, ample elevated CAPE, and a pretty solid theta-e ridge off to the west. Could certainly see some strong storms pop with the risk for small hail. 

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Looking over/analyzing the NAM's sounding...

I think it is too shallow with the BL depth, given this synopsis through the weekend.   MET machine guidance was only 92 at KFIT/KASH/KBED which appears to low-ball a +21.5 overriding 850  mb metric - particularly when the wind is 240 deg at 10 to 15 kts in mid BL flow.  That wind trajectory offers 0 marine/Serly contamination.  Meanwhile, the the RH% at/below 500 mb all the way down are < 50%, under a climbing late May sun. 

It's definitely low balling the temps.  Why?   Well ...off the bat, it appears it is limiting the mixing depth/BL heights to just 900 mb level.  

One thing I have noticed about the NAM is that it T1 ( 20 mb above station sigma) is typically cold biased beyond 48 hours.  As that intervals in question get nearer over consecutive runs, it adds whole degrees C to that T1 value - particularly outside of deep CAA times of year.  This whole situation with a sudden jolt into a + standard deviation heat event, then added to that tendency, I think is exaggerating that effect.

92 is too cool on Saturday ( MET)... 88 at Logan is ungood forecasting - 

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4 minutes ago, dendrite said:

GFS is beefing up the dews and slightly lowering the temps as well. I figured that would happen come go time.

Seems par for the course in these.  Models are too hot and too dry.  Start subtracting from T and add it to the Td.

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11 minutes ago, Typhoon Tip said:

that thing in southern Missouri looks suspiciously like a landphoon

May have to watch for some storms Friday night on the leading edge of the EML with that convectively induced vort.

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6 hours ago, LibertyBell said:

Wow so 100+ in three different heat events?  That must be highly unusual.

I'd like to see what caused the peak of that summer to only reach 103 at Central Park, while it was 104 at JFK, 105 at EWR and 107 at LGA.  Somehow NYC ended up at the back of the pack.

 

Some have postulated that trees getting taller/bushier have impacted Central Park obs, but I don't think that was nearly as much of a factor 56 years ago.  Airports tend to be hotter anyway because it's harder to distance the instruments from the tar.  Central Park itself is hotter than the official NYC site thru 1960, Battery Place, near the south end of Manhattan.  (And I'd love to access those old records - for instance, where SPK has 3/1888 as 21" all on 3/12, BP has snowfall over 3 days, 3/12-14: 16.5/3/0/1.4, which more closely jives with written descriptions of the blizzard.  BP also was measuring temps to 0.1°, greatly limiting ties.)

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36 minutes ago, tamarack said:

Some have postulated that trees getting taller/bushier have impacted Central Park obs, but I don't think that was nearly as much of a factor 56 years ago.  Airports tend to be hotter anyway because it's harder to distance the instruments from the tar.  Central Park itself is hotter than the official NYC site thru 1960, Battery Place, near the south end of Manhattan.  (And I'd love to access those old records - for instance, where SPK has 3/1888 as 21" all on 3/12, BP has snowfall over 3 days, 3/12-14: 16.5/3/0/1.4, which more closely jives with written descriptions of the blizzard.  BP also was measuring temps to 0.1°, greatly limiting ties.)

Wow I've heard that the March 1888 blizzard was undermeasured at Central Park.  This really makes me wonder if this was the case and to see what other local snowfall measurements were around the area.  I've also heard that a few years before snowfall measurements started being officially kept at Central Park, NYC actually had close to 100 inches of snow in the 1860s, I would love to see what stations in the area were keeping records back in the 1800s and what they had for that year.

 

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12 minutes ago, powderfreak said:

Another 0.42” of steady synoptic rain so far today.

What a wet 5-6 days.

49F outside and the heat on inside.  This time of year is wild in one day your boiler is going and the next day it’s 90F with A/C.

I turned the heat back on earlier today. It’s really looking lush out there, we’ll below 2500’. 

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