Western PA/Pittsburgh Spring Discussion 2021

[Ahoff]

57 minutes ago, TimB84 said:

Euro has us at 42 with rain next Saturday afternoon. The irony is that’s almost exactly where we were at the same time last year.

Mother's Day always seems to gave the worst weather.

[TimB]

4 minutes ago, Ahoff said:

Mother's Day always seems to gave the worst weather.

Indeed, May is one of those months that’s been consistently warm as a whole in recent years (except last year), but I can remember notably cold periods in the first half of every recent May except 2018 (the year all 31 days were above normal).

[Ahoff]

Looks like a gross, cold stretch coming up.  This is not welcome in May.

[TimB]

21 hours ago, Ahoff said:

Looks like a gross, cold stretch coming up.  This is not welcome in May.

It could be worse. Never forget:

[Ahoff]

4 minutes ago, TimB84 said:

It could be worse. Never forget:

Not convinced it doesn't get there at this point.

[TimB]

2 minutes ago, Ahoff said:

Not convinced it doesn't get there at this point.

Model trends already seem to be moving toward a seasonably cool pattern rather than anomalously cold junk like highs in the 40s. I know it’s setting the bar incredibly low to state that I think every day in this pattern will break 50 and that the low of 32 this past Saturday will be our last freezing temperature until at least October, but both do seem likely.

[Ahoff]

Looking at the models this morning, seeing possibly 4-7 days consecutively with highs in the 50s, into mid May, not appealing.

[TimB]

4 hours ago, Ahoff said:

Looking at the models this morning, seeing possibly 4-7 days consecutively with highs in the 50s, into mid May, not appealing.

Not saying I think May will average out below normal when it’s all said and done (I don’t), but warm weather fans in Pittsburgh have, as a whole, gotten to enjoy 10 out of the last 11 months and 57 out of the last 73. So it’s hard to look at a week-long stretch where temperatures run ~10 degrees below normal as all that bad. Except the rain nearly every day, that’s a different story.

[Mailman]

 

Mesoscale Discussion 0494
   NWS Storm Prediction Center Norman OK
   0147 PM CDT Mon May 03 2021

   Areas affected...portions of southern and eastern Ohio into West
   Virginia and southwestern Pennsylvania

   Concerning...Severe potential...Watch unlikely 

   Valid 031847Z - 032045Z

   Probability of Watch Issuance...5 percent

   SUMMARY...A couple of the stronger storms may pose a localized
   severe risk through the afternoon hours. A damaging gust or two are
   possible and a brief tornado cannot be completely ruled out. Given
   the sparse nature of the severe threat, a WW issuance is not
   anticipated.

   DISCUSSION...Convection has gradually deepened and become more
   widespread across portions of the Ohio Valley as a mid-level vort
   max traverses the region. Pockets of insolation have allowed for
   marginal destabilization of the boundary layer, with around 250-400
   J/kg MLCAPE currently realized (per latest Mesoanalysis). 18Z PBZ
   and RLX VWPs depict considerable veering of the sfc-500 m winds,
   with modest 0-3km speed shear all contributing to 150-300 m2/s2
   0-3km SRH, with 0-1km SRH values occasionally exceeding 200 m2/s2.
   Nonetheless, upper support is expected to remain modest, with low
   and mid-level lapse rates likely to remain below 6.5 C/km across
   most locations. While the favorable shear environment would support
   a damaging gust or a brief tornado with a stronger storm, the
   marginal instability is expected to limit the severe threat. Given
   the very sparse and brief nature of any severe threat that can
   materialize, a WW issuance is not expected.

   ..Squitieri/Grams.. 05/03/2021

[Ahoff]

3 hours ago, TimB84 said:

Not saying I think May will average out below normal when it’s all said and done (I don’t), but warm weather fans in Pittsburgh have, as a whole, gotten to enjoy 10 out of the last 11 months and 57 out of the last 73. So it’s hard to look at a week-long stretch where temperatures run ~10 degrees below normal as all that bad. Except the rain nearly every day, that’s a different story.

Well a week of 10 degrees below normal in May is something I consider bad.  It's not for me.  A week of 10 below normal in January sign me up, a week of 10 below normal in the Spring and Summer, no thank you.

[TimB]

17 hours ago, Ahoff said:

Well a week of 10 degrees below normal in May is something I consider bad.  It's not for me.  A week of 10 below normal in January sign me up, a week of 10 below normal in the Spring and Summer, no thank you.

You’re right, model trends seem to show this pattern being more persistent. GFS run after run with little or no 70s after today through the end of its run and the Euro doesn’t seem to want to bounce things back to seasonable mid-next week anymore either. I’d also rather have seasonably cool than unseasonably cold in May - unless we get at least a trace of snow, which doesn’t seem likely.

[Ahoff]

Just heard thunder!

[TimB]

Looks like the new normals were released today. Temps seem to be about half a degree or so higher for most parts of the year, and our new normal snowfall increased by over 2 inches to 44.1.

[TimB]

Also appears NWS Pittsburgh has confirmed the first tornado of the year. 

[RitualOfTheTrout]

3 hours ago, Ahoff said:

Just heard thunder!

Just sprinkles so far imby today. Think I've only heard thunder once this Spring which is unusual.

[TimB]

Longest streaks in May where the temperature failed to reach 60 in Pittsburgh:

1. 5/2-5/13/1917 (12 days). 
2. 5/4-5/12/1954 (9 days). 
3. 5/6-5/13/1989 (8 days). 
T-4. 5/8-5/14/1960 (7 days). 
T-4. 5/3-5/9/1929 (7 days). 
6. 5/5-5/10/1947 (6 days). 
T-7. 5/1-5/5/1921 (5 days). 
T-7. 5/11-5/15/1878 (5 days). 
T-7. 5/1-5/5/1908 (5 days). 
T-10. 11 streaks of 4 days, most recently in 2005, 2002 and 1994

Some of these are part of longer streaks that started in April, but I’m only counting the May days in those streaks.

[Ahoff]

The NWS updated the averages for each month and it reflects in their monthly reports.  Every month looks to have gotten cooler relative to normal.  April, for example went from slightly above average last week to slightly below with the new figures released.

[TimB]

13 hours ago, Ahoff said:

The NWS updated the averages for each month and it reflects in their monthly reports.  Every month looks to have gotten cooler relative to normal.  April, for example went from slightly above average last week to slightly below with the new figures released.

Well there goes my “10 months out of the past 11” narrative.  That said, I absolutely think it’s reasonable to compare the April 2021 temperature to the 1991-2020 normals. (To the extent that moving the goalposts every ten years is reasonable in and of itself.) Not sure we can or should retroactively apply the 1991-2020 normals to temperatures observed last year or before, but September and December 2020 would also be below the 1991-2020 normal. 

[TimB]

The PTSD is strong with this one. Good thing it’s May and not January so there’s nothing to be bummed out about.

[TimB]

Guess what’s made it into the point & click for parts of Allegheny County.

[Ahoff]

Absolutely sickening.  This May could be worse than last year, as it doesn't seem to want to get to even 65 anytime soon.

Plus, I think we can put drought concerns to bed.

[TimB]

19 hours ago, Ahoff said:

Absolutely sickening.  This May could be worse than last year, as it doesn't seem to want to get to even 65 anytime soon.

Plus, I think we can put drought concerns to bed.

Some runs of some models have us soaring into the 60s in the warm sector tomorrow night just before midnight (I’d bet on that based on climo). Otherwise I got nothing.

[Ahoff]

1 hour ago, TimB84 said:

Some runs of some models have us soaring into the 60s in the warm sector tomorrow night just before midnight (I’d bet on that based on climo). Otherwise I got nothing.

"soaring" lol.  Average high is 70 at this point.  Be interesting to see how cold this May ends up, because it would take many days in the 80s and maybe even 90s at the end of the month to turn it arpound once this cold breaks.

[TimB]

1 hour ago, Ahoff said:

"soaring" lol.  Average high is 70 at this point.  Be interesting to see how cold this May ends up, because it would take many days in the 80s and maybe even 90s at the end of the month to turn it arpound once this cold breaks.

Remember last year? We sure made a run for it and ended up less than two degrees below average despite the 2nd coldest first two weeks of May on record. And through one week of May we’re running 4.5 degrees ahead of last year. Today is warmer than last May 8th and tomorrow will be warmer than last May 9th, so I think below average is still more likely than above average when it’s all said and done, but never say never.

Edit: of course that was a -1.9 anomaly against the normals that were in place at the time. Would have been a -3.0 anomaly against the new normals, since May is one of the months that warmed the most.

This cold snap will be remembered maybe not for being brutally cold, but for its longevity. Even in that brutally cold first half of May last year, we never strung together three consecutive days where we didn’t get to 60. Today is day 4 of that streak. But we had some record cold last year and we’ll fall way short of that this year (though Wednesday’s record low of 33 is fairly soft and I wouldn’t rule out getting close to that).

[Ahoff]

4 hours ago, TimB84 said:

Remember last year? We sure made a run for it and ended up less than two degrees below average despite the 2nd coldest first two weeks of May on record. And through one week of May we’re running 4.5 degrees ahead of last year. Today is warmer than last May 8th and tomorrow will be warmer than last May 9th, so I think below average is still more likely than above average when it’s all said and done, but never say never.

Edit: of course that was a -1.9 anomaly against the normals that were in place at the time. Would have been a -3.0 anomaly against the new normals, since May is one of the months that warmed the most.

This cold snap will be remembered maybe not for being brutally cold, but for its longevity. Even in that brutally cold first half of May last year, we never strung together three consecutive days where we didn’t get to 60. Today is day 4 of that streak. But we had some record cold last year and we’ll fall way short of that this year (though Wednesday’s record low of 33 is fairly soft and I wouldn’t rule out getting close to that).

I just looked today, it says we were 3 degrees below average for May last year.

 

And that's the point, longevity.  If this lasts three weeks and has 8-12 degrees below average on many days, it will be colder than last. May.

Only positive about last May, was that it was dry.  This one doesn't seem to have that going for it so far.

[TimB]

4 hours ago, Ahoff said:

I just looked today, it says we were 3 degrees below average for May last year.

 

And that's the point, longevity.  If this lasts three weeks and has 8-12 degrees below average on many days, it will be colder than last. May.

Only positive about last May, was that it was dry.  This one doesn't seem to have that going for it so far.

Relative to 1991-2020. -1.9 relative to the 1981-2010 normals that were in place at the time. Regardless, we had a very warm back half of the month which is of course no guarantee this time.

[Ahoff]

10 hours ago, TimB84 said:

Relative to 1991-2020. -1.9 relative to the 1981-2010 normals that were in place at the time. Regardless, we had a very warm back half of the month which is of course no guarantee this time.

Yeah 1991-2020 average makes more sense to compare May 2020 to rather than 2010 averages.

[TimB]

12 minutes ago, Ahoff said:

Yeah 1991-2020 average makes more sense to compare May 2020 to rather than 2010 averages.

I could make a case for either one being logical and am genuinely curious where the meteorological community stands on that one.

[Ahoff]

1 hour ago, TimB84 said:

I could make a case for either one being logical and am genuinely curious where the meteorological community stands on that one.

For me, it makes sense that at the end of that period it makes more sense to compare it to the same year.  2020 to 2020.

 

Anyway looks like 40s an rain all day, welcome to March guys.

[Ahoff]

Looks like radar says heavy snow in the Grove City area.  Gross.