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Pittsburgh/Western PA Spring 2024


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Mesoscale Precipitation Discussion 0153
NWS Weather Prediction Center College Park MD
744 PM EDT Thu Apr 11 2024

Areas affected...portions of Pennsylvania, West Virginia, western
Virginia, and western Maryland

Concerning...Heavy rainfall...Flash flooding likely

Valid 112343Z - 120543Z

Summary...A focused axis of training convection is resulting in a
prolonged period of 0.25-1.00 inch/hr rates.  Areas of flash
flooding (locally significant) are likely to continue through 05Z.

Discussion...Recent convective trends have exhibited a focused
axis of convection extending from near BKW (Beckley, WV)
north-northeastward to near Pittsburgh Metro.  The band was
aligned with strong deep layer convergence on the western side of
strong, southerly 850mb flow over the Mid-Atlantic.  The band was
also oriented parallel to strong south-southwesterly steering flow
aloft and immediate downstream of a mid-level wave providing
forcing for ascent across the area.  500 J/kg SBCAPE and 1.3 inch
PW values were also located within the pre-convective airmass
across the region supporting the ongoing convection.  The net
result of the pattern was an elongated axis of 1-2 inch rainfall
totals over the past 3 hours (estimated per MRMS) along with
occasional spots of 1 inch/hr rates, all exceeding FFG thresholds
across the area and resulting in excessive runoff (locally
significant near the Pittsburgh area).

The ongoing scenario will persist over the next 4-6 hours, with
only a slow translation eastward of the band of convection during
that timeframe.  This will result in a continued risk of flash
flooding across the discussion area.  Although slight boundary
layer cooling may occur ahead of the band, ascent/cooling aloft
associated with the mid-level wave centered over Kentucky and
continued warm advection ahead of the band should maintain at
least 500 J/kg SBCAPE ahead of the convective band.  Ongoing flash
flood impacts are expected to continue through 05Z.

Cook

ATTN...WFO...BUF...CLE...CTP...JKL...LWX...MRX...PBZ...RLX...
RNK...

ATTN...RFC...LMRFC...MARFC...NERFC...OHRFC...SERFC...NWC...

LAT...LON   42077899 41977785 41117744 39457746 37927863
            36667984 36258102 37428231 38408286 39148216
            40438105 41138046 41917963

 

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The line around Slippery Rock looks vicious, but looks like Allegheny largely misses the worst as they slide south east.  Thats good to me, already lost power twice today with the, don't want to see damage or more rain at this point.  We just don't need it.

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3 minutes ago, Ahoff said:

The line around Slippery Rock looks vicious, but looks like Allegheny largely misses the worst as they slide south east.  Thats good to me, already lost power twice today with the, don't want to see damage or more rain at this point.  We just don't need it.

Yep works for me. Rather not deal with the wind and possibly losing power. Severe weather doesn't excite me like snow. 

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1 hour ago, north pgh said:

Storms still back building a bit into Ohio and slowly shifting south. I think we will still get some of this moving in after 10:00. Probably not severe though. 
A nice light show going on to our north :icecream:

Looks like a good call. Mother natures firework show lighting up the sky right now.

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Man the storm that hit us last night was wild. So much lightning my room was lit up. The rain and hail was so intense and loud.

If you zoom in you will see some pink to purple returns of 60-69dbz

ce60c546f5910f9c8da96fe9282a384c.jpg

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Now up to third place all time for April precipitation since 1836. The record is 9.27" from 1852, which was observed at Allegheny Arsenal in present-day Lawrenceville by the U.S. Army Signal Corps. The highest total since the formation of the Weather Bureau [now National Weather Service] is 8.11" in 1901 from the downtown city office. With about two weeks left in the month, the current tally is 7.63 inches. Surprisingly, it's been quite a while (1987) since we had an April on this list (although 1998 & 2011 saw 5.00" and 5.13" respectively).

image.png.cfcf53f3ba82cff2bca8f0684e1f1c27.png

Source: https://www.weather.gov/media/pbz/records/prec.pdf

 

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On 4/11/2024 at 9:06 AM, TheClimateChanger said:

Currently running 4.6F above normal for the month, with a mean temperature of 52.2F. A rather pedestrian [compared to some recent periods] 24th warmest overall in the threaded record, and 13th warmest at KPIT, for the first 10 days of April.

With the warm pattern in place, I projected forward through the 17th using the official NWS forecast for KPIT [with an adjustment for tomorrow for a likely midnight high temperature] and found the month to date mean temperature is projected to increase to around 55.9F by April 17th. Should that come to fruition, it would be the 5th warmest April 1 to April 17th period in the threaded record, and second only to 2010 at KPIT. Looks like a decent shot for a top 10 warmest April unless there is a cooldown at the end of the month.

This projection has worked out pretty good. Currently, PIT is at 55.1F for the MTD - up to ninth place. With today factored in, that should rise to around 55.8F, which would be good for 5th warmest for the MTD.

Also, up to third place on the YTD rankings in the threaded record. A full 0.5F warmer than 2012, and 0.6F warmer than last year.

image.png.5ad6bb25039c89c988b0c1fb9305f180.png

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MD 472 graphic

 

Mesoscale Discussion 0472
   NWS Storm Prediction Center Norman OK
   0112 PM CDT Wed Apr 17 2024

   Areas affected...extreme eastern IN...much of OH...and western PA

   Concerning...Tornado Watch 122...

   Valid 171812Z - 171945Z

   The severe weather threat for Tornado Watch 122 continues.

   SUMMARY...Storms moving into northwest OH may intensify the next 1-2
   hours. All severe hazards remain possible across Tornado Watch 122.
   A downstream watch will likely be needed in the next couple of hours
   across eastern OH into western PA.

   DISCUSSION...Convection has slowly intensified into early afternoon
   as storms move into a somewhat more unstable airmass. Stronger
   heating has allowed low-level lapse rates to steepen ahead of the
   line of convection. This will support potential for increasing
   gusts. Furthermore, low-level instability remains quite large, with
   0-3 km MLCAPE greater than 125 J/kg. Regional VWP data shows
   enlarged, and favorably curved low-level hodographs, and low-level
   rotation has been noted in velocity signatures via region radars.
   Further intensification of these cells is expected over the next
   couple hours across northwest into central Ohio. 

   As convection continues eastward, a similar environment is expected
   to extend across parts of eastern OH into western PA. A downstream
   watch will likely be needed by 20z/4pm EDT.

   ..Leitman.. 04/17/2024
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5 hours ago, TheClimateChanger said:

This projection has worked out pretty good. Currently, PIT is at 55.1F for the MTD - up to ninth place. With today factored in, that should rise to around 55.8F, which would be good for 5th warmest for the MTD.

Also, up to third place on the YTD rankings in the threaded record. A full 0.5F warmer than 2012, and 0.6F warmer than last year.

image.png.5ad6bb25039c89c988b0c1fb9305f180.png

If we compare this to some cities in the Upper South, you can see the last two years, this period has been about on par for what would have been deemed normal for the lower elevations of northeast Tennessee and southwest Virginia, and well within the limits of normal variability in a place like Knoxville, Tennessee. This is surprising to me because this is heavily weighted toward winter, which tends to be the time of the year when the south is much warmer than western Pennsylvania.

In the 30-year period from 1956-1985, only three years were warmer at Charleston, West Virginia [and only 5 were warmer than the same period in 2023 at PIT].

image.png.cdba11119796cb1f7be1abbb8d1bb324.png

Similar story at Roanoke, Virginia. Only 10 of 30 years had a warmer YTD than Pittsburgh in the period from 1956-1985. And last year too would have placed solidly around the median value.

image.png.75b6c0fcc02807e34a0b0d920e636c7d.png

In the Tri-Cities area of Tennessee, only 10 of 30 years had a warmer YTD than this year at Pittsburgh. And last year would have been around the median value.

image.png.5927257a436023fa5922e4909c2d6b5d.png

 

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2 minutes ago, TimB said:

Overperformed our way to a 3rd 80 at PIT today. None of the days were forecast to get there.

This time of the year, I feel like you've got to add a good 3-5 degrees to whatever they are forecasting to account for the lack of vegetation if there's any chance of appreciable sunshine. I'm sure once we get to summer, a lot of those 90-degree forecasts will stall at 88-89 though.

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