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Central Pa. Spring 2024


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With the 0.11" that fell here in East Nantmeal since midnight we are now up to 4.01" of rain since the month began on Monday. Some other area totals so far: Atglen 3.71" / Chester Springs 4.05" / Devault 3.76"/ Glenmoore 4.10" / Kennett Square 4.66" / Longwood Gardens 4.11" / West Bradford 4.67" / Nottingham 3.61"/ West Chester 4.51" / West Grove 3.69" / Warwick Twp. 3.99". Should finally see some sun today and tomorrow but still a chance of some showers and maybe some thunder w/ hail mixed in especially later this PM. Our below normal temps look to continue through the weekend before we finally see some milder weather by next week.

image.png.be2e3a79573b08c3dea6cc7b41f20ca8.png

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16 hours ago, Bubbler86 said:

I was not sure of that, they seemed a bit low. 

 

PS @Mount Joy Snowman thoughts on why all the NWS sites are seemingly lower than almost all the readings here?  

Low of 34 here and an additional 1.29" of rainfall brings my 3-day total to 4.26".  Quite an event.  Those upper level lows always carry surprises and we're not done yet.  Perhaps some graupel sightings today!

As to your question, let me first state that I trust nothing coming out of CXY haha.  But seriously, I don't see anything particularly "off" about those numbers.  I just think my area was a local hotspot for this event.  Now, this does lead me to an issue that I've been meaning to bring up to the board.  Does anyone else keep both an automated gauge and the classic inner/outer cylinder gauge for measuring rainfall, and if so, have you noticed that the automated gauges always under-measure, particularly during periods of lighter rain or drizzle?

Over the last year of using both styles, I've noticed that my automated gauge consistently under-measures by ~7-12%.  Take this event for instance, where we had many periods of heavy drizzle, my auto gauge only recorded 3.8" over the three days, whereas my official cylinder gauge captured 4.27".  Quite the discrepancy.  

It's interesting because obviously all of these NWS airport sites use automated collection canisters, correct?  Now, I'm sure their equipment is top-notch and calibrated regularly and scientifically approved and all that good stuff.  Also, my auto gauge is ever so slightly off-level.  Not by much at all, and not nearly enough to explain discrepancies that large, but it could explain some of it.  All of this is to say, I have no idea what the real story is haha.  I'm sure the NWS sites are accurate but I would be curious to know if anyone else keeps both styles of gauges?

Relatedly, a lot of those colorful accumulated precipitation maps that we like to throw around are based off of radar estimated precip.  Well, when you get events where the radar isn't capturing the strength of the rainfall (i.e. low clouds, easterlies, long periods of heavy drizzle, etc.) like we just experienced, the maps will be grossly underdone.

Just some food for thought.  Hope others can chime in.

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4 minutes ago, canderson said:

If any storms pop this afternoon  there is a pretty good shot at it hailing. 

I imagine we are looking at some pretty potent lapse rates in the lower atmosphere.  Could be a sneaky exciting day.  The sight of graupel always gets my juices flowing ha. 

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So  how does the last several months rank among the all-time wettest out here in Chesco?

For the December thru February months this season ranked as the 3rd wettest the top 5 being: 1978-79 = 21.37" / 1901-2 = 19.80" / 2023-24 = 18.83" / 1898-99 = 18.24" / 1909-10 = 18.18"


For the 4 month period December thru March this season ranked 2nd with the top 5 wettest being: 1898-99 = 25.90" / 2023-24 = 24.97" / 1993-94 = 24.86" / 1901-02 = 24.80" / 1978-79 = 22.88"

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41 minutes ago, Mount Joy Snowman said:

Low of 34 here and an additional 1.29" of rainfall brings my 3-day total to 4.26".  Quite an event.  Those upper level lows always carry surprises and we're not done yet.  Perhaps some graupel sightings today!

As to your question, let me first state that I trust nothing coming out of CXY haha.  But seriously, I don't see anything particularly "off" about those numbers.  I just think my area was a local hotspot for this event.  Now, this does lead me to an issue that I've been meaning to bring up to the board.  Does anyone else keep both an automated gauge and the classic inner/outer cylinder gauge for measuring rainfall, and if so, have you noticed that the automated gauges always under-measure, particularly during periods of lighter rain or drizzle?

Over the last year of using both styles, I've noticed that my automated gauge consistently under-measures by ~7-12%.  Take this event for instance, where we had many periods of heavy drizzle, my auto gauge only recorded 3.8" over the three days, whereas my official cylinder gauge captured 4.27".  Quite the discrepancy.  

It's interesting because obviously all of these NWS airport sites use automated collection canisters, correct?  Now, I'm sure their equipment is top-notch and calibrated regularly and scientifically approved and all that good stuff.  Also, my auto gauge is ever so slightly off-level.  Not by much at all, and not nearly enough to explain discrepancies that large, but it could explain some of it.  All of this is to say, I have no idea what the real story is haha.  I'm sure the NWS sites are accurate but I would be curious to know if anyone else keeps both styles of gauges?

Relatedly, a lot of those colorful accumulated precipitation maps that we like to throw around are based off of radar estimated precip.  Well, when you get events where the radar isn't capturing the strength of the rainfall (i.e. low clouds, easterlies, long periods of heavy drizzle, etc.) like we just experienced, the maps will be grossly underdone.

Just some food for thought.  Hope others can chime in.

On the point of your comment toward my question, in the central and southern LSV area, every NWS total is about .5 to .75" below almost the entire suite of reported figures on here (using the closest station to each report.)  It was not just your area; it was central and southern LSV wide.  If you take off CXY (though their yearly total is pretty consistent with the others) I would have thought most reports would have been between 3 and 3.75" while almost all were between 3.75" and 4.5".  Not often that every NWS station is below every local report.  Here is the updated COCO for compare though this has a flaw if the 7AM reporting is correct as it would include 7 hours of potential rain since midnight.  The gauge differences could explain it but that goes right back to questioning all measurements then.   People who use manual gauges also face the issue of being there to watch live and deal with evap. 

LNS: 3.72----14.61

MDT: 3.23----15.37

THV: 3.11----14.11

 

 

image.thumb.png.013ec695a4478c5863fc2e9d0f21e327.png

 

 

 

 

 

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33 minutes ago, Mount Joy Snowman said:

Low of 34 here and an additional 1.29" of rainfall brings my 3-day total to 4.26".  Quite an event.  Those upper level lows always carry surprises and we're not done yet.  Perhaps some graupel sightings today!

As to your question, let me first state that I trust nothing coming out of CXY haha.  But seriously, I don't see anything particularly "off" about those numbers.  I just think my area was a local hotspot for this event.  Now, this does lead me to an issue that I've been meaning to bring up to the board.  Does anyone else keep both an automated gauge and the classic inner/outer cylinder gauge for measuring rainfall, and if so, have you noticed that the automated gauges always under-measure, particularly during periods of lighter rain or drizzle?

Over the last year of using both styles, I've noticed that my automated gauge consistently under-measures by ~7-12%.  Take this event for instance, where we had many periods of heavy drizzle, my auto gauge only recorded 3.8" over the three days, whereas my official cylinder gauge captured 4.27".  Quite the discrepancy.  

It's interesting because obviously all of these NWS airport sites use automated collection canisters, correct?  Now, I'm sure their equipment is top-notch and calibrated regularly and scientifically approved and all that good stuff.  Also, my auto gauge is ever so slightly off-level.  Not by much at all, and not nearly enough to explain discrepancies that large, but it could explain some of it.  All of this is to say, I have no idea what the real story is haha.  I'm sure the NWS sites are accurate but I would be curious to know if anyone else keeps both styles of gauges?

Relatedly, a lot of those colorful accumulated precipitation maps that we like to throw around are based off of radar estimated precip.  Well, when you get events where the radar isn't capturing the strength of the rainfall (i.e. low clouds, easterlies, long periods of heavy drizzle, etc.) like we just experienced, the maps will be grossly underdone.

Just some food for thought.  Hope others can chime in.

There are typically differences between the electronic gauges and manual. I always default to the manual gauges...

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5 hours ago, Bubbler86 said:

On the point of your comment toward my question, in the central and southern LSV area, every NWS total is about .5 to .75" below almost the entire suite of reported figures on here (using the closest station to each report.)  It was not just your area; it was central and southern LSV wide.  If you take off CXY (though their yearly total is pretty consistent with the others) I would have thought most reports would have been between 3 and 3.75" while almost all were between 3.75" and 4.5".  Not often that every NWS station is below every local report.  Here is the updated COCO for compare though this has a flaw if the 7AM reporting is correct as it would include 7 hours of potential rain since midnight.  The gauge differences could explain it but that goes right back to questioning all measurements then.   People who use manual gauges also face the issue of being there to watch live and deal with evap. 

LNS: 3.72----14.61

MDT: 3.23----15.37

THV: 3.11----14.11

 

 

image.thumb.png.013ec695a4478c5863fc2e9d0f21e327.png

 

 

 

 

 

I scoured all the Cocorahs and WU stations that are within the vicinity of LNS, THV and MDT, and they all seem to be pretty much in line with the totals reported at those sites.  I think the NWS sites just happen to sit in localized spots that weren't hit quite as hard.  It happens.  We also aren't talking about much of a difference.  They are all still over 3" and LNS isn't far off from 4".  Chalk it up to randomness, me thinks. 

As for evaporation with manual gauges, I've actually tested that out and found that's it's virtually nonexistent.  I'm talking hot full sun summer days where I've purposely let the water sit in the gauge for days on end, and the amount lost is negligible.  I think it has to do with the gauge being mostly enclosed at the top and there not being any easy way for the water vapor to escape, which may be an added benefit of the funnel design.  Have I spent too much time thinking about the design mechanics of a weather gauge?  Yes.  Am I a weather weirdo?  Also yes.

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26 minutes ago, Itstrainingtime said:

That is correct- I actually had a few legitimate parachutes falling at the end of the 3 minute "event."

That action slid juuuuust by me to the north.  Missed it all.  I'm hopeful for the stuff approaching @Bubbler86's area.  Would be a travesty if I didn't get to see graupel today ha.

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19 minutes ago, Mount Joy Snowman said:

I scoured all the Cocorahs and WU stations that are within the vicinity of LNS, THV and MDT, and they all seem to be pretty much in line with the totals reported at those sites.  I think the NWS sites just happen to sit in localized spots that weren't hit quite as hard.  It happens.  We also aren't talking about much of a difference.  They are all still over 3" and LNS isn't far off from 4".  Chalk it up to randomness, me thinks. 

As for evaporation with manual gauges, I've actually tested that out and found that's it's virtually nonexistent.  I'm talking hot full sun summer days where I've purposely let the water sit in the gauge for days on end, and the amount lost is negligible.  I think it has to do with the gauge being mostly enclosed at the top and there not being any easy way for the water vapor to escape, which may be an added benefit of the funnel design.  Have I spent too much time thinking about the design mechanics of a weather gauge?  Yes.  Am I a weather weirdo?  Also yes.

True, but I did not see one report on here under 3.6".    The differences were even more stark going in to yesterday.  Nothing to do about it but it is a bit more serious of a discrepancy in my eyes. 

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