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E PA/NJ/DE Spring 2022 OBS Thread


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I thought I would share a post from my Chester County PA Facebook Weather Site that arose from some farmer questions around the growing season and the relations to the relative elevation differences across the county. Along with an understanding of the differences between frost and freezes.

This is going to be a pretty lengthy post as I started looking at some questions I received on frost vs. freeze and the growing season here in Chester County. First off I want to be sure everyone knows the difference between frost and freeze. Frost occurs when the temperature on the ground level reaches 32 degrees. However, the National Weather Services and trained COOP observers and spotters are required to measure the actual air temperature at 5 to 6 feet above the ground level. Therefore, it is easy to measure freezing temperatures based on weather observation records. Frost however can occur with temperatures in the upper 30's so records are not as robust for frost observations....unless it was reported in the notes section of weather observer reports. There are also significant differences based on elevation above sea level. Higher elevations across our county experience less frost and fewer freezing days as cold air is heavier and sinks into valley locations. This is why on calm and clear nights there can be a 5-to-10-degree difference over a mile...with temperatures lower and frost and freeze conditions more common at lower spots vs. higher locations.

Here in Chester County, we range from the highest elevation of 1,071 ft. in the Welsh Mountains across Honey Brook Township...to the lowest elevation of 70 feet above sea level along the Schuylkill River at the Montgomery County line. The primary weather records I use are from Coatesville NWS Coop observers (1894-2003) and East Nantmeal Township (2003 to Present). The weather records from the NWS COOP observers between 1894 through 1982 were recorded in Coatesville at an elevation between 350ft and 400 ft above sea level. All observations since 1983 at both Coatesville and East Nantmeal have been taken between 650 ft to 685 ft above sea level. Due to this when I compare actual to average temperatures I use the higher elevation temperature averages for Chester County from 1983 to Present. This will be the 40th year of high elevation records. For all-time records (including temperature, rain, and snow) I use the combined records from 1894 to Present.

Overall, the average annual temperature readings from 1894 through 1982 compared with 1983 through 2021 period are almost exactly the same! This, despite our current warming phase of our cyclical climate changes. As expected average high temperatures are more than 1 degree colder when analyzing the higher elevation observations from 1983 through today - with low temperatures averaging almost 2 degrees warmer than the lower spots ran from 1894 to 1983. Overall average annual temperatures from the first 89 years of obs from 1894-1982 had an average annual temperature of 52.2 degrees - compared with the 1984 through 2021 period having an annual average temperature of 52.5 degrees...so only 0.3 degrees warmer.

 

Now due to the differences in elevation the growing season has shown a much greater difference compared to the overall temperature profiles when you compare the higher spots over 650 feet to the lower spots below 400 feet in our County. The near 2 degrees of low temperature warming due to the higher elevations along the ridges has resulted in a 2 week increase in the growing season comparing ridge vs. valley locations (172 days in the valley vs 186 days on the ridges). There is a one week or greater difference between both the last freeze of the spring (April 18th (ridge) vs April 25th (valley) and the first freeze of the fall (October 14th (valley) vs. October 24th (ridge). Of the 89 years of valley observations from 1894-1983 our last freeze in spring occurred in April a total of 60 times (68%) vs. 29 times in May (32%). On the ridges since 1983 our last spring freeze has occurred in April a total of 33 times (84%) compared to 3 times in both May (8%) and March (8%). Let me know if any questions or follow ups to any of the above information.

Thanks again for your tremendous support and participation on this site!! It is deeply appreciated!!

 

Sincerely, Paul

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9 hours ago, RedSky said:

Can't wait until June when it gets warm... May looks like it could be -5F top ten coldest

 

I'm all for delaying the sweaty season as long as possible. Made it to 62.2°F here today with some sprinkles between 2-3PM. Tomorrow looks like fantastic grilling weather, and I've got some butterflied chicken breasts marinating in several different marinades, ready to go on the grill as soon as I'm done mowing my lawn tomorrow.

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Red Flag Warning was lofted -

Quote

Red Flag Warning

URGENT - FIRE WEATHER MESSAGE
National Weather Service Mount Holly NJ
359 AM EDT Thu Apr 28 2022

NJZ001-007>010-012>015-017>020-022-025>027-PAZ054-055-060>062-070-
071-101>106-281700-
/O.UPG.KPHI.FW.A.0001.220428T1600Z-220429T0200Z/
/O.NEW.KPHI.FW.W.0001.220428T1500Z-220429T0200Z/
/O.CON.KPHI.FW.A.0002.220429T1300Z-220430T0200Z/
Sussex-Warren-Morris-Hunterdon-Somerset-Middlesex-
Western Monmouth-Eastern Monmouth-Mercer-Gloucester-Camden-
Northwestern Burlington-Ocean-Atlantic-Coastal Atlantic-
Coastal Ocean-Southeastern Burlington-Carbon-Monroe-Berks-Lehigh-
Northampton-Delaware-Philadelphia-Western Chester-Eastern Chester-
Western Montgomery-Eastern Montgomery-Upper Bucks-Lower Bucks-
359 AM EDT Thu Apr 28 2022

...RED FLAG WARNING IN EFFECT FROM 11 AM THIS MORNING TO 10 PM
EDT THIS EVENING FOR LOW RELATIVE HUMIDITIES AND GUSTY WINDS FOR
MUCH OF NEW JERSEY AND EASTERN PENNSYLVANIA

...FIRE WEATHER WATCH REMAINS IN EFFECT FROM FRIDAY MORNING
THROUGH FRIDAY EVENING FOR LOW RELATIVE HUMIDITIES AND GUSTY WINDS
FOR MUCH OF NEW JERSEY AND EASTERN PENNSYLVANIA...

* AFFECTED AREA...Sussex, Warren, Morris, Hunterdon, Somerset,
  Middlesex, Western Monmouth, Eastern Monmouth, Mercer,
  Gloucester, Camden, Northwestern Burlington, Ocean, Atlantic,
  Coastal Atlantic, Coastal Ocean, Southeastern Burlington,
  Carbon, Monroe, Berks, Lehigh, Northampton, Delaware,
  Philadelphia, Western Chester, Eastern Chester, Western
  Montgomery, Eastern Montgomery, Upper Bucks and Lower Bucks.

* TIMING...Daytime today (for the Red Flag Warning) and daytime
  Friday (for the Fire Weather Watch).

* WINDS...Northwest 15 to 25 mph with gusts up to 35 mph.

* RELATIVE HUMIDITY...As low as 17 percent.

* TEMPERATURES...In the upper 40s to mid 50s today and upper 50s
  to low 60s on Friday.

* IMPACTS...Critical fire weather conditions expected. Increased
  risk for rapid wildfire growth and spread. Prescribed burns
  may get out of control.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now, or will shortly due to a combination of
strong winds, low relative humidity, and dry fuels. Any fires
that develop may quickly get out of control and become difficult
to contain.

A Fire Weather Watch means that critical fire weather conditions
are forecast to occur due to a combination of strong winds, low
relative humidities, and dry fuels. Listen for later forecasts
and possible Red Flag Warnings.

For more information about wildfire danger, burn
restrictions, and wildfire prevention and education, please visit
your state forestry or environmental protection website.

&&

$$

 

 

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1 hour ago, CoolHandMike said:

Winds are already howling too. I'm supposed to be out in it again but I'm taking a sick day. Hoping my head cold is just that.

Watching Fox29 they are going with 35+ wind gust today, 25+ tomorrow and 20+ Saturday so a couple more days.

My head feels like it weighs 100 lbs. Not sure if it's allergies or some sort of cold like yourself...

37F

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4 hours ago, Birds~69 said:

Watching Fox29 they are going with 35+ wind gust today, 25+ tomorrow and 20+ Saturday so a couple more days.

My head feels like it weighs 100 lbs. Not sure if it's allergies or some sort of cold like yourself...

37F

Mine came on all of a sudden like an allergy attack Tuesday afternoon, but it's lingering like a cold this morning. Sudafed and Mucinex are the only things keeping me from feeling like absolute crap. Hope you get better soon.

Looks like sustained 10-15mph with occasional gusts nearing 20 imby. Currently just under 50°F, bright and sunny, though this morning before the sun was up I was getting late fall vibes.

 

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CFS is forecasting a -5F May 

Going by the completely obliterated southeast ridge since the spring equinox it's believable

The next far below normal cold intrusion is already on the radar for the first full weekend in May. Like clockwork since early January the most stable repeating pattern I think I have ever seen.

 

 

 

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41 minutes ago, RedSky said:

CFS is forecasting a -5F May 

Going by the completely obliterated southeast ridge since the spring equinox it's believable

The next far below normal cold intrusion is already on the radar for the first full weekend in May. Like clockwork since early January the most stable repeating pattern I think I have ever seen.

 

Accu weather at noon going w/below normal May 5-11...

51F

aw.jpg

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