Sunday, October 25, 2020

Some Weather Notes on a Chilly, Rainy Sunday Afternoon In Late October Ahead of Another Highly Likely Functionally Non-Existent Winter

Forested tract in the unincorporated CDP called Croom, Prince George's County, Md., 1:36 p.m. Oct 24, 2020

A very good friend of mine -- indeed, my best friend -- owns a large parcel of land there and we visited it yesterday. There are two more pics from that visit below.


The long and storied history of Prince George's County, Md., back into Colonial (and pre-Colonial) times really is under-appreciated. This is due, at least in part, to what a mess the Washington, D.C.-fringing parts of the county are today.

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Saturday early afternoon on a chilly, rainy October day.

At the noon hour, it is 48F with 43F dew point at KDCA with light rain and a 10 mph northly breeze. So, far there has been 0.43" of rainfall since about 3 a.m.

For KBWI, the air temp / dew point values are 49F and 39F and overcast with a 9 mph northeasterly breeze. So, far there has been just 0.08" of rainfall since about 3 a.m.

Per the 10:16 a.m. LWX area forecast discussion, there is a shortwave crossing the southern Appalachians with isentropic ascent and warm advection atop a cold air wdge that has triggered rainfall.

NWS high-resolution surface weather map for a portion of the eastern U.S., 12Z 25 October 2020

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A high over Quebec responsible for the Appalachian leeside damming is keeping drier air in place to the northeast -- hence the drier conditions even as nearby as KBWI.

Without going into a lot of detail, here is the synopsis: A cold front will stall to the south through tonight before returning north as a warm front Monday. Another cold front will move into the area Tuesday and it will stall out nearby through Friday.

NWS high-resolution surface weather map for nearly the entire Lower 48 U.S., 12Z 25 October 2020

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The remnants of what is now Tropical Storm Zeta -- yes, we are into the sixth letter of the Greek alphabet this hurricane season in the Atlantic basin -- and another low pressure may track along the boundary, possibly impacting the D.C./Baltimore area Wednesday night through Friday. High pressure will likely return for next weekend.

NWS U.S. weather advisories with legend, updated
1614 UTC 25 October 2020

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There is a complex weather system pulling out of the Rockies into the Great Plains that is bringing the first heavy snowfall of the season across the Colorado Rockies and into the western High Plains of Nebraska and Kansas.

As the satellite image (still frame) below shows, it is cloudy today over a vast swath of the Lower 48 United States. This is in contrast to those many September and October days when it is clear coast-to-coast.

GOES East GeoColor satellite image for Lower 48 U.S. and adjacent regions, 1556 UTC 25 October 2020

The dark area in the western Pacific is simply nighttime "vanishing" to the west.

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As ever, it remains very dry and breezy in the Western U.S., judging by the NWS advisory map and the colors across California.

At least for California, the presence of the gargantuan Pacific Ocean really is a total waste for California ...

NWS WPC NDFD surface weather map forecast with fronts and type and likelihood of precipitation, looped in six and hour hour increments, 18Z 25 Oct - 12Z 27 Oct 2020

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Back here, this is the first day since last Sunday in which the temperatures -- both daytime and especially nighttime -- are not noticeably above normal. Not only were there six days featuring highs of at least 72F, but five of those were 75F or greater to include 80F on Thursday (Oct 22nd).

As for overnight lows, forget it: In the present era, they are always way above some NWS notional 30-year average (which, by the way, gets updated next year from 1981 - 2010 to 1991 - 2020). And it's always so damn humid in this part of the world.

Just for the record, the October 2020 month-to-date overall average temperature departure at KDCA is running +3.0F, so it's not a huge warm anomaly.


Looking ahead to the winter, there is strong evidence -- as shown in the assortment of long-range models run by NASA and NOAA -- that the period of Dec 2020 / Jan 2021 / Feb 2021 is going to feature a Northern Hemisphere winter very similar to last year.

What follows below are a series of graphical outputs of global 2-meter (surface) temperature anomalies for the three-month period of Dec 1, 2020 - Feb 28, 2021 corresponding to Northern Hemisphere climatogical winter as produced in a series of runs done at least several weeks ago. (I got the screen shot of these runs from Gary.)

North American Multi-Model Ensemble (NMME) showing global 2-meter temperature anomaly for NH climo winter 2020-'21 including probabilistic forecast.

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What that means is a super-stable Arctic polar vortex that almost never "leaves" its source region -- with basically no Arctic outbreaks / incursions across the middle latitudes of North America, and hence, like last year, functionally no winter here.

Other models including GEM-NEMO, GFDL's FLOR, NASA/GSFC GEOS-5 v2, and IMME showing the same 2m T anomaly forecast for NH climo winter 2020-'21

The details over the (rapidly warming) Arctic differ, but all are screaming the same thing: NO WINTER in much of the Lower 48 United States.

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The strong odds are there will be one "winter episode" in, like, late November, and then nothing until late April when the polar vortex undergoes its seasonal breakup -- and then a late-season Arctic outbreak at a time when nobody wants it.

More global model alphabet soup -- NCEP GFS v2, CanCM4i, GFDL's CM 2.1, and NCAR's CCSM4.0 -- showing the same damn thing.

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The weather aside, I really don't want to get into a detailed entry right now. I'd like to go to Old Town Alexandria -- probably back to O'Connell's -- for a few hours this afternoon.

As a follow-up to the topic in my previous entry, I've made an urgent care appointment for tomorrow at the Chevy Chase MedStar facility to have checked out that lump / infected area at the base of my neck.

My understanding is that you don't need a fucking "TESTS POSITIVE!!" Covid test for that -- in fact, that is done separately upon scheduling. This might be different than how it is done at the nearby Lafayette Center MedStar facility where the person who is notionally my regular doctor sees patients.


About the condition of that lump, it has gone down considerably but it looks horrible -- or red, the skin broken, pus having oozed out -- and there is still something of an infection under it.

I continue to take the leftover Amoxicillin, which if it was indeed a bacterial infection in the lymphatic system as I suspect, probably was a real (life) saver for me.


Changing subjects, had intended an entry last night, but I fell asleep kind of early after going to Bangkok Joe's in Georgetown and walking home. I didn't even make it half way through the MeTV Super Sci-Fi Saturday Night line up from the Svengoolie-hosted monster movie (Mighty Joe Young) and beyond, just ending at Buck Rogers in the 25th Century (it was the pilot episode of the original series).

OK, that's all for now. I will try to post an entry tonight.

--Regulus

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