Tuesday, May 16, 2017

KDMH: The Inner Harbor Little ASOS Station That Could, Hon, Plus Background Info on the Baltimore & Washington, D.C., Weather Stations

The Maryland Science Center NWS weather station behind its protective fence, Inner Harbor, Baltimore, Md., 4:54PM May 13, 2017.


(Chester: If I've made any factual errors in here, please let me know.)

On my visit this past Saturday to Baltimore with my mom for a pre-Mother's Day lunch at the Rusty Scupper, I took the opportunity before we left to walk the short distance to the Maryland Science Center and take a picture of the NWS weather station located there.

Exterior of the Maryland Science Center (online image).


The Maryland Science Center at the Inner Harbor in Baltimore, Md., is unusual for weather enthusiasts in that it has its very own ASOS weather observing station.

Known by its four-letter identifier KDMH, it is one of four such ASOS stations in the Baltimore/Washington region.

Maryland Science Center and adjoining ASOS station at Baltimore Inner Harbor location, noted.

This is a picture that I found online years ago -- and subsequently marked as shown to note what's what and featured it in this long-ago July 2011 entry during an intense heatwave. In that entry, I should have denoted it as "KDMH" instead of "DMH" and called it an "ASOS" station (see below).


The other three ASOS stations in the immediate Baltimore/Washington area are at the three main regional airports, namely, Ronald Reagan Washington National Airport (KDCA), Baltimore/Washington International Thurgood Marshall Airport (KBWI), and Washington Dulles International Airport (KIAD).

These are the four for which the Baltimore/Washington NWS in Sterling, Va., provides daily weather ("climate") summaries. (The NWS uses the term "climate summaries" since the information forms the statistical basis of the regional climate.)

The KDMH ASOS, Inner Harbor, Baltimore, Md., 4:56PM May 13, 2017.


ASOS is an abbreviation for and acronym representing the Automated Surface Observing System, which is "a joint effort of the National Weather Service (NWS), the Federal Aviation Administration (FAA), and the Department of Defense (DoD) that serves as the primary surface weather observing network for the United States. ASOS is designed to support weather forecast activities and aviation operations and, at the same time, support the needs of the meteorological, hydrological, and climatological research communities." -- Source here (and paraphrased slightly).

The rain gauge at the KDHM ASOS, 4:55PM May 13, 2017.

There are over 900 ASOS stations in operation presently, many of which are sited at civilian regional and international airports.

The ASOS network is distinct from the much larger NWS Cooperative Observer Program (COOP) in which over 10,000 volunteers around the U.S. record the daily high and low temperatures, 24-hour precipitation, and snowfall in a nationwide network.

The ASOS network is also distinct from the CoCoRaHS network. CoCoRaHS is an abbreviation signifiying the Community Collaborative Rain, Hail and Snow Network. You can read more about the CoCoRaHS network here.

Oh, and there is also the Automated Weather Observing System (AWOS) and the Automated Weather Sensor System (AWSS) networks, but these are run primarily or exclusively by FAA.

Temperature sensor, KDMH ASOS, Inner Harbor, Baltimore, Md., 4:55PM May 13, 2017.


Other ASOS stations in the Sterling county warning area (CWA) are in Charlottesville (Charlottesville Albemarle Airport), Va.; Martinsburg (Eastern WV Regional Airport/Shepherd Field), W.Va.; and Hagerstown, (Washington County Regional Airport), Md. There are AWOS stations at smaller regional airports such as Martin State Airport and Montgomery County Airpark.

Maps of Maryland and Virginia FAA ASOS and AWOS stations are available here and here, respectively.

The current ASOS network dates back to 1991 and was completed (with the exception of new stations that are added) in 2004.

Maryland ASOS and AWOS station list; KDMH is a non-FAA weather station so it isn't on this list.


As alluded to above, the KDMH ASOS station is unusual in that it is located in such a public space. ASOS stations are normally at sprawling and highly restricted outdoor stretches of airports beyond the runways and tarmac. In this way, KDMH is not an FAA ASOS. Another example of a non-FAA ASOS is in Central Park in New York City.

New York City ASOS station located next to Belvedere Castle folly in Central Park (KNYC); the wind data is recorded atop the castle.


The ASOS station at the Maryland Science Center was put into commission on April 29, 1998. The NWS moved it there from the nearby U.S. Custom House location owing to the chronically badly overheated situation at the latter spot.

U.S. Custom House, Baltimore, Md.

The Custom House station was decommissioned at some point after the Maryland Science Center one was commissioned.


That (rooftop?) weather station had been there back to 1908 shortly after the building was completed. As explained here, prior to that, it was located at Johns Hopkins University back to 1871 when the U.S. Government began official weather observations via the Signal Service, although the Weather Bureau took over the operations in June 1891.

Aerial view of the KBWI ASOS.


A separate airport station opened Feb. 16, 1930 at the old Logan Field, moving to Baltimore Municipal Airport in 1945 and then-Friendship International (now BWI) Airport in July 1950 upon opening of the airport and where operations were combined with the city office.

U.S. Weather Bureau Headquarters, 2400 M Street NW, Washington, D.C., circa 1910.


In the case of Washington, D.C., its official weather station was moved from its previous location at the U.S. Weather Bureau Headquarters located at 2400 M Street NW in 1945 to its current, highly problematic spot at National Airport (KDCA).

This was a few years after that airport opened -- and, as with Baltimore, the story is a bit more complicated in that there was another weather station at Hoover Field and the subsequent combined Washington-Hoover Airport.

Aerial view of the KDCA ASOS.

Snowfall -- when it occurs -- is (mis-)measured elsewhere on the airport grounds.


And just FYI, snow observations began later -- Dec. 1883 in Baltimore and January 1888 in D.C. Dew point records came even later -- starting in or around 1936.

The Dulles Int'l Airport (KIAD) station has been there since January 1963 not long after the airport opened.

North-looking ground view of the KBWI ASOS.


The move from the Custom House to BWI Airport in a much less urban setting resulted in the climate of Baltimore having the ability to record colder winter lows (when we have winter cold snaps, that is) and more snow in snowstorms. It can also get really hot on the hottest of summer days -- such as 106F on July 22, 2011, second hottest ever in Baltimore.

Panoramic view of National Airport and in the distance, Washington, D.C.


Conversely, the move from 24th and M Street NW to National Airport on its tidal Potomac location has resulted in the near disappearance of record low temps* and, conversely, the inability to get to sustain really hot temps on the hottest of summer days. Record high minima, though, are easy to set there.

*The fact that the overall climate has warmed has also, obviously, contributed to this effect.

Ratio of record warmth to record cold instances, Washington, D.C., 1870s - 2010s.


Oh, and KDCA snowfall totals have been miserably pathetic ever since (although that topic also gets into the weird personality issue as well for the past 32 years involving one individual, but I'm not getting into that now).

Another picture of the KDMH ASOS, Baltimore, Md., 4:56PM May 13, 2017.


In the case of KDMH, since it has been in operation only since 1998, and since the 30-year NWS "normal" period is considered 30 years, the station won't have a full climate data set until 2028.

Furthermore, since the NWS updates the 30-year averages only every 10 years -- with the current 30-year average the period 1981 - 2010 and the next update to the 1991 - 2020 period due in 2021, KDMH won't have a base period until the following update to the 2001 - 2030 period due in 2031 or 14 years from now.**

**This assumes it and the NWS still exist in their present form, itself contingent on the current, ongoing, GOP-enabled Trumpocalypse not haven't blown up everything).

Screenshot of Sterling (LWX) Climate Information Page.


The Sterling climate webpage is available here. Note there are seven stations in it: KDCA, KBWI, KDMH, KIAD, KCHO, KHGR, and KMRB.

The KDMH hourly observations are available at: http://w1.weather.gov/data/obhistory/KDMH.html

For whatever reason, this page does not report a number of variables -- only temperature, air pressure, and precipitation. KDMH also does not record snowfall (there is no snowboard and person with a snow ruler to make measurements).

The other six ASOS station observations are available at:


And with that, I think I shall end this entry. My next planned posting is late tomorrow night after the gym.


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