JANUARY 2020 MONTHLY SUMMARY ROCKVILLE 2.8 WNW MARYLAND by Kevin Shaw, Observer

January 2020 was warmer and a bit wetter than normal. My maximum temperature average (46.9°) was 5.6° above normal but my minimum temperature average (32.8°) was much more significantly above normal (+ 8.3°), resulting in the mean temperature average of 39.9° to be 6.9° above normal. My total precipitation of 3.17″ was 0.26” above the normal January value for my station of 2.91”. There were 10 days with measurable precipitation, almost all of which occurred between the 3rd and 25th. All 1.6 “of the monthly snow occurred on the 7th-8th period (1.6” on the 7th and a trace on the 8th)

There was one small, moderately cold spell during the month, but there was only one really cold day when the max temp stayed at or below freezing (32.0° on the 20th). The low of 19.5° the next morning on the 20th was the coldest reading of the month. This moderate cold spell fell between 17th and 21st. One really notable high temperature period occurred during the
month, with the two highest max temperatures of the month occurred on the 11th (69.6°) and the 12th (66.3°).

The monthly maximum daily precipitation of 1.52″ on the 25th was at the end of measurable precipitation for the month. Another significant occurrence took place earlier in the month. The highest (30.72” on the 9th) pressure reading of the month was preceded by the lowest pressure of the month 5 days earlier on the 4th when 29.49” was recorded. 0.60” of rain fell at this time (3rd and 4th) which was the 2nd wettest precipitation event of February. The only other pattern involved with these pressure extremes is that the warmest period of the month followed the highest pressure of the month on the 9th, with 69.6°
reached on the 11th and 66.3° on the 12th. The pressures fell off some during this warm spell but not very much.

The highest dew point temperature reached during the month was 63° on the 11th and 12th during the aforementioned warm spell. With the colder temperatures dew points continued much lower than previous months, and never high enough to produce any discomfort. The lowest dew point temperature value was reached on the 20th with a 9° reading, on the coldest max day of the month.

January had 3 cloudy days, 12 partly cloudy days, and 16 clear/sunny days, not based on my own personal daily observations for the most part but rather the official F6 sky cover records for Dulles and BWI airports. There were 780 heating degree days and no cooling degree days during the month. There were 9 foggy days, 12 windy days, and 2 days with snow. The peak wind gust noted from across the street at the USG gauge during January was 46 MPH from the NW on the 19th during the strongest cold front of the month.

My maximum temperature frequencies included 2 days between 60° and 69°, 9 days between 50° and 59°, 16 days between 40° and 49°,d 4 days below 40°. On the minimum temperature frequency side of things, there were 11 days below 30°, 14 days between 30° and 39°, 5 days between 40° and 49°, and 1 day of 50° or above. The coldest daily max temperature day was 32.0° on the 20th while the warmest daily min temp day of 51.3° was reached on the 11th.

The diurnal range daily monthly average was only 14.1° (- 2.7°). Our greatest daily range of temperature was 25.4° on the 22nd (45.3°-19.9°). Once again we only had a total of 4 days with daily ranges above 20°. Our lowest range of temperature was 3.9° (46.6°-42.7°) on the 2nd. There were only 4 days with diurnal temperature ranges of less than 10° during the month, much less than the 12 recorded in December.

January 2020 was a bit wet and another mild month as we start on a new year and decade. I barely got below the 20° mark, reaching only 19.5° on the coldest day of the month. My meager seasonal snowfall of 3.0° was quite depressing and probably about 20-25% of normal. There still has been no real ice formation on local ponds. My new Davis Vantage Vue console has yet to be made operational, but I have been using Marty’s spare VP2 console to do the trick so far. Marty has resolved a possible
glitch in the Vue console, and we are waiting to get together to set that up, along with my new Dell computer, which needs to get my Thunderbird email program to be loaded onto. We still haven’t found the time to do all this and much more.

JANUARY 2020 – ROCKVILLE 2.8 WNW MARYLAND – SUMMARY STATISTICS

Average high temperature 46.9° (+ 5.6°)
Average low temperature  32.8° (+ 8.3°)
Mean temperature            39.9° (+6.9°)

Precipitation                                  3.17″ (+0.26“)
Greatest daily amount (date)           1.52″ (25)
Greatest storm total (dates)             1.53” (24-25)
2020 year-to-date precipitation total 3.17″ (+0.26”)

Total monthly snowfall                      1.6” (7-8)
Total seasonal snowfall                     3.0”

High temperature for the month (date)  69.6° (11)
Low temperature for the month (date)   19.5° (21)

Highest barometric pressure (date)    30.72” (9)
Lowest barometric pressure (date)     29.49” (4)

Peak wind gust (date/direction): 46 (19/NW)
(USG data across the street)

Heating degree days for the month:    780
Cooling degree days for the month:       0

Greatest diurnal range (date):     25.4° (22)
Least diurnal range (date):           3.9° (14)

Number of days:

Fog 9
Windy 12 (PWG => 30 MPH)
Snow 2
Sleet/Glaze 0
Cloudy 16
Partly Cloudy 12
Sunny/Clear 3
Max temp = 60° 2
Min temp <= 32° 16
Max temp <= 32° 1
Precip = 0.01” 10

PDF File of my January 2020 excel data spreadsheet: 

2020-01 Rockville 2.8 WNW