| Observation Date |
Observation Time |
Precipitation |
Snowfall |
Snowfall SWE |
Snow Depth |
Snow SWE |
Notes |
| 10/1/2011 |
7:00 AM |
T |
0.0 |
M |
0.0 |
M |
On 9/30: Sprinkle ~1345LT ... On 10/1: -RA B~730LT. |
| 10/2/2011 |
7:00 AM |
1.06 |
0.0 |
M |
0.0 |
M |
|
| 10/3/2011 |
7:00 AM |
0.03 |
0.0 |
M |
0.0 |
M |
|
| 10/4/2011 |
7:00 AM |
0.06 |
0.0 |
M |
0.0 |
M |
|
| 10/12/2011 |
7:00 AM |
0.02 |
0.0 |
M |
0.0 |
M |
On 11th: Sprinkle ~1700LT; On 12th: OCNL --RA/-RA ~445LT-OBS |
| 10/13/2011 |
7:00 AM |
2.02 |
0.0 |
M |
0.0 |
M |
0.32" during OBS-100LT: OCNL -RA/--RA, mainly late afternoon on the 12th ... 1.70" during 100LT-OBS: OCNL --RA/-RA before TSHRA/+TSHRA 500-630LT. Storm was very slow moving up Falls Road from SSW to NNE, numerous loud, drawn-out thunderclaps during its approach. A couple lightning bolts within 1/10 mile 510-545LT. |
| 10/14/2011 |
7:00 AM |
0.81 |
0.0 |
M |
0.0 |
M |
|
| 10/15/2011 |
7:00 AM |
0.47 |
0.0 |
M |
0.0 |
M |
|
| 10/16/2011 |
7:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 10/19/2011 |
8:00 AM |
0.56 |
0.0 |
M |
0.0 |
M |
|
| 10/20/2011 |
7:00 AM |
0.23 |
0.0 |
M |
0.0 |
M |
|
| 10/25/2011 |
7:00 AM |
T |
0.0 |
M |
0.0 |
M |
|
| 10/27/2011 |
7:00 AM |
0.13 |
0.0 |
M |
0.0 |
M |
|
| 10/29/2011 |
9:00 AM |
0.58 |
0.1 |
M |
T |
M |
On 28th: OCNL -RA/-DZ B~1930LT, soon becoming continuous. ...:... On 29th: 0.12" measured at 100LT. Period of -SN/-RA ~645-710LT drops a thin slushy coating on most non-paved surfaces. -RA 710LT-OBS, but most of slush remains on car tops; slush as a thin film/whitish hue on bricks/grass, respectively. |
| 10/30/2011 |
9:00 AM |
0.62 |
0.5 |
M |
T |
M |
OBS-1230LT: -RA/OCNL RA, with a few wet flakes or pellets mixing in at times 928-955LT. 1230LT-1400LT: -RA/-PE/-SG? mixing with and changing to -SN (wet, small flakes). 1400-1430: -wet SN. 1430-1515LT: -wet SN/wet SN. 1515-1530LT: flakes becoming drier and bigger. 1530-1600LT: -SN/SN. 1600-1620LT: SN/-SN. 1620: Intensity decreasing as flakes drop in size, yet remain dry. 1620-2000LT: -SN, almost -SN/SN at times. 2000-2045LT: -SN quickly tapering to only a few flakes and lingering before finally ending. ...:... Measurable accumulation only on car tops and wood; grassy surfaces away from pavements saw a wet "dusting". ...:... Many temperatures up and down: Max of 36 ~1200LT from lull in -RA; Min of ~32.6 ~1530-1600LT; Max of 34 ~2000-2030LT; Min of 31 (first freeze of year) at about dawn before OBS. |
| 11/1/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 11/4/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 11/5/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 11/8/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 11/9/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 11/10/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 11/11/2011 |
7:00 AM |
0.11 |
0.0 |
M |
0.0 |
M |
|
| 11/12/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 11/13/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 11/14/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 11/15/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 11/16/2011 |
7:00 AM |
0.20 |
0.0 |
M |
0.0 |
M |
On 15th (0.04"): OCNL sprinkles 1200-1230LT, then only a few drops 1230-1630LT, OCNL --RA/sprinkles 1630-2330LT, steady -RA >2330LT. ...:... On 16th (0.16"): OCNL -RA, although briefly -RA/RA ~1237-1245LT. |
| 11/17/2011 |
7:00 AM |
0.39 |
0.0 |
M |
0.0 |
M |
On 16th: Essentially continuous -RA, except -RA/RA ~1040-1050LT, E~2330LT. (0.37")
On 17th: OCNL -RA ~400-700LT. (0.02") |
| 11/18/2011 |
8:00 AM |
0.00 |
0.0 |
M |
0.0 |
M |
On 17th: Possible stray drop or flake during morning, but likely not. |
| 11/19/2011 |
7:00 AM |
0.00 |
0.0 |
M |
0.0 |
M |
|
| 11/20/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 11/21/2011 |
7:00 AM |
0.17 |
0.0 |
M |
0.0 |
M |
On 20th: Sprinkles at 1005-1010LT and 1245-1250LT...few drops 1402-1420LT...DZ-/RA-- 1610-1815LT...generally continuous RA-/RA-- 2115-2345LT. (totaling 0.09")...:...On 21st: additional RA-/OCNL RA? ~1230-230LT ... possible -DZ ~230LT-OBS as dense fog formed. |
| 11/22/2011 |
7:00 AM |
0.19 |
0.0 |
M |
0.0 |
M |
On 21st: Dense fog <900LT. Some stray -DZ possible OBS-1400LT, but mainly just clouds...then -DZ returns with -FG ~1400LT, before -RA/OCNL -DZ ~1600LT-MDNT (0.09")...:...On 22nd: OCNL -DZ/-RA MDNT-OBS, but mainly <500LT (0.10"). -FG around OBS. |
| 11/23/2011 |
7:00 AM |
1.28 |
0.0 |
M |
0.0 |
M |
On 22nd: Generally continuous -RA, except periods of RA ~1230-100LT & 1550-1615LT. Then -DZ/-RA, possibly tapering to only -BR at times 2100LT-OBS (0.90")...:...On 23rd: -RA/RA MDNT-~430LT (0.38"). |
| 11/24/2011 |
7:00 AM |
T |
0.0 |
M |
0.0 |
M |
On 23rd: Sprinkle ~900LT ... -SHRA 1540-1600LT |
| 11/25/2011 |
7:00 AM |
0.00 |
0.0 |
M |
0.0 |
M |
|
| 11/28/2011 |
7:00 AM |
T |
0.0 |
M |
0.0 |
M |
On 27th: Few drops seen around 2220-2225LT ...:... On 28th: possible, but unlikely drop/sprinkle in early AM. |
| 11/29/2011 |
7:00 AM |
0.08 |
0.0 |
M |
0.0 |
M |
On 29th: Brief -SHRA/SHRA ~0050LT. Then likely additional -RA/(RA?) ~230-315LT. |
| 11/30/2011 |
7:00 AM |
0.54 |
0.0 |
M |
0.0 |
M |
On 29th: Generally continuous -RA ~900-1500LT, but RA at times ~1000-1400LT. |
| 12/1/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/3/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/4/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/6/2011 |
8:00 AM |
0.08 |
0.0 |
M |
0.0 |
M |
On 5th: Stray drop likely fell ~1430-1440LT. ...:... On 6th: -DZ/sprinkles likely began ~100LT, eventually becoming -RA overnight. Only a few drops falling at OBS. |
| 12/7/2011 |
7:45 AM |
0.74 |
0.0 |
M |
0.0 |
M |
On 6th: OCNL -RA late AM-~2030LT (0.16") ...:... On 7th: -RA ~300-500LT, then RA/-RA 500LT-OBS (0.58"). At all other times OCNL -DZ or few drops may have fallen. |
| 12/8/2011 |
7:45 AM |
1.76 |
T |
M |
0.0 |
M |
Most 24-HR (MDNT-MDNT) December precipitation since 12/18/1977 (~3.15").
Snow mixing with rain after 2115LT, ending quickly 2305LT. Skies mostly clear before midnight. |
| 12/9/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/10/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/11/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/12/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/14/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/15/2011 |
7:00 AM |
T |
0.0 |
M |
0.0 |
M |
On 14th: Few drops ~1450LT |
| 12/16/2011 |
7:00 AM |
0.03 |
0.0 |
M |
0.0 |
M |
On 15th: Sprinkle @ 1315LT before nearly steady -RA/--RA ~1400-1610LT |
| 12/17/2011 |
7:00 AM |
T |
T |
M |
0.0 |
M |
On 16th: Likely a few ice pellets ~2000LT. |
| 12/18/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/19/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/20/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/21/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/22/2011 |
7:00 AM |
0.10 |
0.0 |
M |
0.0 |
M |
On 21st: -RA late AM-afternoon |
| 12/23/2011 |
7:00 AM |
1.28 |
0.0 |
M |
0.0 |
M |
On 22nd: RA/-RA B~1910LT, only -RA at 1159LT. ...:... On 23rd: -RA/--RA E soon after midnight, but then squall line brings +SH RA/SH RA 255-300LT. |
| 12/24/2011 |
7:00 AM |
0.02 |
0.0 |
M |
0.0 |
M |
-RA ~400-600LT |
| 12/25/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/26/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/27/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/28/2011 |
7:00 AM |
0.63 |
0.0 |
M |
0.0 |
M |
On 27th: -RA/OCNL -RA/RA 910-1615LT |
| 12/29/2011 |
12:00 AM |
0.00 |
0.0 |
M |
M |
M |
|
| 12/30/2011 |
7:00 AM |
0.01 |
T |
M |
0.0 |
M |
On 29th: --SN ~1310-1450LT. Liquid was just above 0.005", frozen just shy of 0.05", so SLR ~8:1 to 9:1. |
| 12/31/2011 |
7:00 AM |
0.01 |
0.0 |
M |
0.0 |
M |
-SH RA ~555-610LT. Between 0.005 and 0.01". |
| 1/3/2012 |
7:00 AM |
T |
T |
M |
0.0 |
M |
On 2nd: Few flakes/light flurry noticed 1325-1330LT, although other such instances were certainly possible a few hours before and after this time. |
| 1/12/2012 |
7:00 AM |
1.50 |
0.0 |
M |
0.0 |
M |
On 11th: Sprinkles B 1123LT, soon becoming generally steady -RA (0.58") ...:... On 12th: RA/-RA E~450LT. (0.92"). |
| 1/13/2012 |
7:00 AM |
M |
T |
M |
0.0 |
M |
|
| 1/21/2012 |
7:00 AM |
0.24 |
1.3 |
M |
1.0 |
M |
On 20th: -SN/(-SG?) B~2200LT. -GS (Snow pellets) likely mixing in >2300LT. (0.07", 0.7", SLR ~9:1) ...:... On 21st: -SN/-GS mixing with -PL and possibly -FZRA before becoming all -FZRA/-FZDZ ~100-300LT. -FZDZ/-FZRA continuing thru OBS. (0.17", ~0.6" Frozen, ~0.08-0.10" ice) |
| 1/22/2012 |
7:00 AM |
T |
0.0 |
M |
0.5 |
M |
On 21st: OCNL -FZDZ/-FZRA until ~1100LT. During day, superficial freezing rain seeped ~0.5-1.0" down into snow/sleet base. Surfaces that saw less than 1" of snow slowly turned from white to clear under glaze. ~1" of snow/ice on ground at 0000LT. |
| 1/23/2012 |
7:00 AM |
T |
T |
M |
M |
M |
On 22nd: A few flakes 1125-1150LT ... then very fine mist/--FZDZ ~1700LT-2330LT. ...:... On 23rd: More mist/--FZDZ overnight as light fog develops and becomes moderate by dawn. |
| 2/29/2012 |
11:40 AM |
1.12 |
M |
M |
M |
M |
|
| 4/2/2012 |
7:00 AM |
0.16 |
0.0 |
M |
0.0 |
M |
Few drops 1914-1916LT & 1946-1950LT...then -RA B~2145LT, tapering to -SH RA's, E <300LT among windy predawn. |
| 4/12/2012 |
7:00 AM |
T |
T |
M |
0.0 |
M |
Few rain drops & -PE 1230LT...sprinkle/--PE 1320-1330LT...sprinkles 1430-1435 & 1750-1755LT...few more likely in evening. |
| 4/15/2012 |
7:00 AM |
T |
0.0 |
M |
0.0 |
M |
Sprinkle ~0055-0105LT |
| 4/19/2012 |
7:00 AM |
0.30 |
0.0 |
M |
0.0 |
M |
Sprinkles becoming --RA/-RA 708-1140LT...mostly continuous -RA >1140LT...then OCNL -DZ/-RA w/light fog thru late PM-early evening. |
| 5/28/2012 |
7:00 AM |
0.53 |
0.0 |
M |
0.0 |
M |
TSHRA/-TSHRA 2045-2130LT (0.52"), then fairly continuous -RA/--RA ~2135-2300LT (0.01"). |
| 6/18/2012 |
8:00 AM |
0.27 |
0.0 |
M |
0.0 |
M |
-SH RA/SH RA 430-515LT before tapering to few drops thru ~615LT, then OCNL -RA thru OBS. |
| 6/30/2012 |
7:00 AM |
1.25 |
0.0 |
M |
0.0 |
M |
Severe Winds chop over or uproot several trees, mainly pine, in immediate neighborhood. Wootton Parkway impassable between Darnestown Road and Hurley Avenue. Unprecedented wind damage since our arrival in Rockville in 1984, only possible exception being 17-18 Sep 2004 (Hurricane Ivan Remnants). |
| 7/14/2012 |
7:00 AM |
2.05 |
0.0 |
M |
0.0 |
M |
Overnight showers B~before 515LT...culminating in +SHRA/++SHRA 615-700LT, with lone clap of thunder at ~645LT. Greatest 24-HR rainfall in 7 months (12/7/2011), greatest 1-HR rainfall in 11 months (8/14/2011). |
| 7/20/2012 |
7:00 AM |
2.13 |
0.0 |
M |
0.0 |
M |
-TSHRA 920-937LT...+TSHRA 937-950LT (~1.50")...-TSHRA 950-1130LT (1.70 storm total). Then a small, locally impressive SHRA B~0000LT (0.42" at 100LT, additional 0.01" at Obs). |
| 7/21/2012 |
7:00 AM |
0.91 |
M |
M |
M |
M |
|
| 8/12/2012 |
7:00 AM |
0.81 |
M |
M |
M |
M |
|