Monday was quite a day. Starting out calm and peaceful with clouds and fog, and very stable temperatures in the upper 50s to around 60°, the afternoon really got going as temps finally started to warm up to around the 80° mark. A mesocale convective complex came roaring out of the Midwest and created heavy thunderstorms, high winds, vivid lightning and plenty of thunder. Depending on where you were in the area, the heavy weather took a variety of forms that are normally associated with severe thunderstorms. An isolated funnel cloud prompted a tornado warning for nearby areas of VA that actually extended into parts of my county for a time in the later afternoon. Severe thunderstorm warnings were in place at one time over the entire metro area. I had my storm with heavy rain (0.59″) and high winds at most times between 1830 to 1930, though lightning and thunder/occasional showers have persisted up to the current time. The Monday maximum temperature reached 80.3° @ 1604, while the Monday minimum temperature was 59.5° @ 0407. The dew point temperatures rose from Sunday, ranging from a low of 59° @ 0000 up to a high of a muggy 71° @ 1842 during the thunderstorm. The barometric pressure lowered a bit from Sunday, reaching the highest value of the day of 30.05″ @ 0010 down to a low of 29.90″ @ 2027. The relative humidity remained high, ranging from a high of 98% at 0400 down to a low of 70% at 1605, just ahead of the severe weather outbreak.

Remember now you can get the VP2 data on Weatherlink. You can access the data through http://www.weatherlink.com/user/walrusman444

I am posting daily to weather underground. My ID is KMDROCKV200 and my station is called “Gardens of Traville.” Data is online, normally just about in real-time. The web address for my data on weather underground is: https://www.wunderground.com/personal-weather-station/dashboard?ID=KMDrockv200#history/ I contribute daily to cocorahs as Rockville 2.8 WNW, Station ID MD-MG-115 on https://www.cocorahs.org/ Please remember that Weather Underground does not report snow data, and reflects what is recorded automatically through the tipping bucket VP2 gauge. I use the data I post to cocorahs as my “official” precipitation total each day.

Monday was quite a day as has already been partially described. One aspect I didn’t mention is a further explanation of the mesoscale convective complex (MCC). It is a large clustered area of concentrated heavy thunderstorm activity that can move quite rapidly along. At times derechos have been known to form within these complexes. Derechos are fast moving storms that have particularly high winds, which in today’s case maxed out in the 70s sporadically. The official word from NWS has not come out as yet as to whether or not we had a derecho. Additionally, derechos are supposed to hold together for hundreds of miles, and I don’t know if that was the case with today’s case.  But we sure had floods, damaging winds, lightning strikes, and power outages to name just a few adverse activity from today’s storms. As I write this at 0400 there still is a rumble of thunder plus wet streets. Tuesday should be mostly cloudy and hot, with highs in the lower 90s and lows in the mid 60s, with a 100 POP for thunderstorms. Wednesday through Saturday should be mostly cloudy and cooler (but plenty muggy) with highs in the upper 60s to mid 70s and lows in the low 60s, with an 80-100% chance for rain or thunderstorms each day. We continue to be in a persistent battle zone (along a stationary frontal boundary) fluctuating from mild to very warm temps and numerous threats of rain or thunderstorms during the coming week.

On the Channel 4 radar at 0510 continues to show persistent shower and thunderstorm activity over the Metro area and a good part of the 4 state Mid-Atlantic region.

As of 0510, the data from the VP2 (coming from the ground radiation shield about 4 feet off the ground just under and out from the balcony) and the Lakewood WX Bug station are as follows:

Cloudy, stormy, cool – looks like another cloudy day ahead……

Station Relative Location Temp  RH   DP     BP       Wind High/Low temp on Monday
VP2             Ground        64.2° 95% 63° 29.95″F    NA     80.3°/59.5°

The total precipitation in the cocorahs gauge was 0.59″ through midnight Monday. The VP2 tipping bucket rain gauge under my balcony recorded 0.00″ through midnight Monday as it continues to be clogged.

Monday’s precipitation was 0.59″
May precipitation is now 1.10″
Year-to-date precipitation total is 12.84″

WX Bug Lakewood 4500 ft, 64° 98% 63° 30.00″F WSW 4 G WNW 10
                           140° from station                           83°/59°

The Lakewood rain gauge reported only 0.02″ of precipitation on Monday. May is now showing 1.41″ for the month and the 2018 year-to-date (YTD) amount is 16.22″. I still believe at times the great disparity between the Lakewood WX Bug station precipitation amount total for the month and year and my cocorahs gauge based data is that the Lakewood precip values are estimated/adjusted from radar.

At 2400 obs Monday night the temperature from the VP2 was 65.0° RH 96% BP 30.01″R DP 63.8°
Cloudy, cool, damp, stormy at 2400 Monday

Good morning from the cloudy, damp, still stormy home of the soggy walrus on this Tuesday morning.