George BM

...FLASH FLOOD WATCH IN EFFECT FROM THIS EVENING THROUGH SUNDAY MORNING... The National Weather Service in Sterling Virginia has issued a * Flash Flood Watch for portions of Maryland, The District of Columbia, Virginia, and West Virginia, including the following areas, in Maryland, Anne Arundel, Carroll, Central and Southeast Howard, Central and Southeast Montgomery, Charles, Frederick MD, Northern Baltimore, Northwest Harford, Northwest Howard, Northwest Montgomery, Prince Georges, Southeast Harford, and Southern Baltimore. The District of Columbia. In Virginia, Arlington/Falls Church/Alexandria, Clarke, Culpeper, Eastern Loudoun, Fairfax, Frederick VA, Greene, Madison, Northern Fauquier, Northern Virginia Blue Ridge, Page, Prince William/Manassas/Manassas Park, Rappahannock, Rockingham, Shenandoah, Southern Fauquier, Stafford, Warren, and Western Loudoun. In West Virginia, Eastern Pendleton, Hardy, Jefferson, and Western Pendleton. * From this evening through Sunday morning * Widespread showers will develop this evening along with possible thunderstorms and locally heavy rainfall is expected. Average rainfall amounts will be between 1 and 3 inches with locally higher amounts around 4 inches possible. * Heavy rainfall in short periods of time may cause creeks and streams to rapidly rise out of their banks along with the potential for flash flooding in urban areas. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Flash Flood Watch means that conditions may develop that lead to flash flooding. Flash flooding is a very dangerous situation. You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued. && $$

...FLASH FLOOD WATCH IN EFFECT FROM THIS EVENING THROUGH SUNDAY MORNING... The National Weather Service in Sterling Virginia has issued a * Flash Flood Watch for portions of Maryland, The District of Columbia, Virginia, and West Virginia, including the following areas, in Maryland, Anne Arundel, Carroll, Central and Southeast Howard, Central and Southeast Montgomery, Charles, Frederick MD, Northern Baltimore, Northwest Harford, Northwest Howard, Northwest Montgomery, Prince Georges, Southeast Harford, and Southern Baltimore. The District of Columbia. In Virginia, Arlington/Falls Church/Alexandria, Clarke, Culpeper, Eastern Loudoun, Fairfax, Frederick VA, Greene, Madison, Northern Fauquier, Northern Virginia Blue Ridge, Page, Prince William/Manassas/Manassas Park, Rappahannock, Rockingham, Shenandoah, Southern Fauquier, Stafford, Warren, and Western Loudoun. In West Virginia, Eastern Pendleton, Hardy, Jefferson, and Western Pendleton. * From this evening through Sunday morning * Widespread showers will develop this evening along with possible thunderstorms and locally heavy rainfall is expected. Average rainfall amounts will be between 1 and 3 inches with locally higher amounts around 4 inches possible. * Heavy rainfall in short periods of time may cause creeks and streams to rapidly rise out of their banks along with the potential for flash flooding in urban areas. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Flash Flood Watch means that conditions may develop that lead to flash flooding. Flash flooding is a very dangerous situation. You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued. && $$

Severe Weather Disco May 3 2019 4:00AM EDT Today will potentially be the most dangerous severe weather day experienced in the area in decades. The SPC in Norman, OK has issued a high risk for severe weather for a high likelihood of widespread destructive winds with this afternoon and evenings round of storms. Tornadoes will also be likely with both the morning and afternoon rounds of storms with several strong to violent and long-track tornadoes likely, especially with the afternoon/evening round. Very large hail will also be a threat with the afternoon/evening round of storms. On top of all of this there will be a significant flash flood threat, mainly during the morning hours, as storms train over the same areas with torrential rain. Please use extreme caution if you must travel today. Rain is currently moving into the western parts of the CWA with some embedded supercells, some already tornadic. Low-level shear will increase as we go through the morning and bands of heavy rain and embedded supercells will continue to quickly move through our region from SSW to NNE. Despite no sunshine, dewpoints rising into the middle 70sF will lead to 1100-1600 J/kg mucape rooted near the surface. With effective SRH in excess of 400 m2/s2, EBWD of 65+ kts and a strong low-level jet (70+kts winds at 1km) several tornadoes appear likely with even a couple strong, long-track tornadoes possible. There will also be a fairly significant damaging wind threat with any organized supercells and bowing line segments. The timing for this round of storms will be between 4am and 10am in the western suburbs. 6am and 12pm in the immediate Washington metropolitan region, and 8am and 2pm along the Chesapeake Bay. The other large threat with this morning round of severe weather will be for flash flooding as PW values will reach the 2.2-2.4 inch range allowing for any storms to contain very heavy rainfall rates. Many of these storms may train over the same areas leading to potentially significant flash flooding wherever this occurs. Rainfall totals through the early afternoon across the region will range from 2 to 5 inches with locally higher amounts where storms train over the same areas. For this a Flash Flood Watch is in effect for the entire forecasting area through the evening. The pressure gradient will also become very tight and with a powerful low-level jet overhead wind gusts around 40kts seem to be a good bet even without any aid from convection. Thus, a Wind Advisory is in effect through the morning hours. After this round of rain and storms move out there will be lull as a powerful mid-level jet associated with a very fast moving and powerful shortwave trough will blast into the region promoting ample sunshine through the afternoon allowing temperatures to rise into the middle 80’s. The pressure gradient will increase through the afternoon ahead of the shortwave. With lower-level wind-fields becoming very strong (Mean surface to 850mb winds of 50-55 kts) with increased low-level mixing, synoptic wind gusts to 50-55kts seem plausible which will lead to tree damage and scattered power outages. As a result, a High Wind Warning has been issued for the entire Metropolitan region through the afternoon. At the same time the very powerful trough and associated cold front will approach from the west. Mid-level temperatures will cool (500mb temps dropping to -15C). With dewpoints in the lower 70sF or so, MLCAPE will rise to a very strongly unstable 3000-4500+ J/kg. With a 120+kt mid-level jet moving over the region effective bulk shear will rise to 100+ kts. This shortwave will provide extreme forcing along the cold front. As a result, an extremely dangerous and fast-moving line of storms will develop along the front west of the mountains and race through our region between 4-5pm in far western areas and 7-8pm along the Chesapeake Bay. With the extreme kinematics in place and increasingly steep low-level lapse rates storm motions could be in excess of 80 kts. That combined with ample effective bulk-shear and effective SRH in excess of 500m2/s2 will allow for LEWPS and embedded supercells capable of producing swaths of life-threatening hurricane-force wind gusts, potentially as high as 90 to 100mph, and several tornadoes, some which may be strong. Supercells will develop ahead of the main line and with them several fast-moving strong to violent and long-track tornadoes appear likely given the impressive low-level shear. With the cooling mid-level temperatures severe hail will also be a threat with very large hail (3”+ in diameter) possible in any supercells. Once the storm threat finally ends everywhere after 8pm a record breaking cold airmass will sweep into the region with temperatures everywhere dropping into the 30’s by dawn. With dangerously high winds still in place (wind gusts of 55-70mph), wind chills will drop into the teens in most spots. Forecaster: George BM

CAD war tomorrow. ETA: 68/58 at IAD at 12:00AM EDT May 1, 2019

One little note. No mesoscale model has the current activity in Eastern Ohio about to move into southwest Pennsylvania. CAPE is modest but still... it might be able to trigger something in the area later even if the current convection dies out. Just a small note. #Notanexpertopinion

It's a very low-key threat and more likely than not won't happen this way but a few mesoscale models try to get some remnant storms into the region tomorrow afternoon before they redevelop into asoutheastward moving storm cluster or two. This, of course, would be the most extreme case though. Just low-key watching it and exactly where the WNW to ESE oriented front sets up.

Mar 1, 2019: 0.5" snow/sleet Mar 8, 2019: 0.6" wet snow Total (so far): 24.0"

I wonder if you'd find any kind of damage if you went to those locations? Might be very minimal but still. *shrugs*

Totally and utterly ANNIHILATED!

I love how some areas west of I-95 that hadn't been under a Tornado Watch since February 24, 2016 have been under 3 Tornado Watches in 12 days.

My Dad's office is close by also in Rockville. He called me about the Tornado Warning.

I don't know. That sounds like quite a bit of fun to me... perfect Jebwalking conditions. Have you taken any epic Jebwalks down there yet?

I'll put you down for 90mph.

What wind speed?

It's time to play Guess the intensity of the Reston area tornado last night. I'm going with an EF-0: 75mph winds Guess away! You have until the NWS comes out with the official rating.

Great time for a power outage that probably has nothing to do with the weather.

I'll say this... so far the clouds are SLIGHTLY thinner than they were on Sunday.

Surprised that we aren't at least in some tornado risk atm. I would think that changes later though.

Shoot that was last hour wasn't it. I forgot about it.

BWI: 106F DCA: 108F IAD: 107F RIC: 110F SBY: 105F

Poor Yoda banished from sleep... ...It appears KIAD gusted to 42kts (48mph) with the line that just came through.

June 21 2019 Severe Disco 4:12PM EDT Warm front continues to slowly lift through the region to the NNE in a WNW to ESE axis ahead of an impulse of energy approaching from the west. Along and in the vicinity of this warm front surface dewpoints have risen to around 80F w/ temps into the low 90’sF. Surface winds have also backed to ESE in the vicinity of the warm front. Any remaining CIN is just about gone and a few storm cells are starting to pop up over I-81 near Winchester, VA and Martinsburg, WV. With the extreme instability in place (4500-6500 J/kg mlcape), very strong effective bulk shear (55-65+kts), and strong low-level directional shear (effective SRH 250-450 m2/s2) with low LCLs, these storms and any other storms that pop up may become intense supercells capable of producing tornadoes. Some of these many produce strong and long-track tornadoes as they move east-southeast across the region especially between 5-10pm. These storms will also be capable of dropping very large to giant hail (perhaps 4”+ in diameter) and destructive, perhaps hurricane force winds. Some mesoscale guidance develop a severe MCS behind the initial supercells with the main impulse of energy riding along this frontal boundary. Should a MCS develop a more substantial widespread wind threat with some particularly significant wind gusts may evolve with severe hail and QLCS tornadoes. Bottom line is that this afternoon and evening will be a very dangerous one for severe weather in the Greater Washington Metropolitan area. At this time, tomorrows severe threat seems mainly focused towards the Maryland/Pennsylvania line and the Baltimore region. Forecaster: George BM

Or good tropical .

Northwest of Baltimore Monday afternoon. #Digitalsevere #Soon.