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July Discobs Thread

George BM

By George BM,
in Mid Atlantic

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MN Transplant

MN Transplant

Posted
Posted
25 minutes ago, Eskimo Joe said:

What's impressive with this event is farther north into PA and NY.  It's like every round of precip has rotated back along the Susquehanna River basin...truly a significant hydrologic event up there.

They may have more impact due to terrain, but the epicenter of this event has been Maryland, just west of the Bay.

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yoda

yoda

Posted
Posted
4 minutes ago, Eskimo Joe said:

Okay the last update for the 925 & 850 mb moisture transport finally looks good for DC...direct SE flow and some deep moisture convergence nearby.  Maybe we jackpot the last round here.

I thought it was all headed east and away from us?

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yoda

yoda

Posted
Posted

CWG tweet and story linked below states that a TOR may have touched down at TJ (Thomas Jefferson HS) this morning when Fairfax County was under a TW

https://www.washingtonpost.com/news/capital-weather-gang/wp/2018/07/24/tornado-may-have-touched-down-at-thomas-jefferson-high-school-in-northern-virginia/?noredirect=on&utm_term=.72e6a1ef23aa

At 5:54 a.m., smartphones emitting a high-pitched beep may have rudely awakened residents in east central Fairfax County. The National Weather Service had issued a tornado warning. And preliminary reports from witnesses and emergency-management officials suggest that a small tornado may have touched down around Thomas Jefferson High School, near the border of Alexandria and Annandale.

The National Weather Service received a report from an emergency manager of “damage to a shed, fence line, and athletic field” at the high school, nationally acclaimed for its science and technology magnet program.

Matt Guilfoyle, a spokesman for Fairfax County schools, confirmed minor damage outside the school but none to the main building. “There was some damage to a fence near the football field,” he said. “There was also a container tossed near the football field, and the contents were scattered around the property.” He added that a couple of lamp posts were damaged.

@NWS_BaltWash Storm damage at Thomas Jefferson High School in Alexandria. Several sheds destroyed by trees, fences down, large container tossed. Damage 100-200 feet wide in places. Photos from @Drewshearer444. #vawx pic.twitter.com/nQMrWR4h5u

— NOVA Storm Chasing (@NovaChasing) July 24, 2018

As the possible tornado occurred before the school’s operating hours, “no one was ever in any danger,” Guilfoyle said. “The building has continued to operate normally today.”

A Capital Weather Gang commenter, with screen name bobbyque, also filed a report relaying tornado-like conditions near the high school.  “About 5:45, heavy wind and rain woke me,” the commenter wrote. “The rain was coming in sideways, and the wind and the rain reminded me of hurricanes. I was standing at my rear bedroom windows looking out over a flood management area, and my phone alerted. I could hear deck stuff my from neighbors being tossed around . . . Yikes!”

The very short-lived tornado warning, which included the Lincolnia area of Annandale, Lake Barcroft, Bailey’s Crossroads and Seven Corners, expired after 13 minutes. The Weather Service discontinued the warning at 6:07 a.m. It’s likely that if a tornado touched down, it lasted only minutes and may have occurred before or just as the warning was being disseminated.

In a tweet, the National Weather Service confirmed there was a “small, brief circulation” where it issued the tornado warning. It plans to survey the damage around the high school Tuesday afternoon to evaluate whether a twister actually touched down.

Both the available ground evidence and radar imagery exhibit the fingerprints of a weak, short-lived tornado.

High-resolution radar imagery from the event showed that an intense storm cell, shown below, was moving north across Fairfax County. In addition to very intense rain rates, the cell featured what appeared to be a compact, hooklike structure on its southeastern flank (see arrow on image below). This type of structure often indicates a parent source of rotation, termed a mesocyclone, in the lowest levels of the storm.

XKDZOATWW44HPKW2JS2CCOHBSQ.png
(RadarScope)

Coincident with the hook was a small region of opposing winds called a “velocity couplet” (image below). Green colors represent inbound flow toward the Weather Service radar based in Sterling, Va., while reds are outbound flow. The circled area shows where these opposite flows are adjacent, the likely location of a counterclockwise-spinning mesocyclone (small, intense vortex). This feature would be the parent source of spin that possibly became briefly concentrated into a small, weak tornado.

3XSHYTGINMZKDPDP57OGOWUFL4.png
(RadarScope)

Early-morning tornadoes are rare in the region. They are most common in the afternoon and early evening. However, July is the most active month for tornadoes in the Mid-Atlantic.

The tornado, if it was one, was made possible by a healthy amount of wind shear or turning of the wind with height in the atmosphere. At low levels, winds were blowing from the southeast because of tropical air flow originating from the Bahamas. Higher up, there was a westerly component to the wind because of a front stalled in the vicinity.

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yoda

yoda

Posted
Posted
4 minutes ago, PrinceFrederickWx said:

Yeah I assume the Chesapeake-Potomac hurricane was responsible for the rain totals. Aug. 1955 I’m assuming was Connie and Diane?

Yup... both were within a week of each other.  August 12th was Connie making landfall in S MD and Dianne was August 18th

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mattie g

mattie g

Posted
Posted
31 minutes ago, yoda said:

CWG tweet and story linked below states that a TOR may have touched down at TJ (Thomas Jefferson HS) this morning when Fairfax County was under a TW

https://www.washingtonpost.com/news/capital-weather-gang/wp/2018/07/24/tornado-may-have-touched-down-at-thomas-jefferson-high-school-in-northern-virginia/?noredirect=on&utm_term=.72e6a1ef23aa

 

“There was some damage to a fence near the football field,” he said. “There was also a container tossed near the football field, and the contents were scattered around the property.”

Stay vigilant.

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jconsor

jconsor

Posted
Posted
4 hours ago, mbusada said:

3.67 inches since 8:00 this morning in Lothian, MD. Total since 8:00 am Saturday 16.43”. Areas of our farm are flooded that have never been in the last 30 years. 

Weather Underground station in Lothian backs that up - they have reported 15.99 since Sat:

https://www.wunderground.com/personal-weather-station/dashboard?ID=KMDLOTHI9&cm_ven=localwx_pwsdash#history/s20180716/e20180724/mweek

Another station just to the north reported 15.22":

 https://www.wunderground.com/personal-weather-station/dashboard?ID=KMDHARWO7#history/s20180716/e20180724/mweek

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mattie g

mattie g

Posted
Posted
5 hours ago, mattie g said:

Awful news about the woman who was killed in Burke. Can’t imagine being the husband. :(

Had to reschedule my 10:00 flight because the well is filling up and we now have a plumber on the way to get the new pump installed. Hopefully that’s that and I won’t mind big rain events in the future. :lol:

Got the pump installed at around noon. Thing is a beast. Bring on the rains!

 :yikes:

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yoda

yoda

Posted
Posted

:yikes:

Special Weather Statement
National Weather Service Baltimore MD/Washington DC
547 PM EDT Tue Jul 24 2018

DCZ001-MDZ003>006-011-013-014-016>018-503>508-VAZ025>031-036>040-
050>057-501-502-505>508-WVZ051>053-251000-
District of Columbia-Washington-Frederick MD-Carroll-
Northern Baltimore-Southern Baltimore-Prince Georges-Anne Arundel-
Charles-St. Marys-Calvert-Northwest Montgomery-
Central and Southeast Montgomery-Northwest Howard-
Central and Southeast Howard-Northwest Harford-Southeast Harford-
Augusta-Rockingham-Shenandoah-Frederick VA-Page-Warren-Clarke-
Nelson-Albemarle-Greene-Madison-Rappahannock-Orange-Culpeper-
Prince William/Manassas/Manassas Park-Fairfax-
Arlington/Falls Church/Alexandria-Stafford-Spotsylvania-
King George-Northern Fauquier-Southern Fauquier-Western Loudoun-
Eastern Loudoun-Northern Virginia Blue Ridge-
Central Virginia Blue Ridge-Morgan-Berkeley-Jefferson-
Including the cities of Washington, Hagerstown, Frederick,
Ballenger Creek, Eldersburg, Westminster, Reisterstown,
Cockeysville, Baltimore, Bowie, Suitland-Silver Hill, Clinton,
College Park, Greenbelt, Laurel, Camp Springs, Glen Burnie,
Annapolis, Severn, South Gate, Severna Park, Arnold, Odenton,
St. Charles, Waldorf, Lexington Park, California,
Chesapeake Beach, Huntingtown, Dunkirk, North Beach, Lusby,
Prince Frederick, Germantown, Damascus, Bethesda, Rockville,
Gaithersburg, Silver Spring, Lisbon, Columbia, Ellicott City,
Jarrettsville, Aberdeen, Staunton, Waynesboro, Stuarts Draft,
Harrisonburg, Strasburg, Woodstock, Mount Jackson, New Market,
Winchester, Luray, Shenandoah, Stanley, Front Royal, Berryville,
Lovingston, Charlottesville, Stanardsville, Madison, Orange,
Gordonsville, Culpeper, Dale City, Manassas, Woodbridge,
Lake Ridge, Montclair, Reston, Herndon, Annandale, Centreville,
Chantilly, McLean, Franconia, Arlington, Alexandria, Falmouth,
Fredericksburg, Dahlgren, Warrenton, Turnbull, Purcellville,
Leesburg, Ashburn, Sterling, Big Meadows, Wintergreen, Paw Paw,
Martinsburg, Charles Town, and Shepherdstown
547 PM EDT Tue Jul 24 2018

...TREES TOPPLING DUE TO SATURATED GROUND...

The recent heavy rainfall of the last several days has left the
ground extremely saturated. This is causing many trees to topple
even with little or no wind. If you live in or drive through
wooded areas, remain especially alert for the potential of downed
trees. Consider altering your route or staying in the interior of
the lowest level of your home or office to avoid weakened trees
that may fall tonight and tomorrow.

$$

DHOF
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09-10 analogy

09-10 analogy

Posted
Posted
4 minutes ago, yoda said:

:yikes:


Special Weather Statement
National Weather Service Baltimore MD/Washington DC
547 PM EDT Tue Jul 24 2018

DCZ001-MDZ003>006-011-013-014-016>018-503>508-VAZ025>031-036>040-
050>057-501-502-505>508-WVZ051>053-251000-
District of Columbia-Washington-Frederick MD-Carroll-
Northern Baltimore-Southern Baltimore-Prince Georges-Anne Arundel-
Charles-St. Marys-Calvert-Northwest Montgomery-
Central and Southeast Montgomery-Northwest Howard-
Central and Southeast Howard-Northwest Harford-Southeast Harford-
Augusta-Rockingham-Shenandoah-Frederick VA-Page-Warren-Clarke-
Nelson-Albemarle-Greene-Madison-Rappahannock-Orange-Culpeper-
Prince William/Manassas/Manassas Park-Fairfax-
Arlington/Falls Church/Alexandria-Stafford-Spotsylvania-
King George-Northern Fauquier-Southern Fauquier-Western Loudoun-
Eastern Loudoun-Northern Virginia Blue Ridge-
Central Virginia Blue Ridge-Morgan-Berkeley-Jefferson-
Including the cities of Washington, Hagerstown, Frederick,
Ballenger Creek, Eldersburg, Westminster, Reisterstown,
Cockeysville, Baltimore, Bowie, Suitland-Silver Hill, Clinton,
College Park, Greenbelt, Laurel, Camp Springs, Glen Burnie,
Annapolis, Severn, South Gate, Severna Park, Arnold, Odenton,
St. Charles, Waldorf, Lexington Park, California,
Chesapeake Beach, Huntingtown, Dunkirk, North Beach, Lusby,
Prince Frederick, Germantown, Damascus, Bethesda, Rockville,
Gaithersburg, Silver Spring, Lisbon, Columbia, Ellicott City,
Jarrettsville, Aberdeen, Staunton, Waynesboro, Stuarts Draft,
Harrisonburg, Strasburg, Woodstock, Mount Jackson, New Market,
Winchester, Luray, Shenandoah, Stanley, Front Royal, Berryville,
Lovingston, Charlottesville, Stanardsville, Madison, Orange,
Gordonsville, Culpeper, Dale City, Manassas, Woodbridge,
Lake Ridge, Montclair, Reston, Herndon, Annandale, Centreville,
Chantilly, McLean, Franconia, Arlington, Alexandria, Falmouth,
Fredericksburg, Dahlgren, Warrenton, Turnbull, Purcellville,
Leesburg, Ashburn, Sterling, Big Meadows, Wintergreen, Paw Paw,
Martinsburg, Charles Town, and Shepherdstown
547 PM EDT Tue Jul 24 2018

...TREES TOPPLING DUE TO SATURATED GROUND...

The recent heavy rainfall of the last several days has left the
ground extremely saturated. This is causing many trees to topple
even with little or no wind. If you live in or drive through
wooded areas, remain especially alert for the potential of downed
trees. Consider altering your route or staying in the interior of
the lowest level of your home or office to avoid weakened trees
that may fall tonight and tomorrow.

$$

DHOF

That’s a new one in the SPS arsenal.

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poolz1

poolz1

Posted
Posted

Went for a run on the C&O this afternoon....several large trees down along the way. These were new falls...add these to the ones that the heavy rains knocked down earlier in the season and there is quite a bit. No sycamores down tho...those things must have one heck of a root system..

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dailylurker

dailylurker

Posted
Posted

I've been getting crushed since Saturday. I've picked up another 2.60" since 6:40am this morning. I've had 13.05" since Saturday. I don't have a fancy rain gauge, so that's a very good estimate. Regardless.. were waterlogged like crazy. Radar suggests my area isn't done for tonight. Radar lighting up to my SE.

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mdhokie

mdhokie

Posted
Posted
2 minutes ago, EastCoast NPZ said:

Managed to nickel and dime my way to over 1" today.  Better than nothing.  Get the grass greened up a bit, at least.  Brings event total to just over 1.5", or about 10" less than the region median.

We had a couple drops from a passing shower, but the rest of the day was bright and sunny in Ocean City :). So feel better, there are places that got less rain than you!

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