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Phillyfan

July 11 2019 | Severe Storms and Flooding

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Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1216 PM CDT Wed Jul 10 2019

   Valid 111200Z - 121200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO
   VALLEY AND LOWER GREAT LAKES INTO THE MID ATLANTIC...

   ...SUMMARY...
   Strong thunderstorms posing a risk for potentially damaging wind
   gusts are expected to develop across parts of the upper Ohio Valley,
   lower Great Lakes region, and Mid Atlantic Thursday afternoon into
   the evening.

   ...Lower Great Lakes/OH Valley into the Mid Atlantic...
   A shortwave trough initially centered from near the southern tip of
   Hudson Bay into the Lower Great Lakes will move eastward on
   Thursday. In conjunction with this trough, a surface low will move
   into Quebec and a trailing cold front will move across the OH Valley
   and Allegheny Plateau. Midlevel lapse rates are forecast to
   generally remain modest, but low-level moisture will be sufficient
   to support at least moderate buoyancy, with MLCAPE potentially
   rising above 2000 J/kg in areas where stronger heating occurs.
   Effective shear of 25-35 kt will support some storm organization,
   especially where stronger instability is realized. 

   Scattered thunderstorm development is possible by early afternoon
   along the cold front from the OH Valley into the lower Great Lakes,
   with additional development also expected further east into portions
   of the Mid Atlantic, given negligible capping across the warm
   sector. Multicell clusters will likely be the dominant mode, with an
   attendant risk of damaging wind and perhaps some marginally severe
   hail. In areas where surface winds are locally backed, due either to
   terrain features or mesoscale surface boundaries, some supercell
   potential may evolve as well. Any supercell would be accompanied by
   a somewhat greater risk of hail and perhaps a brief tornado, in
   addition to the damaging wind threat.  

   ...Central Gulf Coast...
   NHC is forecasting the development of a tropical cyclone across the
   north-central Gulf of Mexico on Thursday. The system is forecast to
   move west-southwestward through the first half of the period, with a
   potential turn more to the west-northwest tomorrow night. Low-level
   flow fields will strengthen as the system intensifies, though the
   westerly motion of the cyclone and forecast for the center to remain
   well offshore through the period are not ideal for a TC tornado
   threat. A brief tornado threat cannot be ruled out near the central
   Gulf Coast, especially later in the period as the system
   intensifies. Locally damaging wind gusts will also be possible,
   especially across portions of central/western LA and the upper TX
   coast during the afternoon/evening, where strong
   heating/destabilization is possible prior to scattered thunderstorm
   development, within a regime of modestly increasing northeasterly
   flow in response to the deepening cyclone. 

   ...Northeast ND into northern MN...
   Midlevel flow will increase substantially across ND into northern MN
   during the day on Thursday, as a fast-moving shortwave trough
   traverses the Canadian Prairies. A surface low attendant to the
   shortwave will move into southern MB by tomorrow evening, as a
   trailing cold front moves through the northern Plains. With
   initially modest low-level moisture and a tendency for the strongest
   large-scale ascent to remain north of the international border, the
   potential for convection along the front into northeast ND/northwest
   MN remains highly uncertain. However, wind profiles and instability
   will be favorable for organized convection, and there will be a
   conditional severe risk with any storms that develop in situ along
   the cold front and/or move into the region from southern MB.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:   2%     - Marginal
   Wind:     15%     - Slight
   Hail:      5%     - Marginal

day2otlk_1730 (1).gif

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Just a morning downpour to get today started why not...

...FLASH FLOOD WATCH IN EFFECT FROM 2 PM EDT THIS AFTERNOON
THROUGH LATE TONIGHT...

The National Weather Service in Mount Holly has issued a

* Flash Flood Watch for portions of northern Delaware, northeast
  Maryland, New Jersey, and Pennsylvania, including the
  following areas, in northern Delaware, New Castle. In
  northeast Maryland, Cecil. In New Jersey, Camden, Gloucester,
  Hunterdon, Mercer, Middlesex, Morris, Northwestern Burlington,
  Salem, Somerset, and Warren. In Pennsylvania, Berks, Delaware,
  Eastern Chester, Eastern Montgomery, Lehigh, Lower Bucks,
  Northampton, Philadelphia, Upper Bucks, Western Chester, and
  Western Montgomery.

* From 2 PM EDT this afternoon through late tonight

* Showers and thunderstorms this afternoon and tonight will be
  capable of producing torrential rainfall, with local amounts of
  1 to 3 inches with locally higher amounts potentially occurring
  in a short period of time. This could lead to localized flash
  flooding.

* The risk of flash flooding is highest in urbanized and low-
  lying areas. Rapid rises on small creeks and streams are
  possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means that there is the potential for flash
flooding which can be life-threatening. Heavy rain is expected to
occur over a short period of time. Rapidly rising flood waters may
quickly inundate roadways and areas of poor drainage. Streams and
creeks could leave their banks, flooding nearby properties.

Please monitor the forecast, especially if you live in a location
that is prone to flooding. Be prepared to take action if a flash
flood warning is issued for your area.
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Kbuf

Things still look to become active fairly quickly mid to late this
afternoon with showers and thunderstorms expected to develop rapidly
with the arrival of a potent mid level shortwave and just ahead of a
surface cold front. By this time, MLCAPES should be in the 1500-2500
J/Kg range. Convection will quickly become widespread by later this
afternoon, and will move eastward along with the mid level
shortwave/surface cold front through this evening.

BUFKIT soundings showing forecast precipitable water values have
come down a bit from around 2 inches with earlier guidance, to
generally around 1.75 inches overall for this afternoon/evening as
moisture continues to advect into the region ahead of the trough and
cold front. By no means does this mitigate a heavy rain threat with
any thunderstorms, however does make the flash flood risk even a bit
less. Training of storms would most likely be needed to produce a
flash flood threat, as storm motion should be sufficient to limit
residence time of storms over one particular area. The forecasted
lower PWAT values are owed to an area somewhat drier air in the mid
levels, so while this may help to aid in even less of a widespread
flooding risk, it will increase the chances a for severe weather
some from mid afternoon into this evening.

The mid-level flow will be weak through early afternoon, with 700 mb
winds only 10-15 knots. 700 mb winds will increase to 25-30 knots
late afternoon and early evening which will provide modest storm
motion. Since storms are not expected to develop until after winds
aloft increase with the approach of the shortwave, the potential for
widespread flooding is limited as mentioned above. Any storms that
do develop early afternoon will have to be closely monitored since
they will be slower moving and because they may saturate the ground
ahead of more widespread convection expected later this afternoon.
Even if storms are moving, the potential for heavy rain (and flash
ponding) is still there with warm cloud processes occurring as
wbzero heights rise to 14 kft and warm cloud depth (temps warmer
than -10c) increase to to 18 kft.

SPC continues to have our area in a slight risk for severe weather
today with gusty winds the main concern, with a lesser risk of large
hail possible in a few storms. Modest 0-6 km shear continues to be
main limiting factor for a more robust severe event. However, there
will still be enough shear in place for some storm organization
considering the more than ample instability. Expect high storm tops
with a risk for pulse severe weather along with a few stronger
organized storms if there is locally higher shear due to lake
breezes or with support from the shortwave.

https://forecast.weather.gov/product.php?site=BUF&issuedby=BUF&product=AFD&format=CI&version=1&glossary=1&highlight=off

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SPC MESO Discussion for possible watch.

Source: https://www.spc.noaa.gov/products/md/

image.png.8945b390e0220bda624a3f1e1da60190.png

TEXT:

Quote

 Mesoscale Discussion 1434
   NWS Storm Prediction Center Norman OK
   1151 AM CDT Thu Jul 11 2019

   Areas affected...northern VA...MD...DE and southeast PA

   Concerning...Severe potential...Watch possible 

   Valid 111651Z - 111815Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Thunderstorms will increase in coverage and intensity this
   afternoon. A few damaging gusts are possible and trends are being
   monitored for possible watch issuance.

   DISCUSSION...Widely scattered thunderstorms are beginning to develop
   over the higher terrain of central and northern VA into southeast
   PA. Cloud cover across this area has not been as much of a hindrance
   compared to areas to the north, and temperatures have warmed into
   the mid 80s to low 90s F with dewpoints in the low to mid 70s F.
   Midlevel lapse rates are rather poor, but this warm and very moist
   airmass is resulting in MLCAPE values of 1500-2000 J/kg. This area
   lies on the southern periphery of modest effective shear of 20-30
   kt, with high PW values approaching 2 inches. Upper forcing for
   ascent will modestly increase as the upper shortwave trough shifts
   eastward toward the lower Great Lakes and central Appalachians later
   this afternoon, but overall severity/organization will be limited
   somewhat in the absence of steep midlevel lapse rates and strong
   deep layer flow. Nevertheless, some forward propagating clusters
   will be possible through storm and outflow interactions, which could
   result in a few strong/severe gusts through the afternoon.
   Convective trends will be monitored and a watch may become necessary
   in the next few hours.

   ..Leitman/Grams.. 07/11/2019

 

Edited by Wx_WhatWX?
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pwat.conus.png

Good chance it rains hard.  Flash flood watches up from Upton as well for NENJ and 5 boroughs

Spoiler

Flood Watch
National Weather Service New York NY
1250 PM EDT Thu Jul 11 2019

...FLASH FLOODING POSSIBLE LATE TODAY INTO TONIGHT...

NYZ072>075-176-178-120600-
/O.EXA.KOKX.FF.A.0005.190711T2000Z-190712T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New York (Manhattan)-Bronx-Richmond (Staten Island)-
Kings (Brooklyn)-Northern Queens-Southern Queens-
1250 PM EDT Thu Jul 11 2019

...FLASH FLOOD WATCH IN EFFECT FROM 4 PM EDT THIS AFTERNOON
THROUGH LATE TONIGHT...

The National Weather Service in Upton has expanded the

* Flash Flood Watch to include New York City.

* From 4 PM EDT this afternoon through late tonight

* Showers and thunderstorms with an approaching warm front will
  increase in coverage this afternoon and evening, with the rain
  becoming heavy at times from late today into this evening.

* Rainfall rates of one inch per hour or more, for greater than
  one hour, will be possible.

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.

&&

$$


Flood Watch
National Weather Service New York NY
1250 PM EDT Thu Jul 11 2019

...FLASH FLOODING POSSIBLE LATE TODAY INTO TONIGHT...

NJZ002-004-006-103>108-120600-
/O.CON.KOKX.FF.A.0005.190711T2000Z-190712T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Western Passaic-Eastern Passaic-Hudson-Western Bergen-
Eastern Bergen-Western Essex-Eastern Essex-Western Union-
Eastern Union-
1250 PM EDT Thu Jul 11 2019

...FLASH FLOOD WATCH REMAINS IN EFFECT FROM 4 PM EDT THIS
AFTERNOON THROUGH LATE TONIGHT...

The Flash Flood Watch continues for

* All of northeast New Jersey, including the following areas,
  Bergen, Essex, Passaic, Union, and Hudson counties.

* From 4 PM EDT this afternoon through late tonight

* Showers and thunderstorms with an approaching warm front will
  increase in coverage this afternoon and evening, with the rain
  becoming heavy at times from late today into this evening.
  Excessive runoff could lead to flash flooding of urban and
  poor drainage areas. Some fast-responding small streams could
  approach or exceed bank full.

* Rainfall of 1 to 2 inches is likely, and local amounts up to 3
  inches are possible. Rainfall rates of one inch per hour or
  more are possible.

 

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Busy here on in the East!

image.thumb.png.51f186185fdd41ba27ee7cefdbec83ad.png

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Was gorgeous this morning while up at bear mountain in ny.  Getting dark here in little ferry with a rather strong breeze out of the east. 

Edited by STEVE392
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20 hours ago, Phillyfan said:

Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1216 PM CDT Wed Jul 10 2019

   Valid 111200Z - 121200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO
   VALLEY AND LOWER GREAT LAKES INTO THE MID ATLANTIC...

   ...SUMMARY...
   Strong thunderstorms posing a risk for potentially damaging wind
   gusts are expected to develop across parts of the upper Ohio Valley,
   lower Great Lakes region, and Mid Atlantic Thursday afternoon into
   the evening.

   ...Lower Great Lakes/OH Valley into the Mid Atlantic...
   A shortwave trough initially centered from near the southern tip of
   Hudson Bay into the Lower Great Lakes will move eastward on
   Thursday. In conjunction with this trough, a surface low will move
   into Quebec and a trailing cold front will move across the OH Valley
   and Allegheny Plateau. Midlevel lapse rates are forecast to
   generally remain modest, but low-level moisture will be sufficient
   to support at least moderate buoyancy, with MLCAPE potentially
   rising above 2000 J/kg in areas where stronger heating occurs.
   Effective shear of 25-35 kt will support some storm organization,
   especially where stronger instability is realized. 

   Scattered thunderstorm development is possible by early afternoon
   along the cold front from the OH Valley into the lower Great Lakes,
   with additional development also expected further east into portions
   of the Mid Atlantic, given negligible capping across the warm
   sector. Multicell clusters will likely be the dominant mode, with an
   attendant risk of damaging wind and perhaps some marginally severe
   hail. In areas where surface winds are locally backed, due either to
   terrain features or mesoscale surface boundaries, some supercell
   potential may evolve as well. Any supercell would be accompanied by
   a somewhat greater risk of hail and perhaps a brief tornado, in
   addition to the damaging wind threat.  

   ...Central Gulf Coast...
   NHC is forecasting the development of a tropical cyclone across the
   north-central Gulf of Mexico on Thursday. The system is forecast to
   move west-southwestward through the first half of the period, with a
   potential turn more to the west-northwest tomorrow night. Low-level
   flow fields will strengthen as the system intensifies, though the
   westerly motion of the cyclone and forecast for the center to remain
   well offshore through the period are not ideal for a TC tornado
   threat. A brief tornado threat cannot be ruled out near the central
   Gulf Coast, especially later in the period as the system
   intensifies. Locally damaging wind gusts will also be possible,
   especially across portions of central/western LA and the upper TX
   coast during the afternoon/evening, where strong
   heating/destabilization is possible prior to scattered thunderstorm
   development, within a regime of modestly increasing northeasterly
   flow in response to the deepening cyclone. 

   ...Northeast ND into northern MN...
   Midlevel flow will increase substantially across ND into northern MN
   during the day on Thursday, as a fast-moving shortwave trough
   traverses the Canadian Prairies. A surface low attendant to the
   shortwave will move into southern MB by tomorrow evening, as a
   trailing cold front moves through the northern Plains. With
   initially modest low-level moisture and a tendency for the strongest
   large-scale ascent to remain north of the international border, the
   potential for convection along the front into northeast ND/northwest
   MN remains highly uncertain. However, wind profiles and instability
   will be favorable for organized convection, and there will be a
   conditional severe risk with any storms that develop in situ along
   the cold front and/or move into the region from southern MB.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:   2%     - Marginal
   Wind:     15%     - Slight
   Hail:      5%     - Marginal

day2otlk_1730 (1).gif

Now, I know a thing or two about maths, but I'm always at something of a loss to understand how to interpret a "2% chance of Tornado," which is what that map tells me that I have.

Does it mean that for every 50 times I get a warning like this, I should expect one tornado?  Because I think I've gotten two or three of those warnings this year alone.  I'm pretty sure that I've never had a tornado on this property, in all of recorded history.  I'm not sure if there has ever even been one in my town.

I get that the risk isn't zero, and I appreciate the "directional data."  I'm just not sure what it actually measures.

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We lucked out here with that heavy slug of rain that whacked pittsburgh going southwest of us and at worst received moderate rate rains.  

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Been stuck in the rain-less donut hole so far...hoping this fills in...

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serious storms in the hills. flooding will be a problem for many shortly. 

wow, this rain. just again and again. 

Tremendous rainfall. 

Edited by MDBlueRidge
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Oh crap! Here we go again with the extremely heavy rain. Just like last summer, sounds like a jet flying overhead from the rain just POUNDING on the canvas awning. The dp was 75.8 prior to the rain. I can't believe how hard it's raining right now, honestly. 

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3hr radar estimate in NNJ

image.png.6ada429e6226c73c18222c63ffd4e4d8.png

And PHL

image.png.82f9ddafc27b6954ed6a141fadb2468b.png

Edited by StretchCT

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Ahh - my old stomping grounds under flash flood warning with 2.5"  of rain already in the bucket.

Flash flood warning

Spoiler

Flash Flood Statement
National Weather Service New York NY
311 PM EDT Thu Jul 11 2019

NJC013-112130-
/O.CON.KOKX.FF.W.0002.000000T0000Z-190711T2130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Essex NJ-
311 PM EDT Thu Jul 11 2019

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 530 PM EDT FOR
CENTRAL ESSEX COUNTY...

At 309 PM EDT, Doppler radar indicated showers and thunderstorms
producing heavy rain across the warned area. Up to two and a half
inches of rain have already fallen. Flash flooding may already be
occurring.

Some locations that will experience flooding include...
Bloomfield, Orange, Caldwell, East Orange, West Orange, Montclair,
Belleville, Nutley, Verona, Cedar Grove, Glen Ridge, North Caldwell
and East Newark.

An additional one inch of rainfall is possible in the warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Flood advisory

Spoiler

Flood Advisory
National Weather Service New York NY
325 PM EDT Thu Jul 11 2019

NJC013-017-039-NYC085-112130-
/O.CON.KOKX.FA.Y.0050.000000T0000Z-190711T2130Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hudson NJ-Union NJ-Essex NJ-Richmond NY-
325 PM EDT Thu Jul 11 2019

...THE URBAN AND SMALL STREAM FLOOD ADVISORY REMAINS IN EFFECT UNTIL
530 PM EDT FOR HUDSON...UNION...ESSEX AND RICHMOND COUNTIES...

At 324 PM EDT, Doppler radar indicated heavy rain that will cause
urban and small stream flooding in the advisory area. One to two
inches with locally higher amounts of rain have already fallen.

Some locations that will experience flooding include...
Newark, Jersey City, Elizabeth, Bayonne, Plainfield, Bloomfield,
Linden, Orange, Summit, Millburn, Secaucus, Harrison, Todt Hill,
Caldwell and Huguenot.

 

Edited by StretchCT

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Just went over an inch, raining at a rate of over 3"/hour right now. 

  • Wow! 2

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EPA under flash flood warnings as well

304343863_epaflashflood.PNG.c90a1a913a2442b5c84c2a015c482950.PNG

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10 minutes ago, lynniethelurker said:

Just went over an inch, raining at a rate of over 3"/hour right now. 

Still raining up here but not like it was when it started at 2:20pm.  My gauge looks to be approaching 4"

  • Wow! 1

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2 hours ago, telejunkie said:

Been stuck in the rain-less donut hole so far...hoping this fills in...

What does the bolded term mean?

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16 minutes ago, MDBlueRidge said:

What does the bolded term mean?

In your area it is referred to as "dry-couch" conditions

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14 minutes ago, Miller A said:

In your area it is referred to as "dry-couch" conditions

*wipes brow* 

thank you sir. 

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