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9/26 Slight Risk Severe Storms/Heavy Rain Obs Because It Has Been Hours Since It Last Rained Heavily


Bananashadow
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...Northeast into the central Appalachians and Mid-Atlantic
   states...
   A potent mid-level trough located over the western Great Lakes this
   morning will rapidly move northeast glancing the lower Great Lakes
   by early evening and New England after dark.  Strong 500mb height
   falls will primarily remain north of the international border but
   weak height falls will likely extend as far south as PA.  Coincident
   with the mid-level trough, a belt of strengthening southwesterly
   500mb flow (50-70kt) will overspread western NY and New England. 
   Early day clouds and scattered showers over the Northeast and weak
   mid-level lapse rates will limit destabilization, but the moist
   airmass coupled with pockets of modest heating amidst thinning cloud
   cover.  Southerly low-level flow will enable an appreciably moist
   boundary layer to infiltrate much of New England by early afternoon.
    A couple of broken bands of convection will likely develop by
   midday in lee of the lower Great Lakes with these bands intensifying
   during the afternoon.  Lengthening hodographs suggest some tendency
   to maintain some cellular character and the possibility for a couple
   of supercells is seemingly highest during the afternoon from the
   Adirondacks eastward into southwestern ME and south into the lower
   Hudson Valley.  The most favorable hodographs will likely remain
   confined in the VT/NH/ME vicinity, but may in a mesoscale area
   farther south become more supportive of transient storm-scale
   rotation.  Of particular note, the 00Z GFS appears as the outlier
   over southeast NY where terrain-channeled flow will probably
   maintain a larger hodograph structure rather than the veered
   low-level wind profile depicted by the GFS.  Damaging winds are the
   predominant hazard with the stronger storms but a tornado or two is
   possible prior to nightfall.  

   Farther south, a couple of clusters/small bands will likely develop
   during the afternoon over the higher terrain before moving east into
   lower elevations of MD/eastern PA and NJ by late in the day. 
   Isolated to widely scattered damaging winds are the main threat with
   the stronger storms.  This activity will likely weaken during the
   early evening.
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23 minutes ago, Rainshadow said:

Latest HRRR :wub:  Feb, Mitch & PAWxNut more than the rest of us.

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Predicted to weaken after this hour.

RGEM likes the same general area at the same timeframe. Seems like a good bet for at a minimum a round of torrential rain for many of us. Hopefully it lasts less than 30 minutes as it rolls through.

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With both KDIX and KDOX out of service, tracking the storms this afternoon and evening could be challenging in the Philly area.  TPHL & TEWR fill in the dead areas a bit?

Quote

Message Date: Sep 26 2018 10:13:39 KDIX IS OFF LINE DUE TO AN EQUIPMENT FAILURE. TECHNICIANS HAVE BEEN NOTIFIED. RE TURN TO SERVICE IS UNKNOWN AT THIS TIME. WE APOLOGIZE FOR ANY INCONVENIENCE.

 

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From SPC MSD #1504 - doesn’t this seem to contradict itself? These parameters don’t seem like a “marginal storm environment” to me...

 

...”There is enough instability to support thunderstorm development (MLCAPE of 1000-1500 J/kg), and shear (effective bulk shear of 35-45 knots) is better across the northern half of the discussion are (southern PA, northern MD/VA), which could produce a few rotating storms within a broken line of storms this afternoon/evening. A watch is unlikely given the overall marginal storm environment and isolated severe risk, but southern PA/vicinity could be included in a watch depending on storm evolution.”

 

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55 minutes ago, JimCaruso said:

From SPC MSD #1504 - doesn’t this seem to contradict itself? These parameters don’t seem like a “marginal storm environment” to me...

 

...”There is enough instability to support thunderstorm development (MLCAPE of 1000-1500 J/kg), and shear (effective bulk shear of 35-45 knots) is better across the northern half of the discussion are (southern PA, northern MD/VA), which could produce a few rotating storms within a broken line of storms this afternoon/evening. A watch is unlikely given the overall marginal storm environment and isolated severe risk, but southern PA/vicinity could be included in a watch depending on storm evolution.”

 

Maybe because the discussion goes down thru Virginia.  #1503 just to the north said a watch was possible.  Reads like they are trying to fit in max shear and ml cape which almost looks like the boundary between discussions.

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Above average light show as line approaches

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
706 PM EDT WED SEP 26 2018

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Northwestern New Castle County in northern Delaware...
  Northeastern Kent County in northeastern Maryland...
  Cecil County in northeastern Maryland...
  Southeastern Berks County in eastern Pennsylvania...
  Montgomery County in southeastern Pennsylvania...
  Chester County in southeastern Pennsylvania...
  Western Delaware County in southeastern Pennsylvania...

* Until 800 PM EDT.

* At 705 PM EDT, severe thunderstorms were located along a line
  extending from near Birdsboro to near Delta, moving east at 30 mph.

  HAZARD...60 mph wind gusts and penny size hail.

  SOURCE...Radar indicated.

  IMPACT...Damage to roofs, siding, trees, and power lines is
           possible.

* Locations impacted include...
  Wilmington, Newark, West Chester, Elkton, Calvert, Norristown,
  Pottstown, Phoenixville, Lansdale, West Norriton, East Norriton,
  Coatesville, Westtown, Downingtown, Conshohocken, Souderton,
  Ambler, Elsmere, Kennett Square and Birdsboro.

 

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Meh here, but impressive how the razor thin line extends from Maine to Florida....


Anybody happen to have a screen capture of the full length of the line that they can post? I was out at a business event in the city last night during the action so wasn’t able to monitor (except enough to know that a line of storms was approaching, but I couldn’t get any sense of anything being in a large building).
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1 hour ago, JimCaruso said:

 


Anybody happen to have a screen capture of the full length of the line that they can post? I was out at a business event in the city last night during the action so wasn’t able to monitor (except enough to know that a line of storms was approaching, but I couldn’t get any sense of anything being in a large building).

 

line.JPG.bc22d584e3e4932e5c78aaf634cad915.JPG

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