2020 Mid-Atlantic Severe Weather - General Thread

[09-10 analogy]

Real localized disappointment in upper NW. Rain, not much wind, thunder and lightning on the periphery. Last evening it looked like the N Bethesda storm could get us here as well but the core of it stayed NW. Then another cell shortly afterwards seemed to be riding the NW boundary between DC and MD on radar, aimed squarely at MBY, but it seemed as if it just pulsed out right overhead. These things are really hit and miss usually, but that's nothing new. Maybe better luck today. 

 

[mappy]

had some boomers roll through around 9pm and 11pm last night. probably more after that but slept through it. 

woke up with over an inch in the gauge. which was fine, pool needed the water.

[osfan24]

Looks like everything is just a little too fast/east for us today. Onto the weekend.

[ErinInTheSky]

1 hour ago, mappy said:

had some boomers roll through around 9pm and 11pm last night. probably more after that but slept through it. 

woke up with over an inch in the gauge. which was fine, pool needed the water.

I had 4 distinct thunderstorms train over me in Germantown last night. It was so awesome. The first split/fringed me, but then 3 more in a row.

[North Balti Zen]

Something popped up over downtown Baltimore and it absolutely poured here for about 20 minutes. Checked with home and five miles up 83...nothing.

[mappy]

14 minutes ago, North Balti Zen said:

Something popped up over downtown Baltimore and it absolutely poured here for about 20 minutes. Checked with home and five miles up 83...nothing.

oh damn, just looked at radar. didn't realize it was pouring baltimore south

[high risk]

3 hours ago, osfan24 said:

Looks like everything is just a little too fast/east for us today. Onto the weekend.

        Since I assume you're referring to severe potential here in the severe thread, there's no severe potential this weekend or anywhere on the horizon.      While there could be some convective elements in the Sunday-??? period within the rain, it looks like easterly flow over a deep layer and cool surface temperatures.

[high risk]

And I should note that part of this subforum is still in the game today, with cape and modest deep layer shear still in place.     The CAMs show the threat as mostly DC and points south and east, but I still have a 71 dew point here in southern Howard County, so I'm not totally ready to write things off for those just north of DC either.

[osfan24]

4 minutes ago, high risk said:

        Since I assume you're referring to severe potential here in the severe thread, there's no severe potential this weekend or anywhere on the horizon.      While there could be some convective elements in the Sunday-??? period within the rain, it looks like easterly flow over a deep layer and cool surface temperatures.

I was thinking more of a flash flood threat, but the latest model runs don't look as good for this weekend/next week.

[high risk]

2 minutes ago, osfan24 said:

I was thinking more of a flash flood threat, but the latest model runs don't look as good for this weekend/next week.

       gotcha.    and yeah, the 12z guidance seems to be moving the heaviest rain south -  we'll see if that's a blip or a legit trend.      Either way, the flooding threat will probably be there for some (i.e. lots of rain adding up over a multi-day period); whether it's a flash flood threat will depend upon whether we can get some clearing and heating near the upper low for convection.     Right now, it just looks cloudy and cool.

[Rhino16]

I think I’m going to go through this gap between these storms north and south of me... then it will probably be quiet again for another month. Every single storm has pretty much misses us in the past month... something about northern and southeastern VA looks tasty for the storms or something, during both summer and winter.

[Kmlwx]

CIPS is seeing something around hr144. 

[high risk]

Trying to make some sense of the CIPS lighting up.       It's based off of the GEFS, and some of the recent GEFS means for next week look healthy.   I grabbed the 18z (the analog was from the 00z cycle, but the 18z 500 map is arguably a bit better....).      Anyhow, this is a great look at 500 mb, but of note, neither the Euro ops or ensemble looks anything close to this amplified.

  

[yoda]

I know technically it doesn't say Mid Atlantic in the SPC text for the SPC 4-8 day OTLK... but this could be promising and maybe what was being picked up on as @Kmlwx and @high risk posted about above:

 Day 5 and beyond - Pattern will remain characterized by a broad
   trough in the east, and potential for northwest flow mcs/severe
   events will persist from portions of the central and southern Plains
   through the OH Valley at least into days 5-7. However,
   predictability in this regime is inherently low.

[Kmlwx]

June 10, 2008 has been showing up in some of the CIPS analogs. Last night's run it's for the 120 hour mark. 

[high risk]

2 hours ago, Kmlwx said:

June 10, 2008 has been showing up in some of the CIPS analogs. Last night's run it's for the 120 hour mark. 

      Interesting.      Seems like the f144 would be the best shot at svr....     In terms of the progged 500 maps, you have to get excited when you see the day 5 maps showing an impressive trough to our west.     The problem is that instead of it overspreading the mid-Atlantic, most guidance either lifts it to the northeast, weakens it, or both.     As a result, the progged height falls over our area are really meh in the GFS, GEFS, and Euro ensemble.     The deterministic Euro, though, is better and would imply svr chances here on day 6.

 

[Kmlwx]

9 minutes ago, high risk said:

      Interesting.      Seems like the f144 would be the best shot at svr....     In terms of the progged 500 maps, you have to get excited when you see the day 5 maps showing an impressive trough to our west.     The problem is that instead of it overspreading the mid-Atlantic, most guidance either lifts it to the northeast, weakens it, or both.     As a result, the progged height falls over our area are really meh in the GFS, GEFS, and Euro ensemble.     The deterministic Euro, though, is better and would imply svr chances here on day 6.

 

The extended CIPS page has a good signal at hr168 too. This has a been a weird met summer so far...and spring for that matter. Maybe the atmosphere is having COVID hangover like we all are. 

[high risk]

26 minutes ago, Kmlwx said:

The extended CIPS page has a good signal at hr168 too. This has a been a weird met summer so far...and spring for that matter. Maybe the atmosphere is having COVID hangover like we all are. 

  hahaha!       The bottom line is that with a big trough sitting to our west during a chunk of next week and moving towards the coast, there will be opportunities for severe in the east, with timing and other details obviously impossible to nail at long forecast lengths.     

[AdamHLG]

3 hours ago, Kmlwx said:

This has a been a weird met summer so far...and spring for that matter. 

Don't forget the abysmal winter before that either!  

[Kmlwx]

I was just reviewing 2008 - severe weenies were truly spoiled that year. Not only did we have regular severe...

We had MDTs on May 31, and then June 4, 10, 16. That's for moderates in just over half a month. Dang impressive considering we can go years in some cases without a moderate at all. It's tough enough to get decent slight risk days every few days for a good stretch...

[southmdwatcher]

A few months late for Kmlwx.  Here are some of the color tables, I use on GR2Analyst.  One transparent for BR.  Two BV's first one is transparent so it might not show up well enough, second BV is what I use regularly. One SRV and one NROT.  Sorry for the length of the color tables.

 

Quote

Product:BR
Units: DBZ
Step: 10

color4: -30 128 21 0    55
color4: -10 109 110 154   55
color4: 0 180 251 255    55
color4: 10 86 121 211    55
color: 20 28 212 18 9 78 0
color: 35 243 241 16 253 186 7
color: 40 255 172 8 255 122 16
color: 50 233 4 0 104 0 6
color: 60 103 0 216 245 106 247
color: 70 255 159 255 255 238 255
color: 80 56 197 255 0 72 71
color: 90 4 48 49 0 0 0

Quote

Product: BV
units: KTS
step: 5

color4: 0 128 128 128    55 
color: 10 86 0 0    
color: 35 243 33 14    
color: 45 255 114 51
color: 60 255 255 0
color: 120 92 255 0
color4: -10 12 62 36    55
color: -40 35 185 110    
color: -50 90 221 155    
color: -60 221 216 253
color: -120 0 14 255

Quote

Product: BV
units: KTS
step: 5
Scale:  1.9426        ; converts internal units (M/S) to KTS

color: 0 128 128 128 
color: 10 86 0 0
color: 35 243 33 14
color: 45 255 114 51
color: 60 255 255 0
color: 120 92 255 0
color: -10 12 62 36
color: -40 35 185 110
color: -50 90 221 155
color: -60 221 216 253
color: -120 0 14 255

Quote

;=======================================
;
; GR Storm Relative Velocity color table
;
;   Internal units are in meters/second (M/S) so we use the
;   Scale: statement to let the program know that the values
;   in this table are in knots (KTS)
;

Product: SRV
Units: Kts
Scale: 1.9426
Step: 41

color:    -123.4    132    4    148
color:    -114.7    126    4    149
color:    -108.8    120    4    150
color:    -102.9    114    4    151
color:    -99    108    4    152
color:    -98.1    93    5    153
color:    -97.1    85    5    153
color:    -96.2    77    4    153
color:    -95.2    69    4    153
color:    -94.3    61    3    153
color:    -93.3    52    3    153
color:    -92.4    44    3    153
color:    -91.4    36    2    153
color:    -90.5    28    2    153
color:    -89.5    22    2    153
color:    -88.6    22    12    156
color:    -87.6    23    23    160
color:    -86.7    24    34    163
color:    -85.7    25    44    167
color:    -84.8    26    55    170
color:    -83.8    27    66    174
color:    -82.9    28    76    177
color:    -81.9    29    87    181
color:    -81    30    98    184
color:    -80    31    108    188
color:    -79    32    119    192
color:    -78    33    130    195
color:    -77    34    140    199
color:    -76    35    151    202
color:    -75    36    162    206
color:    -74    37    172    209
color:    -73    38    183    213
color:    -72    39    194    216
color:    -71    40    204    220
color:    -70    48    224    227
color:    -69    52    224    227
color:    -68    58    224    227
color:    -67    65    225    228
color:    -66    71    226    229
color:    -65    78    226    229
color:    -64    84    227    230
color:    -63    91    228    231
color:    -62    97    229    232
color:    -61    104    229    232
color:    -60    110    230    233
color:    -59.1    117    231    234
color:    -58.1    123    231    234
color:    -57.2    130    232    235
color:    -56.2    136    233    236
color:    -55.3    143    234    237
color:    -54.4    149    234    237
color:    -53.4    156    235    238
color:    -52.5    162    236    239
color:    -51.6    169    236    239
color:    -50.6    175    237    240
color:    -49.7    182    238    241
color:    -48.8    167    241    218
color:    -47.8    154    242    200
color:    -46.9    140    243    181
color:    -45.9    127    245    163
color:    -45    113    246    144
color:    -44    100    247    126
color:    -43    87    248    108
color:    -42    73    250    89
color:    -41    60    251    71
color:    -40    46    252    52
color:    -39    33    253    34
color:    -38    3    250    3
color:    -37    3    245    3
color:    -36    3    240    3
color:    -35    3    234    3
color:    -34    3    229    3
color:    -33    3    224    3
color:    -32    3    219    3
color:    -31    3    213    3
color:    -30    3    208    3
color:    -29    3    203    3
color:    -28    3    198    3
color:    -27    3    192    3
color:    -26    3    187    3
color:    -25    3    182    3
color:    -24    3    177    3
color:    -23    2    171    2
color:    -22    2    166    2
color:    -21    2    161    2
color:    -20    2    156    2
color:    -19    2    150    2
color:    -18    2    145    2
color:    -18.1    2    140    2
color:    -17.1    2    135    2
color:    -16.2    2    129    2
color:    -15.2    2    124    2
color:    -14.3    2    119    2
color:    -13.3    2    114    2
color:    -12.4    2    108    2
color:    -11.4    2    103    2
color:    -10.5    5    102    3
color:    -9.5    78    121    76
color:    -8.6    82    122    80
color:    -7.6    86    124    84
color:    -6.7    90    125    88
color:    -5.7    94    126    92
color:    -4.8    98    128    96
color:    -3.8    102    129    100
color:    -2.9    106    130    104
color:    -1.9    110    132    108
color:    -1    114    133    112
color:    0    138    118    118
color:    1    138    114    129
color:    1.9    138    108    122
color:    2.9    137    102    115
color:    3.8    136    95    108
color:    4.8    136    89    101
color:    5.7    135    82    94
color:    6.7    134    76    86
color:    7.6    133    69    79
color:    8.6    133    63    72
color:    9.5    132    56    65
color:    10.5    110    0    0
color:    11.4    115    0    0
color:    12.4    121    0    0
color:    13.3    126    0    0
color:    14.3    132    0    1
color:    15.2    137    0    1
color:    16.2    143    0    1
color:    17.1    149    0    2
color:    16.1    154    0    2
color:    18.1    160    0    2
color:    19    165    0    3
color:    20    171    0    3
color:    21    176    0    3
color:    22    182    0    4
color:    23    188    0    4
color:    24    193    0    4
color:    25    199    0    4
color:    26    204    0    5
color:    27    210    0    5
color:    28    215    0    5
color:    29    221    0    6
color:    30    227    0    6
color:    31    232    0    6
color:    32    238    0    7
color:    33    243    0    7
color:    34    250    55    81
color:    35    250    60    89
color:    36    250    65    97
color:    37    250    71    105
color:    38    251    76    113
color:    39    251    82    122
color:    40    251    87    130
color:    41    252    93    138
color:    42    252    98    146
color:    43    252    104    155
color:    44    252    109    163
color:    45    253    115    171
color:    45.9    253    120    179
color:    46.9    253    126    188
color:    47.8    254    131    196
color:    48.8    254    137    204
color:    49.7    255    140    213
color:    50.6    255    149    208
color:    51.6    255    159    203
color:    52.5    255    168    198
color:    53.4    255    178    193
color:    54.4    255    187    188
color:    55.3    255    197    183
color:    56.2    255    206    178
color:    57.2    255    216    173
color:    58.1    255    225    168
color:    59.1    255    232    163
color:    60    255    228    159
color:    61    255    224    155
color:    62    255    219    151
color:    63    255    215    147
color:    64    255    211    142
color:    65    255    206    138
color:    66    255    202    134
color:    67    255    197    130
color:    68    255    193    125
color:    69    255    189    121
color:    70    255    184    117
color:    71    255    180    113
color:    72    255    176    108
color:    73    255    171    104
color:    74    255    167    100
color:    75    255    162    96
color:    76    255    158    91
color:    77    255    154    87
color:    78    255    149    83
color:    79    255    138    79
color:    80    252    135    78
color:    81    248    132    76
color:    81.9    245    129    74
color:    82.9    241    126    72
color:    83.8    238    123    71
color:    84.8    234    120    69
color:    85.7    231    117    67
color:    86.7    227    114    65
color:    87.6    224    111    63
color:    88.6    220    108    62
color:    89.5    216    104    60
color:    90.5    213    101    58
color:    91.4    209    98    56
color:    92.4    206    95    54
color:    93.3    202    92    53
color:    94.3    199    89    51
color:    95.2    195    86    49
color:    96.2    192    83    47
color:    97.1    188    80    45
color:    98.1    185    77    44
color:    99    181    74    42
color:    100    177    70    40
color:    103.9    174    67    38
color:    109.8    170    64    36
color:    116.6    167    61    35
color:  122.6  163     58      33
rf:    127    0    207    
 

Quote

product: NROT
units: NROT
step: .25 
decimals: 2

color4: 0 177 183 186 10
color: .50 201 218 86
color: .75 253 205 30 239 141 47
color: 1.50 236 42 45 236 42 45
color: 1.75 196 48 45 196 48 45
color: 2.00 191 39 145 191 39 145
color: 2.50 224 35 146 224 35 146
color: 3.00 240 129 179 240 129 179
color: 3.50 248    207 205 248 207 205
color: 4.00 255 255 255 255 255 255
color: 4.25 255    255 255
color: -.50 124 139 197
color: -1.00 48 55 149
color: -1.50 0 165 81
color: -3.00 0 41 36
 

 

[Kmlwx]

Thank you! I'll check them out! 

[high risk]

On 6/19/2020 at 4:09 PM, Kmlwx said:

I was just reviewing 2008 - severe weenies were truly spoiled that year. Not only did we have regular severe...

We had MDTs on May 31, and then June 4, 10, 16. That's for moderates in just over half a month. Dang impressive considering we can go years in some cases without a moderate at all. It's tough enough to get decent slight risk days every few days for a good stretch...

           Nice research on this!     2008 was an active svr season for sure, but SPC was handing out MDT risks like Halloween candy.      This was back before ENH existed, and they used MDT more liberally to try and distinguish from the run-of-the-mill SLGT days.       In that respect, adding in the ENH was a very good move, as it allows them to represent those days with a larger coverage of lower end events and save the MDT for days with a decent concentration of higher end events.

            June 4, 2008 was a legit MDT for us, and it's a day I'll always remember.     I guess that June 10 verified as a MDT over upstate New York and New England, although there weren't any high end reports;   the MDT here didn't verify.    May 31 and June 16 definitely would have worked fine with ENH, had that been an option.

 

[Kmlwx]

1 minute ago, high risk said:

           Nice research on this!     2008 was an active svr season for sure, but SPC was handing out MDT risks like Halloween candy.      This was back before ENH existed, and they used MDT more liberally to try and distinguish from the run-of-the-mill SLGT days.       In that respect, adding in the ENH was a very good move, as it allows them to represent those days with a larger coverage of lower end events and save the MDT for days with a decent concentration of higher end events.

            June 4, 2008 was a legit MDT for us, and it's a day I'll always remember.     I guess that June 10 verified as a MDT over upstate New York and New England, although there weren't any high end reports;   the MDT here didn't verify.    May 31 and June 16 definitely would have worked fine with ENH, had that been an option.

 

I think June 4, 2008 stands out for me because of the situation I was in. I had been sneaking peaks at the SPC site and the forums throughout the day. If my memory is correct, I hightailed it home (I walked through a patch of woods from high school to get home back then) and got to watch the bulk of it from home. Grade school made me miss a lot of good events

I think June 29, 2012 takes the cake for me though. Simply watching the reports coming in as it came over the mountains is something I'll never forget. I had friends who were on a boat in the bay texting me and acting like I was downplaying the whole thing. A few days after, a few of them reached out to tell me how right I was and how glad they were that I pretty much forced them back to shore. 

[Kmlwx]

Seems tomorrow and Tuesday could have some iso instances of severe. 

Also - I'm late to the party but it looks like the HRRRv4 is no more. It hasn't been sending data from NCEP - I noticed it on the COD site. Does this mean they'll bring back the v3? Or is v3 the operational?

[yoda]

4 minutes ago, Kmlwx said:

Seems tomorrow and Tuesday could have some iso instances of severe. 

Also - I'm late to the party but it looks like the HRRRv4 is no more. It hasn't been sending data from NCEP - I noticed it on the COD site. Does this mean they'll bring back the v3? Or is v3 the operational?

I was about to ask why no one posted about the AFD lol

[yoda]

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
Multiple days of potential severe weather and heavy rainfall are
becoming increasingly likely.

High pressure will continue to build over the southeastern
CONUS into the Atlantic ocean during this time, with southerly
flow around it pumping heat and humidity into the Mid-Atlantic.
An upper-level disturbance enhanced by convection ongoing over
the Ohio River Valley as of Sunday evening will continue moving
northeastward. The tail of this  will cross the local area
Monday afternoon and evening while gradually weakening. The
lowering heights associated with this disturbance along with a
sharp pressure trough near I-81 will bring the likelihood for
showers and thunderstorms during the afternoon and evening
hours.

Convection should initiate between noon and 1 PM along the
pressure trough, then propagate eastward fed by moderate to
strong instability (MLCAPE 2000-3000 J/kg), marginal shear (0-6
km bulk shear of 20-25 kts, though there may be near 30 kts
around 700 mb aiding cold pool prorogation and maintenance of
clusters/linear features), and eventually collisions with
bay/river breezes near I-95 by late afternoon. Downdraft CAPE
(DCAPE) is also expected to be strong, around 1000 J/kg.
Scattered damaging/downburst winds appear to be the primary
threat, though isolated large hail is possible given the strong
instability and mid-level lapse rates nearing 7 C/km. Heavy
rainfall is possible given PW increasing to 1.75-2.00 inches.
Storm motions of around 20-25 MPH and somewhat marginal warm-
cloud layer depths should preclude a more widespread flood/flash
food threat, though recent rainfall does make areas of
northern/western Virginia, eastern West Virginia and the
DC/Baltimore metro areas more vulnerable.

Convective coverage will dissipate later Monday evening and
overnight with the loss of daytime heating and as the upper-
level disturbance moves off to the east. A few showers will
remain possible into the night as the trough axis itself passes
overhead. Patchy low clouds and fog are possible late as it
will remain humid.

Eyes then turn to Tuesday.

Severe convection ongoing over the Great Plains (KS/OK) Sunday
evening will induce another Mesoscale Convective Vortex (MCV,
convectively-induced shortwave trough/mid-to-upper-level
disturbance). This shortwave will round the base of a larger
parent trough extending southward across the Great Lakes into
the Midwest, reaching the area Tuesday afternoon and evening.
Mid-level lapse rates are progged to be less steep, but
increasing low-level moisture should result in similar CAPE
values to Monday. Additionally, enhanced low-level flow ahead of
the wave by evening may eclipse 30 to 40 MPH at a few thousand
feet above ground level. This increase in low-level moisture and
shear could enhance the risk of damaging wind gusts or even an
isolated tornado threat. Another day of heavy thunderstorms will
again make the area more susceptible to potential flooding, as
well. Hail seems a bit less likely, though, given the moist
adiabatic lapse rates in the mid levels.

For temperatures, highs in the upper 80s to lower 90s are
expected, with hotter conditions Tuesday compared to Monday. Low
temperatures will generally be in the 60s to lower 70s. As
mentioned before, it will be humid (dew points around 70), so heat
indices may approach 95 F Monday afternoon, and could climb to
near 100 F in a few isolated spots briefly Tuesday afternoon.

[Rhino16]

Is wednesday looking to be the most interesting at the moment? Knowing here, that will drop real fast if I mention it.

Edit:To me, The days mentioned in the long text above seem the most interesting at the moment... I’ll go slowly through this, instead of rush and get overhyped.

[yoda]

Not even outlooked for Tuesday per new SPC OTLK for day 2... so I guess there is a disconnect there

0/5/5 for Day 1 0600 SPC OTLK

[jewell2188]

5 hours ago, yoda said:

Not even outlooked for Tuesday per new SPC OTLK for day 2... so I guess there is a disconnect there

0/5/5 for Day 1 0600 SPC OTLK

That may bode well for us after our recent run of fails lol