July Discobs 2025

[JenkinsJinkies]

If the air is this soupy then the front will deliver an epic deluge.

[mappy]

79/77 at 8am. 

[wxdude64]

Second day in a row with a record 'warm minimum'. Old record for date was 69 degrees from 1982 and 2004, new record is 70.0 degrees. Soupy out there, currently 71.2/69.6 at 8 am. 

[frd]

81/76 heat index 87, at least that is not too bad currently. Time to mow ahead of the epic rains. 

However, as mentioned by others, the overnight lows and overnight dewpoints are nuts !  

[BlizzardNole]

Just got back in after watering and man is it hot already.  At least no more mowing needed as the grass is completely dormant.  Looking forward to spending hours out on the deck starting this weekend!

[IronTy]

Yeah it's gross out.  Front please move through on time.  

[87storms]

Catoctin Creek is running pretty low again. This area could use a deluge at this point, but the models aren’t showing a whole lot from this event for the rain shadow zones. Hopefully we can at least get a line of cells to move through.

[Subtropics]

Anyone know if this will be the clear #1 for highest average dew point / humidity in dc on record?

Seems like half the days were 75+ for much of the day - even in these parts that seems unusual?


.

[Kmlwx]

1 minute ago, Subtropics said:

Anyone know if this will be the clear #1 for highest average dew point / humidity in dc on record?

Seems like half the days were 75+ for much of the day - even in these parts that seems unusual?


.

I know a lot of our days in past summers, the dewpoint gets ticked downwards a bit by downsloping winds. Seems perhaps that has been largely missing this year? 

[WxUSAF]

3k NAM starts storms by 12-1pm

[yoda]

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
939 AM EDT Thu Jul 31 2025

.SYNOPSIS...
A cold front will slowly move across the mid-Atlantic today
through Friday. Strong high pressure will build into the area
over the weekend, bringing below normal temperatures and
humidity. High pressure weakens into next week while the next
front is expected to slowly approaches from the south. Rain
chances return by the middle of next week.

&&

.NEAR TERM /THROUGH FRIDAY/...
Excessively humid conditions are being observed across the
region with dew points well into the 70s to near 80 and PW in
excess of 2 inches (even 70+ Tds over the higher terrain). This
will fuel thunderstorms with very heavy rain beginning in a few
hours (roughly midday onward).

A cold front will sag south into our region today. A strong
shortwave trough will move over our area this afternoon and
evening. A persistent southerly flow will provide deep tropical
moisture to help fuel numerous heavy showers and strong to
severe thunderstorms this afternoon and evening. Dewpoint
temperatures in the low to mid 70s will result in revealing
PWATs of 2.2 to 2.3 inches. One final day of hot and humid
conditions today with the developing convection. Highs are
forecast to be in the upper 80s to low 90s, with peak heat
indices between 95-105.

[WxUSAF]

Mesoanalysis has CAPE >4000 around BWI

[yoda]

Initiation near Bel Air

[yoda]

85/78 at DCA at 10am... yucky

[Weather Will]

Latest NWS statement on flood watch

District of Columbia-Frederick MD-Carroll-Northern Baltimore-
Cecil-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-Fairfax-Arlington/Falls
Church/Alexandria-Northern Fauquier-Southern Fauquier-Western
Loudoun-Eastern Loudoun-Northwest Prince William-Central and
Southeast Prince William/Manassas/Manassas Park-
1035 AM EDT Thu Jul 31 2025

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

* WHAT...Flash flooding caused by excessive rainfall continues to be
  possible.

* WHERE...The District of Columbia, portions of Maryland, including
  the following areas, Anne Arundel, Calvert, Carroll, Cecil,
  Central and Southeast Howard, Central and Southeast Montgomery,
  Charles, Frederick MD, Northern Baltimore, Northwest Harford,
  Northwest Howard, Northwest Montgomery, Prince Georges, Southeast
  Harford, Southern Baltimore and St. Marys, and northern Virginia,
  including the following areas, Arlington/Falls Church/Alexandria,
  Central and Southeast Prince William/Manassas/Manassas Park,
  Eastern Loudoun, Fairfax, Northern Fauquier, Northwest Prince
  William, Southern Fauquier and Western Loudoun.

* WHEN...From 2 PM EDT this afternoon through late tonight.

* IMPACTS...Excessive runoff may result in flooding of rivers,
  creeks, streams, and other low-lying and flood-prone locations.
  Flooding may occur in poor drainage and urban areas. Extensive
  street flooding and flooding of creeks and rivers are possible.

* ADDITIONAL DETAILS...
  - Significant flash flooding is possible. Numerous showers and
    thunderstorms will develop and move across the area this
    afternoon into this evening. Thunderstorms will be capable of
    producing very heavy rain, with rainfall rates of 1 to 2
    inches in 30 minutes. Widespread rainfall amounts of 1 to 2
    inches are expected. Some areas could experience multiple
    rounds of thunderstorms, with higher rainfall amounts of 4 to
    6 inches possible. This could result in numerous instances of
    flash flooding. Showers and thunderstorms will begin early
    this afternoon, and the heaviest rainfall is most likely from
    3 PM to 8 PM.
  - Please visit www.weather.gov/safety/flood for flood safety
    and preparedness information.

 

[mappy]

45 minutes ago, WxUSAF said:

3k NAM starts storms by 12-1pm

Stuffing popping up in northern Balt Co. 

[BlizzardNole]

This makes you wonder what it feels like when places have hit rare super high dew points of 88 or 90.  

[SomeguyfromTakomaPark]

1 hour ago, Subtropics said:

Anyone know if this will be the clear #1 for highest average dew point / humidity in dc on record?

Seems like half the days were 75+ for much of the day - even in these parts that seems unusual?


.

Yeah been saying this all July, I can’t remember this many days of 75+ dews.  Normally that’s a high end type humidity day not every day of July. 

[high risk]

58 minutes ago, WxUSAF said:

3k NAM starts storms by 12-1pm

  The HRRR is an outlier with focusing on the period around dinner time.  Multiple other CAMs  say that the period of interest for a good part of the area is much earlier.    I recommend looking at the experimental RRFS on Pivotal   It really crushes the DC/PG/Howard crew fairly early.

[JenkinsJinkies]

24 minutes ago, BlizzardNole said:

This makes you wonder what it feels like when places have hit rare super high dew points of 88 or 90.  

It’s called lethal wet bulb for a reason

[yoda]

https://www.wpc.ncep.noaa.gov/metwatch/metwatch_mpd_multi.php?md=0832&yr=2025

Mesoscale Precipitation Discussion 0832
NWS Weather Prediction Center College Park MD
1101 AM EDT Thu Jul 31 2025

Areas affected...Mid-Atlantic...

Concerning...Heavy rainfall...Flash flooding likely

Valid 311500Z - 312100Z

SUMMARY...Potential for slow moving, highly efficient
thunderstorms with localized 2-3"/hr rates possible.  Storm
interactions may allow for localized totals of 2-4" totals and
likely to induce flash flooding conditions by 21z.

DISCUSSION...Surface analysis and visible GOES-E imagery shows a
well defined stationary front within the Long Island sound
intersecting to a surface low in the Delaware Valley before
entering the terrain through the Lehigh Valley into south-central
PA.  A secondary surface wave near MDT/THV has a sharpening Lee
Trough extending southward along the lee of the Blue Ridge toward
Roanoke, VA and points south.  Between the boundaries through the
Mid-Atlantic, very moist and building instability can be seen with
sfc Tds in the mid-70s with isolated low 80s dotted throughout the
area.  Weak southerly, confluent flow through 700-500mb is noted
in CIRA LPW layers with enhanced moisture which totals over 2"
(KIAD already at 2.16" at 12z) and will be increasing toward
2.25+" into the early afternoon.  MLCAPE values have reached 2000
J/kg with weak capping noted and visible imagery shows expanding
Cu field across much of the area, with some weak vertical
development along major ridge lines of E PA, or near the
stationary front/outflow boundary intersections across N NJ.

Aloft, WV shows a very strong jet streak across the St.Lawrence
River Valley with broad right entrance ascent pattern across much
of the Upper OH valley through central NY into the Interior of New
England.  The convectively enhanced shortwave continues to
shear/elongate from SSW to NNE with upstream core over E OH and
into confluent flow will continue, along with the right entrance
ascent provide ample DPVA and ascent profiles throughout the
Mid-Atlantic.  Bulk shear is greater near and north of the surface
front likely to result in greater cell organization but is further
distanced from deepest moisture/highest Theta-E near the
Chesapeake Bay into SE PA.  As such, there is likely to be
difference in convective activity/manner across the area.  Weak
convergence along the lee trough/Blue Ridge is likely to expand
areas of convection westward with time as well across NW VA.

South of the Lehigh Valley, 12z guidance is increasing confidence
in initial convective development through the 15-16z time frame. 
Initial thunderstorms will be very slow moving, but have
stronger/broader updrafts with 14-15Kft of warm cloud layer for
highly efficient rainfall production.  While inflow will be weak,
it is likely to pull multiple broad columns of that 2-2.25" Total
PWat air to support 2-3"/hr rates by 18z given very slow cell
motions (slower further south).  Storm scale interaction/cold pool
generation is likely to be the dominant mode of propagation, so
interactions/collisions/mergers are possible and may result in
increased duration to support localized 3-4" totals.  

The area remains saturated with 0-40cm soil ratios over 50-60%
which is in the 70-80th percentile, combine that with proximity to
large urban centers with impermeable surfaces; the shear rates are
likely to overwhelm ground conditions quickly and result in flash
flooding conditions; a localized considerable incident of flooding
is possible as well.  

Gallina

ATTN...WFO...BGM...CTP...LWX...OKX...PHI...

ATTN...RFC...RHA...TAR...NWC...

 

[frd]

90/77 Heat index 103   Enough, please stop !

Outside landscaping this morning and the thing that bothers me the most is the constant sweat pouring down my face.  

[RDM]

1 hour ago, BlizzardNole said:

This makes you wonder what it feels like when places have hit rare super high dew points of 88 or 90.  

It's not much fun.  During monsoon seasons I experienced in India, Thailand and Japan involved extreme dew points.  When going from a cooled/conditioned environment into the soupy air the condensation on any non-fabric surface is immediate.  Glasses instantly fog over - cell phones leave a wet spot in your pants pockets and mold can grow overnight on shoes that never fully dry out.  It's a daily grind at times.    

[Interstate]

I have a storm just to the east of me here in 21057... I am getting a little rain from it.

[pazzo83]

this humidity is completely insane.

[yoda]

Nothing really initiating in N VA yet... a couple showers/storm N of DC metro... Baltimore metro already has numerous storms

[WxWatcher007]

Yeah, it’s pretty humid out here  

[George BM]

91/77 at IAD.

[mappy]

Radar got busy real quick up here. Can hear the rumbling from the Bel Air storm. 

[dailylurker]

I've spent the past several hours putting up a support system for my cannabis plants. It's been brutal as hell. The plants are huge and I'm on a ladder in the blazing sun. Two down, two to go. I'm trying to beat the heavy rains. I don't want these large ladies getting bet up this evening.