May Discobs 2025

[Weather Will]

WB 12Z FV3....anyone know how its accuracy compares to the WB 12z 3K NAM?

[EastCoast NPZ]

.23" away from an 11" month at the nearest PWS to me (probably an inch for MBY).  Can we make it tomorrow?

[WEATHER53]

Frederick does a good job of site location and crowning the middle of the field.

2nd  and 3rd  grade playoffs start this Sunday 

[BlizzardNole]

So nice out right now, partly sunny and 75

Yikes at LWX talking about tomorrow night's rain:  "Rainfall amounts of 1-2 inches are likely in the favored zone of forcing, but CAMs suggest localized totals over 4 inches are possible."

[CAPE]

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
333 PM EDT Thu May 29 2025
Day 2
Valid 12Z Fri May 30 2025 - 12Z Sat May 31 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE OHIO VALLEY AND MID ATLANTIC...

...20Z Update...

Continued increases in the forecast rainfall from the 12Z guidance
suite, sufficient instability for storms, ample upper level
forcing from a strong shortwave that rapidly turns negatively
tilted, and soil sensitivity due to recent heavy rainfall have all
worked to increase the concern for flash flooding across portions
of the Ohio Valley and Mid-Atlantic Friday and Friday night.
Generally, the convection will track from west to east...so the
portion of the Slight in Kentucky really focuses on Friday morning,
whereas the portion in northern New Jersey is primarily focused on
after midnight Friday night.

Soil sensitivity to flash flooding is high as soil moisture levels
remain well above the normal for this time of year due to rain as
recently as yesterday, and not including any shower and isolated
thunderstorm activity probable around the DMV region the afternoon
and this evening. Further, possible repeating rounds of heavy rain
on Friday interacting with the terrain and full rivers should cause
onset of flash flooding to occur sooner...closer to the rainfall
start time...in these areas, making any potential flooding more
hazardous in West Virginia. Further east, urban concerns will
increase the potential impacts from flash flooding. The storms will
also occur in the afternoon and evening, during the diurnal warmest
time of day, which will add more instability for the storms to feed
on. Given all of the above, have introduced a higher end Slight
from eastern Kentucky to the Baltimore metro. The 12Z HREF suite
shows an over 50% chance of exceeding 6-hour FFGs across the DMV.

The Slight Risk area was expanded northeast across the Philadelphia
Metro and much of northern New Jersey with this update. While the
storms will impact this region Friday evening and into the
overnight, here too recent heavy rainfall will make flash flooding
more common compared to if the soils were dry. By Friday evening
a coastal low will be rapidly forming, and so instability will be
waning as the precipitation shield evolves into more of a comma
shape, with the heaviest rains along the Delaware River on the
cold/more stable side of the low. Nevertheless, remnant instability
and long duration of rainfall will still cause widely scattered
instances of flash flooding.

[Weather Will]

WB 18Z 3K NAM and 10K RDPS came North

 

[CAPE]

Looks like some scattered storms may fire late tonight/early AM tomorrow along and east of I-95 from SW to NE. Most guidance depicts this.

 

[Ji]

I’m on the EYO board and we’ve had this discussion/argument with Rec and Parks for ages. I think we’re finally close to getting approval to let coaches work on fields to get them playable. They’ve refused up until now and they don’t work particularly hard to get them playable. 

In Loudoun…if someone tears up on a field they close it. Zero effort

[Hank Scorpio]

28 minutes ago, Ji said:

In Loudoun…if someone tears up on a field they close it. Zero effort

Yep, exactly. Last month they kicked my son's team off the field in the middle of a game. Apparently the decision to close the park happened late. Instead of just letting the little kids finish their soccer game, they insisted everyone leave the field immediately.

 

[BlizzardNole]

2 hours ago, Weather Will said:

WB 18Z 3K NAM and 10K RDPS came North

Good grief NAM -- that would be a proper mess for DC

[nw baltimore wx]

43 minutes ago, BlizzardNole said:

Good grief NAM -- that would be a proper mess for DC

I don’t need that.

[MillvilleWx]

3 hours ago, CAPE said:

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
333 PM EDT Thu May 29 2025
Day 2
Valid 12Z Fri May 30 2025 - 12Z Sat May 31 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE OHIO VALLEY AND MID ATLANTIC...

...20Z Update...

Continued increases in the forecast rainfall from the 12Z guidance
suite, sufficient instability for storms, ample upper level
forcing from a strong shortwave that rapidly turns negatively
tilted, and soil sensitivity due to recent heavy rainfall have all
worked to increase the concern for flash flooding across portions
of the Ohio Valley and Mid-Atlantic Friday and Friday night.
Generally, the convection will track from west to east...so the
portion of the Slight in Kentucky really focuses on Friday morning,
whereas the portion in northern New Jersey is primarily focused on
after midnight Friday night.

Soil sensitivity to flash flooding is high as soil moisture levels
remain well above the normal for this time of year due to rain as
recently as yesterday, and not including any shower and isolated
thunderstorm activity probable around the DMV region the afternoon
and this evening. Further, possible repeating rounds of heavy rain
on Friday interacting with the terrain and full rivers should cause
onset of flash flooding to occur sooner...closer to the rainfall
start time...in these areas, making any potential flooding more
hazardous in West Virginia. Further east, urban concerns will
increase the potential impacts from flash flooding. The storms will
also occur in the afternoon and evening, during the diurnal warmest
time of day, which will add more instability for the storms to feed
on. Given all of the above, have introduced a higher end Slight
from eastern Kentucky to the Baltimore metro. The 12Z HREF suite
shows an over 50% chance of exceeding 6-hour FFGs across the DMV.

The Slight Risk area was expanded northeast across the Philadelphia
Metro and much of northern New Jersey with this update. While the
storms will impact this region Friday evening and into the
overnight, here too recent heavy rainfall will make flash flooding
more common compared to if the soils were dry. By Friday evening
a coastal low will be rapidly forming, and so instability will be
waning as the precipitation shield evolves into more of a comma
shape, with the heaviest rains along the Delaware River on the
cold/more stable side of the low. Nevertheless, remnant instability
and long duration of rainfall will still cause widely scattered
instances of flash flooding.

Nice forecast update by my colleague. I had the Slight Risk through Eastern KY, WV, and Central MD this morning. With the latest CAMs, Philly got on board. They wanted to see one more suite before wanting the higher risk, so I backed off the Philly area on initial collaboration.  Looks like tomorrow will bring the goods 

[WxUSAF]

Flood Watch up for metro areas down to CHO for tomorrow 

[Weather Will]

Details on the Flood Watch flagged above:

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-Nelson-Albemarle-Greene-
Madison-Rappahannock-Orange-Culpeper-Fairfax-Arlington/Falls
Church/Alexandria-Stafford-Spotsylvania-King George-Northern
Fauquier-Southern Fauquier-Western Loudoun-Eastern Loudoun-
Northwest Prince William-Central and Southeast Prince
William/Manassas/Manassas Park-
831 PM EDT Thu May 29 2025

...FLOOD WATCH IN EFFECT FROM FRIDAY EVENING THROUGH LATE FRIDAY
NIGHT...

* WHAT...Flash flooding caused by excessive rainfall is possible.

* WHERE...District of Columbia, 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 Virginia, including the
  following areas, Albemarle, Arlington/Falls Church/Alexandria,
  Central and Southeast Prince William/Manassas/Manassas Park,
  Culpeper, Eastern Loudoun, Fairfax, Greene, King George, Madison,
  Nelson, Northern Fauquier, Northwest Prince William, Orange,
  Rappahannock, Southern Fauquier, Spotsylvania, Stafford and
  Western Loudoun.

* WHEN...From Friday evening through late Friday night.

* 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.

* ADDITIONAL DETAILS...
  - As a wavy slow moving frontal system tracks across the area,
    multiple rounds of showers and thunderstorms are possible.
    While initially posing a severe weather threat, a shift to a
    slow moving complex of moderate to heavy rain unfolds into
    the evening and night. Storm totals could reach 2 to 3
    inches, locally nearing 4 inches in spots.

[katabatic]

43 minutes ago, WxUSAF said:

Flood Watch up for metro areas down to CHO for tomorrow 

Interesting that it doesn't include the highlands. I'm over 9 inches for the month and streams are still quite swollen. Must think our QPF won't amount to a whole lot (altho @MillvilleWx and his crew still include us in the slight risk for excessive rainfall). 

[Weather Will]

WB 0Z HRRR...most of the rain falls later afternoon/overnight Friday.

[Weather Will]

WB 0Z 3K NAM continues to shift NW....

[Mrs.J]

So my week total is 2.27 with a monthly total of 9.47. With the potential of the rains tomorrow night will most likely go over 10” for the month. 

[yoda]

5 hours ago, katabatic said:

Interesting that it doesn't include the highlands. I'm over 9 inches for the month and streams are still quite swollen. Must think our QPF won't amount to a whole lot (altho @MillvilleWx and his crew still include us in the slight risk for excessive rainfall). 

It does now for most 

Flood Watch
National Weather Service Baltimore MD/Washington DC
317 AM EDT Fri May 30 2025

.A wavy slow moving frontal system will meander about the area on
Friday evening into the night. Anomalous moisture coupled with high
rainfall rates should increase the risk of flash flooding over
portions of this watch area.

MDZ003-VAZ025>031-503-504-507-508-WVZ050>053-055-501>506-301530-
/O.EXA.KLWX.FA.A.0008.250530T2300Z-250531T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Washington-Augusta-Rockingham-Shenandoah-Frederick VA-Page-Warren-
Clarke-Western Highland-Eastern Highland-Northern Virginia Blue
Ridge-Central Virginia Blue Ridge-Hampshire-Morgan-Berkeley-
Jefferson-Hardy-Western Grant-Eastern Grant-Western Mineral-
Eastern Mineral-Western Pendleton-Eastern Pendleton-
317 AM EDT Fri May 30 2025

...FLOOD WATCH IN EFFECT FROM THIS EVENING THROUGH LATE TONIGHT...

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

* WHERE...Portions of north central Maryland, including the
  following area, Washington, Virginia, including the following
  areas, Augusta, Central Virginia Blue Ridge, Clarke, Eastern
  Highland, Frederick VA, Northern Virginia Blue Ridge, Page,
  Rockingham, Shenandoah, Warren and Western Highland, and West
  Virginia, including the following areas, Berkeley, Eastern Grant,
  Eastern Mineral, Eastern Pendleton, Hampshire, Hardy, Jefferson,
  Morgan, Western Grant, Western Mineral and Western Pendleton.

* WHEN...From this evening 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.

* ADDITIONAL DETAILS...
  - As a slow-moving frontal system tracks across the area,
    multiple rounds of showers and thunderstorms are possible.
    While initially posing a severe weather threat, a shift to a
    slow moving complex of moderate to heavy rain unfolds into
    the evening and night. Storm totals could reach 2 to 3
    inches, locally nearing 4 inches in spots.
  - Please visit www.weather.gov/safety/flood for flood safety
    and preparedness information.

[yoda]

Flood Watch
National Weather Service Baltimore MD/Washington DC
317 AM EDT Fri May 30 2025

.A wavy slow moving frontal system will meander about the area on
Friday evening into the night. Anomalous moisture coupled with high
rainfall rates should increase the risk of flash flooding over
portions of this watch area.

DCZ001-MDZ004>006-008-011-013-014-016>018-503>508-VAZ036>040-050-051-
053>057-501-502-505-506-526-527-301530-
/O.CON.KLWX.FA.A.0008.250530T2300Z-250531T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
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-Nelson-Albemarle-Greene-
Madison-Rappahannock-Orange-Culpeper-Fairfax-Arlington/Falls
Church/Alexandria-Stafford-Spotsylvania-King George-Northern
Fauquier-Southern Fauquier-Western Loudoun-Eastern Loudoun-
Northwest Prince William-Central and Southeast Prince
William/Manassas/Manassas Park-
317 AM EDT Fri May 30 2025

...FLOOD WATCH REMAINS IN EFFECT FROM THIS EVENING THROUGH LATE
TONIGHT...

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

* WHERE...Portions of DC, including the following , District of
  Columbia, 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
  Virginia, including the following areas, Albemarle,
  Arlington/Falls Church/Alexandria, Central and Southeast Prince
  William/Manassas/Manassas Park, Culpeper, Eastern Loudoun,
  Fairfax, Greene, King George, Madison, Nelson, Northern Fauquier,
  Northwest Prince William, Orange, Rappahannock, Southern Fauquier,
  Spotsylvania, Stafford and Western Loudoun.

* WHEN...From this evening 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.

* ADDITIONAL DETAILS...
  - As a slow-moving frontal system tracks across the area,
    multiple rounds of showers and thunderstorms are possible.
    While initially posing a severe weather threat, a shift to a
    slow moving complex of moderate to heavy rain unfolds into
    the evening and night. Storm totals could reach 2 to 3
    inches, locally nearing 4 inches in spots.
  - Please visit www.weather.gov/safety/flood for flood safety
    and preparedness information.

[yoda]

Also, zones now say sunny and hot with highs around 90 for next Wednesday and Thursday

[dailylurker]

It's been pouring early this morning here in the lowlands. Getting primed for the flooding tonight. 

[frd]

12 hours ago, CAPE said:

Looks like some scattered storms may fire late tonight/early AM tomorrow along and east of I-95 from SW to NE. Most guidance depicts this.

 

Yep, getting hit currently. Tropical downpour, extremely heavy rain.   

[North Balti Zen]

It rained between midnight and 5 in hunt valley area I think / there’s puddles in the parking lots over here by the light rail