FXUS61 KLWX 261347

AFDLWX



Area Forecast Discussion

National Weather Service Baltimore MD/Washington DC

947 AM EDT Thu Jun 26 2025



.SYNOPSIS...

A ridge of high pressure overhead will maintain hot conditions 

through this evening. Daily chances for showers and 

thunderstorms will increase through the end of the week. A weak 

frontal boundary will slowly drift southward in time before 

stalling nearby through Friday. This system gradually lifts

northward away from the area this weekend. A stronger cold 

front may cross the region by early next week.



&&



.NEAR TERM /THROUGH TONIGHT/...

Current observations across the region show a cooler start to

the day today. This is likely, at least partially, due to the

convection yesterday really working over the atmosphere.

Temperatures this morning are running a few degrees cooler, and

dew points are also a couple degrees cooler than this time

yesterday. Mostly sunny skies being observed for now, but expect

that to change quickly by mid-late morning. The 12z IAD RAOB

shows a significantly more moist column this morning, with PWATS

already exceeding two inches. A weak cap is in place, with CIN

values around 100 J/kg in the mixed layer, but expect that to

quickly mix out as we warm into the low 90s by around noon. A

robust cu field will likely develop as a result, with convective

initiation strictly from the diurnal heating and orographic

influences happening perhaps around noon or shortly thereafter.

This would be most likely for areas further west to start, with

areas further east initiating an hour or two later along any

remnant outflow boundaries and/or bay/river breezes.

Additionally, a stalled surface boundary across northern 

Pennsylvania/Ohio is expected to sag southward in time today,

eventually pushing into our area later this evening. As this 

occurs, enhanced frontal lift coupled with perturbations in the 

mid/upper atmosphere will favor an increasing risk of showers 

and thunderstorms. With afternoon high temperatures rising into 

the low/mid 90s and continued humid conditions, instability 

profiles remain quite robust. Forecast surface-based CAPE values

rise into the 2,500 to 3,500 J/kg range, but with rather weak 

deep-layer shear (averaging around 10 knots). This lack of 

vertical shear suggests disorganized convection while focusing 

more intently on mesoscale boundaries (i.e., river and bay 

breezes, as well as old convective outflows/cold pools).

Compared to yesterday, there are a few notable differences that

suggest that the high-end wind gust potential should be lower

today. Surface to min Theta-e values are substantially lower

today than this time yesterday, and favor a more isolated 

damaging wind threat. Secondly, as previously mentioned, there

is a lot more moisture in the column today, thus we have a lot

less DCAPE to work with (albeit still conducive to some severe

gusts). Lastly, mid-level lapse rates are a bit weaker than

yesterday as well. So, in short, thinking storms may have a

slightly harder time getting well established and extremely

tall like we saw yesterday. However, do think there will be a

few that are able to overcome these issues and we will probably

see at least a few damaging wind gusts. Additionally, with wet

ground from storms yesterday and again today, it may not take

severe winds to blow down trees, so would expect to see a good

bit of that today as well. Lastly on the thunderstorm threat,

storms today will again be prolific lightning producers given

the level of instability. 



As was mentioned earlier, with precipitable water values around

2 inches, slow cell motions, and the potential of repeat 

convection firing along erratic outflows, flash flooding is 

possible this afternoon/evening. The Weather Prediction Center 

has painted a Slight risk for flash flooding across areas east 

of the Catoctinsand Blue Ridge. The overnight HREF actually has

some highlights along the I-95 corridor for potential of 3"+ of

rainfall in 3 hours. This is rather concerning, so a Flood Watch

is being considered at this time for this area. Once 12z

guidance comes in, a final decision can be made on that a little

later this morning prior to CI. 



Most high-resolution models depict activity waning after 

midnight so any severe/flood threat should wane at that point.



Besides the convective threats, continued above average

temperatures and high humidity levels will carry heat indices

into the 102 to 107 degree range. Furthermore, Heat Advisories

extend over a bulk of the area outside the mountains from 11 AM

until 7 PM this evening. Continue to find ways to stay cool in

the heat by taking plenty of breaks from the outdoors, staying 

hydrated, and wearing light clothing. Heading into the overnight

hours, the influence of rain-cooled air should help carry lows

into the upper 60s to low 70s (low/mid 60s in the mountains).



&&



.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...

While the placement of the frontal zone is uncertain and likely

re-positioned by convective-scale processes, this system should

be in the vicinity of the Mid-Atlantic region on Friday. Not

only will this carry an additional risk for showers and

thunderstorms, but also comes with a challenging temperature

forecast. For those in the cool sector to the north, highs in

the mid/upper 70s are likely. Off to the south, the warm/moist

sector will support temperatures well into the 80s to near 90

degrees. The current forecast calls for this separation of air

masses to be between I-70 and I-66. 



There should be a particular focus for convection in the 

vicinity of this frontal zone where lift will be augmented. 

Along and south of this front will yield a severe weather 

component to the storms where instability is maximized.

Additionally, well above average columnal moisture profiles

favor further instances of flooding potential. It is difficult

to say where this will occur, but the usual focuses would be in

the urban corridors and regions hit by previous days of heavy

rainfall. Depending on how quickly instability is exhausted,

some of the convection could fester into the overnight hours on

Friday.



With mid/upper height changes being somewhat neutral, it 

remains to be seen how much northward progress this boundary 

makes on Saturday. This system could easily linger right near 

the Mason-Dixon Line which would maintain a more unsettled 

pattern during the first half of the weekend. The expectation is

for this boundary to drift northward in time on Saturday which

will help usher highs back into the upper 80s to low 90s.

Further, convection would be driven more heavily by instability

versus along any particular frontal boundaries. But as

mentioned, there is plenty of uncertainty in how this all plays

out. Will see Saturday night's lows be a tad milder than

previous nights with readings in the upper 60s to mid 70s.



&&



.LONG TERM /SUNDAY THROUGH WEDNESDAY/...

The Summertime convection threat continues each day Sunday 

through Tuesday, mainly in the afternoon and evening hours when 

it is the warmest. High temperatures will reach the lower to 

middle 90s each afternoon. A strong upper trough and associated 

surface cold front is expected to cross the area on Tuesday. 

This could lead to an active afternoon and evening with multiple

rounds of convection and/or severe thunderstorms. High pressure

builds in the wake by the middle of next week which favors a

return to drier weather.



&&



.AVIATION /13Z THURSDAY THROUGH MONDAY/...

With convection in the forecast through the remainder of the

work week and into the first half of the weekend, periods of

restrictions are looking likely at times. Otherwise, VFR

conditions should be commonplaceoutside of these convective

episodes. For this afternoon/evening, remain confident enough in

thunderstorm development to have a 3 to 4 hour period of TSRA

restrictions roughly between 20-00Z. As some of this may linger

after dark, have maintained the PROB30 groups into subsequent

hours as inherited by previous shifts.



As a frontal zone drifts southward across the area, winds turn

more easterly in nature on Friday. Eventually this boundary does

return northward as a warm front which would bring a return to

south-southwesterlies at some point on Saturday. And as

mentioned, restrictions are possible given a decent chance for

thunderstorms each afternoon/evening.



VFR conditions at all terminals Sunday through Monday night. At

times of convection, we could see brief MVFR visibility and/or 

ceilings. Winds will be light and variable, except higher gusts 

in strong thunderstorms.



&&



.MARINE...

While gradients remain weak enough to keep the waterways free of

Small Craft Advisories, the threat of convection will make for

hazardous boating conditions at times through at least Saturday.

It is difficult to say which day will be the most active in

terms of thunderstorm development, but the degree of continued

heat and humidity should maintain a daily 30-60 percent chance

of storms each afternoon/evening. As usual, frequent lightning

is possible in any such storm, with the stronger cells likely

requiring Special Marine Warnings.



No marine hazards Sunday through Monday night. If thunderstorms

move out over the waters, then Special Marine Warnings may be 

warranted. Winds light and variable through the period, except 

higher gusts in strong thunderstorms.



&&



.TIDES/COASTAL FLOODING...

Tidal anomalies will remain slightly elevated through the next

several high tide cycles. This will keep water levels slightly 

elevated for the more sensitive tidal sites. At this point, only

Annapolis is slated to reach Action stage during the next 

couple of astronomical high tides.



&&



.CLIMATE...

Here are some daily high temperature records on June 26, 2025:



A '+' sign indicates multiple years currently hold that record. 



                 ***THURSDAY, JUNE 26TH, 2025***

LOCATION                   RECORD HIGH (YEAR)  RECORD WARM LOW (YEAR)

Washington-National (DCA)     101F (1952)          77F (1952)+  

Washington-Dulles (IAD)        99F (2024)          72F (2023)+  

Baltimore (BWI)                99F (2024)+         80F (1952)

Baltimore Inner Harbor (DMH)  104F (1998)          83F (1952)

Martinsburg (MRB)             102F (1943)          75F (1949)      

Charlottesville (CHO)          99F (1998)          78F (1952)

Annapolis (NAK)                98F (1998)+         81F (1952)

Hagerstown (HGR)               98F (1954)+         75F (1952)



&&



.LWX WATCHES/WARNINGS/ADVISORIES...

DC...Heat Advisory until 7 PM EDT this evening for DCZ001.

MD...Heat Advisory until 7 PM EDT this evening for MDZ003>006-008-

     011-013-014-016>018-502>508.

VA...Heat Advisory until 7 PM EDT this evening for VAZ026>031-

     036>040-050-051-053>057-501-502-505-506-526-527.

WV...Heat Advisory until 7 PM EDT this evening for WVZ050>053-055-

     502-504.

MARINE...Heat Advisory until 7 PM EDT this evening for ANZ530.



&&



$$



SYNOPSIS...BRO

NEAR TERM...CJL/BRO

SHORT TERM...BRO

LONG TERM...BRO/KLW

AVIATION...BRO/KLW

MARINE...BRO/KLW

TIDES/COASTAL FLOODING...LWX

CLIMATE...LWX

