August Medium/ Long Range

[Weather Will]

Latest WB EPS weekly temps for August.  Entire month forecasted drier than normal.

[Eskimo Joe]

Entirely possible the rest of the summer is at or below normal. We can save our heat waves for Christmas!

[frd]

On 7/28/2025 at 5:25 PM, Weather Will said:

Latest WB EPS weekly temps for August.  Entire month forecasted drier than normal.

I forget where but I thought I read that evidence is growing for yet another heatwave the week of August 11th to the 18th. Have you seen anything about that? 

[Weather Will]

2 hours ago, frd said:

I forget where but I thought I read that evidence is growing for yet another heatwave the week of August 11th to the 18th. Have you seen anything about that? 

WB latest weeklies for mid August to mid September forecast above normal temps/ drier than normal conditions for central zones mid August to mid September.

[WxUSAF]

Euro and GGEM has a very wet end of the week. Gfs says “what rain”?

[Maestrobjwa]

4 hours ago, WxUSAF said:

Euro and GGEM has a very wet end of the week. Gfs says “what rain”?

I hope the gfs is right. I'll be reenacting something outside on grass next Saturday...

[CAPE]

9 hours ago, WxUSAF said:

Euro and GGEM has a very wet end of the week. Gfs says “what rain”?

12z GFS looks a bit more interesting with low pressure off the SE coast that gets squeezed northwestward as a sprawling area of HP in eastern Canada shifts southeastward into the Gulf of Maine. Verbatim it's a glancing blow for southeastern parts of our region.

[Eskimo Joe]

I finally get a week off to go to the beach and the forecast jut tanks. Lovely.

[Weather Will]

WB 18Z NBM.  Rain chances low through Wed.  Chances increase Th. Ann's Friday.

[Weather Will]

WB OZ GFS and EURO now both dry for the week ahead.

[Eskimo Joe]

5 hours ago, Weather Will said:

WB OZ GFS and EURO now both dry for the week ahead.

Good. Keep lower Delmarva dry.

[stormy]

Euro Weeklies and GEFS Extended in general agreement for August precip.     Dry, D.C. east, wet west of D.C. especially up the spine of Apps.

Heat Dome likes the 4 corners ( better than Texas, east),   with a slight semblance of troughiness for the east.    

[Weather Will]

WB 12Z GFS and EURO precip. through Day 7.  EURO can't make up its mind....

[stormy]

17 minutes ago, Weather Will said:

WB 12Z GFS and EURO precip. through Day 7.  EURO can't make up its mind....

The Euro has sucked up some GGEM juice!

[Weather Will]

6 minutes ago, stormy said:

The Euro has sucked up some GGEM juice!

WB 12Z Can. At Day 7...

[CAPE]

4 hours ago, Weather Will said:

WB 12Z GFS and EURO precip. through Day 7.  EURO can't make up its mind....

Do you ever look at the ensemble guidance? It's inherently less volatile run to run in the LR, and gives us an indication of forecast uncertainty. A single deterministic model cannot do this.

[CAPE]

12z ens guidance- EPS and GEPS depict the more significant precip chances for central/western VA late week, with lesser amounts possible for locations further north/east. The GEFS keeps all notable precip southeast of our region.

[Weather Will]

2 hours ago, CAPE said:

Do you ever look at the ensemble guidance? It's inherently less volatile run to run in the LR, and gives us an indication of forecast uncertainty. A single deterministic model cannot do this.

I do look at ensembles, and maybe you are correct, but I am still annoyed at how good the ensembles looked for a big February snowstorm and everything went poof.  Guess that is the way it goes.  WB 18Z Euro is wet again west of the bay, and still raining at end of the run on Friday. WB 18Z EURO ensembles are also wetter through Friday afternoon compared to 12Z.

[Jrlg1181]

Looking at these 0Z models,  except the GFS... That would be problematic to say the least.. A repeat of last September simply wouldn't be good.. Except for Debby in August ( some creeks were dry again 3 weeks later ) - the major drought kept widespread problems along the main rivers to a minimum although some local spots had significant smaller creek flood damage....

[Weather Will]

WB 12z runs thru Day 6: GFS, Can. and  EURO.  EURO would have people screaming if this was winter....another example of it folding is occurring.

[Weather Will]

WB 12Z Ensembles thru Day 6.

[Weather Will]

Afternoon discussion from Sterling NWS summarizes the uncertainty with the end of the week outlook...

Plenty of uncertainty remains in the extended period in regards to
the placement and timing of a slow moving (nearly cutoff) upper
level trough from the west and an area of low pressure working along
the southeast U.S coast. These two features combined with the
interaction of broad wedging high pressure off the northern New
England coast/southern Canadian Maritimes will influence how much
deep tropical moisture is funneling into the region.

As of now, have went ahead and increased shower and thunderstorm
chances (PoPs 30-50 percent), especially during the afternoon and
evening hours Wednesday through Friday as onshore flow increases
with the low pressure system just off the NC coast and an inverted
trough nearby. Have backed off the rain chances for the upcoming
weekend to around 15 to 30 percent. The 12z GFS/GEFS favors low
pressure coming up along the coastal Carolinas and into eastern
VA/Delmarva Friday into Saturday leading to increased shower and
thunderstorm chances during this time. The 12z ECMWF/EPS favors more
of the Thursday through Friday timeframe for tropical moisture as a
strong baroclinic zone sets up over the region. The ECMWF/EPS is
also more aggressive with high pressure wedging itself back into the
area for the upcoming weekend allowing precipitation chances to
decrease. The 12z Canadian is a blend of the two aforementioned
solutions above along with central guidance. It still carries heavy
probability of precipitation Thursday into Friday while lingering it
into the weekend.

With all said, specifics surrounding rain chances, amounts, and wind
will continue to remain uncertain until models can get a better grip
on the features at play. Increased onshore flow will remain leading
to seasonably normal to slightly below normal temperatures and
increased cloudiness throughout the extended period. Expect highs in
the 70s and 80s with lows in the 50s and 60s.

 

 

[stormy]

The Euro and GEM have caved to the dry GFS for the end of the week. The GFS has been dry consistently while the Euro has been wet consistently.  

This is a big win for the GFS and a kick in the groin to the Euro.

[Weather Will]

6 minutes ago, stormy said:

The Euro and GEM have caved to the dry GFS for the end of the week. The GFS has been dry consistently while the Euro has been wet consistently.  

This is a big win for the GFS and a kick in the groin to the Euro.

Yes, big win for GFS this week, but the EURO is trying to bring up a disturbance late Sunday into Monday now.  Will add ensemble when it is out.

[stormy]

42 minutes ago, Weather Will said:

Yes, big win for GFS this week, but the EURO is trying to bring up a disturbance late Sunday into Monday now.  Will add ensemble when it is out.

Please do Will.  I always look forward to your Updates!!

[stormy]

The models have dried for Wednesday and Thursday and Sterling has went wetter for Staunton.

https://forecast.weather.gov/MapClick.php?lon=-79.05445863492788&lat=38.16380555335593

 

[Weather Will]

WB 12Z EPS for late in the weekend, wetter than 0Z.  Note: great write up in the tropical thread on this by 007.