Jan 31 - Feb 2 Storm

[Deck Pic]

[psuhoffman]

I like this...history says this works 

[jaydreb]

Track and QPF are great.  Just a bit warm for the usual heat zones.  

[Ji]

I like this...history says this works 

Is this where the storm develops?

[jayyy]

1 minute ago, psuhoffman said:

I like this...history says this works 

If we can get the low to start bombing out here instead of just east of rehobeth, we may get lucky. Going to be awfully close with the coastal. 

[jayyy]

1 minute ago, jaydreb said:

Track and QPF are great.  Just a bit warm for the usual heat zones.  

Let the high res models iron those details out. The euro isn’t going to nail thermals this far out. If h7 passes to our south near CHO, I doubt Baltimore sees much of any mixing. 

[Ji]

If we can get the low to start bombing out here instead of just east of rehobeth, we may get lucky. Going to be awfully close with the coastal. 

Yea man need it to develop 75 miles south and let it crawl up

[psuhoffman]

7 minutes ago, Deck Pic said:

The ens mean looks a lot like the OP to me...though the trough goes negative earlier and little more sharply...also it doesn't have that annoying C PA jack...

There are some subtle differences that would help. I only see a couple members that tuck into the Delmarva like the op. The rest are at the perfect position for us just off the Delmarva coast. That would help with the mixing and getting the ccb wrapper tighter and not blowing off the the NW like the op. 

the op was a northwest outlier among the ensemble members. 

[yoda]

Just now, jayyy said:

Let the high res models iron those details out. The euro isn’t going to nail thermals this far out. If h7 passes to our south near CHO, I doubt Baltimore sees much of any mixing. 

If it passes that far south and moves eastward... we all do well... @MillvilleWx mentioned on the last page where our "Goldilocks" zone was for h7 pass

[jayyy]

Nice NE wind wrapping around and driving colder air into the back of the storm. If we do see mixing, should be relatively short lived versus the entire duration of the storm 

[psuhoffman]

3 minutes ago, Ji said:

5 minutes ago, psuhoffman said:

I like this...history says this works 

Is this where the storm develops?

that looks pretty good for us to me. 

[SnowDreamer]

2 minutes ago, psuhoffman said:

There are some subtle differences that would help. I only see a couple members that tuck into the Delmarva like the op. The rest are at the perfect position for us just off the Delmarva coast. That would help with the mixing and getting the ccb wrapper tighter and not blowing off the the NW like the op. 

 

the op was a northwest outlier among the ensemble members. 

Big L for op

[jayyy]

You Nailed the suspicion about the OP run being north of the cluster @psuhoffman.  90% of those SLP depictions would be money 

[jayyy]

Give me that one member that shows a 993 low due East of VAB. That’s all I ask. Sub 990 low as it passes by OBX.. mmm, that’s the good stuff. 

[MillvilleWx]

3 minutes ago, psuhoffman said:

I like this...history says this works 

There wasn't too much to hate for from the EPS. I loved the strong signal for a moderate WAA piece for Sunday. It's a setup where 0.5" precip can yield WSW criteria snowfall with the temps depicted. I'll be banging that drum until it happens. 

[jayyy]

Just now, MillvilleWx said:

There wasn't too much to hate for from the EPS. I loved the strong signal for a moderate WAA piece for Sunday. It's a setup where 0.5" precip can yield WSW criteria snowfall with the temps depicted. I'll be banging that drum until it happens. 

Would it bode well, especially for those folks east of the fall line, to have a nice 4-6” base of snow area wide going into round 2 as far as thermals are concerned?

[MillvilleWx]

1 minute ago, jayyy said:

Would it bode well, especially for those folks east of the fall line, to have a nice 4-6” base of snow area wide going into round 2 as far as thermals are concerned?

Possibly, but the air that corrupts the boundary layer is straight off the Atlantic, so typically that air comes in like a banshee. It's why we can get blasted and why we changeover. Blessing/curse type deal. 

[yoda]

FWIW, on the 06z NAM, snowing at DCA at 75 hours (09z SUN)

h5 map at 84... yes at end of the run and range stuff

[Ralph Wiggum]

2 hours ago, jaydreb said:

Pretty dramatic north trend tbh.  The jackpot zone on tonight’s Euro (Penn) got almost nothing in last night’s run.  

This will happen with a block moving out. Suppression was never a concern imo and seeing the 850 jump 150 N each of the past 3 runs and not slowing down that trend has us sweating bullets in the PHL forum. Let's all hold hands and pray for that 75 mile SE jump  that PSU is begging for. 

[yoda]

Just now, Ralph Wiggum said:

This will happen with a block moving out. Suppression was never a concern imo and seeing the 850 jump 150 N each of the past 3 runs and not slowing down that trend has us sweating bullets in the PHL forum. Let's all hold hands and pray for that 75 mile SE jump  that PSU is begging for. 

Or we just take the EPS...

[yoda]

Wow... that's bold of LWX to put that wording in the ZFP's already

Zone Forecast Product
National Weather Service Baltimore MD/Washington DC
338 AM EST Thu Jan 28 2021

DCZ001-VAZ054-281200-
District of Columbia-Arlington/Falls Church/Alexandria-
Including the cities of Washington, Arlington, Alexandria,
and Falls Church
339 AM EST Thu Jan 28 2021

.REST OF THE OVERNIGHT...Cloudy with a 20 percent chance of snow.
Lows in the upper 20s. North winds around 10 mph with gusts up to
25 mph.
.TODAY...Mostly cloudy in the morning, then clearing. Highs in
the mid 30s. Northwest winds 15 to 20 mph with gusts up to
40 mph.
.TONIGHT...Mostly clear in the evening, then becoming partly
cloudy. Lows in the lower 20s. Northwest winds 10 to 15 mph with
gusts up to 30 mph.
.FRIDAY...Mostly sunny. Highs in the mid 30s. Northwest winds
15 to 20 mph with gusts up to 40 mph.
.FRIDAY NIGHT...Partly cloudy in the evening, then becoming
mostly clear. Lows around 20. Northwest winds 5 to 10 mph. Gusts
up to 25 mph in the evening.
.SATURDAY...Mostly sunny. Highs in the upper 30s.
.SATURDAY NIGHT...Mostly cloudy with a 40 percent chance of snow.
Lows in the mid 20s.
.SUNDAY...Rain and snow. Highs in the mid 30s. Chance of
precipitation 80 percent.
.SUNDAY NIGHT...Snow and rain. Lows in the lower 30s. Chance of
precipitation 80 percent.
.MONDAY...Snow likely. Snow may be heavy at times. Highs in the
mid 30s. Chance of snow 70 percent.
.MONDAY NIGHT...Snow likely. Lows in the upper 20s. Chance of
snow 60 percent.

[MillvilleWx]

Quote

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
156 AM EST Thu Jan 28 2021

Valid 12Z Sun Jan 31 2021 - 12Z Thu Feb 04 2021

...Significant precipitation event likely along the central West
Coast from late weekend into early next week...

...Midwest/Ohio Valley system followed by coastal cyclogenesis to
spread a broad area of wintry weather and rain across the eastern
U.S. this weekend into next week...

...Weather Pattern Overview and Guidance/Predictability
Assessment...

Overall the latest guidance offers decent agreement and continuity
in principle for what will be an active pattern with two dominant
systems.  An eastern Pacific upper trough will bring significant
moisture into the Pacific Northwest and especially the central
West Coast from late weekend into early next week.  Then inland
progression of the trough will produce precipitation across more
of the West and by mid-late week develop a large precipitation
area over the central U.S.  This system will also bring a
pronounced cooling trend to the West and eventually Plains next
week.  The evolution heralds a significant pattern change with a
late-period eastern Pacific ridge essentially replacing what had
been a long term mean trough over the West Coast/East Pacific. 
Meanwhile guidance continues to show initial Midwest/Ohio Valley
low pressure giving way to coastal development by Mon with the
resulting system lifting northeastward with time.  An initial
supporting upper low/trough may see additional contributions from
upstream energy as this evolution occurs.  There will be potential
for meaningful (and possibly significant in some areas) snow from
the Lower Great Lakes/Ohio Valley through the northern/central
Mid-Atlantic and Northeast.  Rain will fall farther south with
highest totals likely over the southern Mid-Atlantic.

For the eastern Pacific upper trough that moves into the West and
Plains, a general blend (an operational model consensus trending
toward a model/ensemble mean mix late) works well in light of most
differences being of small enough scale as to have low
predictability for the time frame of interest.  By early next week
guidance has converged over the past day or so by way of the ECMWF
trending toward the sharper GFS on Mon followed by the GFS
trending toward the faster ECMWF progression for Tue.  Late in the
period there are some differences over where/when the strongest
bundle(s) of energy emerge over the Plains with corresponding
effects on surface low pressure.  However there is a decent signal
for a significant storm system regardless of the specifics.  An
intermediate solution seems reasonable until better defined
clustering and/or trends emerge.

For the eastern U.S./western Atlantic evolution, there is good
consensus and continuity for a Midwest upper low and trailing
trough (incorporating weak energy from upstream) to reach the East
Coast by around early Tue.  By this time and/or later additional
shortwave energy sliding down the eastern side of the upstream
ridge may feed into the upper trough, with exact influence on the
western Atlantic system yet to be determined.  For Sun-Mon recent
GFS/GEFS runs have been questionable due to being a fast extreme
with the initial Midwest system and then farther north with the
boundary on which coastal cyclogenesis occurs.  Thus the latest
forecast maintained continuity with greater emphasis on
ECMWF/CMC/UKMET solutions in this time frame.  By Tue the 18Z GFS
surface system compared better with the guidance average and
continuity.  Then by Wed the 12Z ECMWF strayed to the slow side of
the spread including the ECMWF mean--favoring a lower ECMWF weight
in the forecast by that time.   

[MillvilleWx]

I'll take this 5H forecast in Days 3-7 all the time

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif

 

Surface is pretty decent as well...

Close up of Days 4 and 5....

D4

 

D5

[yoda]

[Hurricanegiants]

Surprised it’s still at the enhanced level—seems moderate would be the case after the LWX language and the models in agreement of at least 4+?

[BristowWx]

2 minutes ago, Hurricanegiants said:

Surprised it’s still at the enhanced level—seems moderate would be the case after the LWX language and the models in agreement of at least 4+?

Today will be a big model day so plenty of time to move check marks in different directions.  Lots can happen as evident by that 100 mile north jog on the op Euro.  

[BristowWx]

Primary on 6z looks a tick south of 0z and 1mb weaker

[BristowWx]

Well it didn’t tick north. Very interesting indeed. 

[AmericanWxFreak]

That looked like another GFS sized step towards the EURO IMO 

[Weather Will]

WB 6Z GFS...