Mid to Long Range Discussion ~ 2023

[Upstate Tiger]

What a nice Easter weekend in store for us in the Carolinas...

LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 300 AM EDT Monday: The alluded frontal boundary will sweep
into the CFWA on Thursday. Most model guidance keeps a narrow band
of showers and storms along the boundary as it pushes through
the area. Some scattered showers and storms may develop just
ahead of the main boundary, but the main focus will be along
the frontal axis. With a slight uptick in shear parameters and
global models/NAM depicting decent SBCAPE (750-1500 J/kg) values
ahead of the boundary, most should expect some form of organized
convection Thursday afternoon/evening, with a low-end severe
threat, but confidence remains low on this development. Either way,
temperatures will remain 10-15 degrees above-normal for highs on
Thursday as most of the CFWA will settle under a stout warm sector.

Major changes will be underway behind the front Thursday night
as a strong surface high travels across the Central Plains and
Midwest Thursday and into the OH Valley Thursday night. As the
surface high sets up shop over the Mid-Atlantic early Friday, model
guidance continue to place the CFWA under a hybrid CAD. With the
flow aloft oriented from the southwest to northeast, deep moisture
will continue to traverse over the CAD dome. Expect temperatures
to dropoff nearly 20 degrees for highs on Friday compared to
Thursday. The frontal boundary will stall south of the area,
but moist upglide should keep PoPs elevated on Friday and through
much of the weekend. By the weekend, the surface high should slip
offshore the Mid-Atlantic coast and transition into more of an
in-situ wedge, locking in the cold air through at least Sunday with
temperatures remaining 10-15 degrees below-normal over the weekend
for highs, with the potential for values to be even lower. Signs
of CAD erosion doesn`t appear in model guidance until late Sunday
into Monday as a shortwave trough pushes in from the Deep South
and a surface wave travels underneath before deepening off the
Southeast Coast during this timeframe. In this case, expect for
a very cloudy and gloomy end to the week with well below-normal
temperatures and continuous cloud cover through the end of the
period following the fropa late Thursday.

[yotaman]

1 hour ago, Upstate Tiger said:

What a nice Easter weekend in store for us in the Carolinas...

LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 300 AM EDT Monday: The alluded frontal boundary will sweep
into the CFWA on Thursday. Most model guidance keeps a narrow band
of showers and storms along the boundary as it pushes through
the area. Some scattered showers and storms may develop just
ahead of the main boundary, but the main focus will be along
the frontal axis. With a slight uptick in shear parameters and
global models/NAM depicting decent SBCAPE (750-1500 J/kg) values
ahead of the boundary, most should expect some form of organized
convection Thursday afternoon/evening, with a low-end severe
threat, but confidence remains low on this development. Either way,
temperatures will remain 10-15 degrees above-normal for highs on
Thursday as most of the CFWA will settle under a stout warm sector.

Major changes will be underway behind the front Thursday night
as a strong surface high travels across the Central Plains and
Midwest Thursday and into the OH Valley Thursday night. As the
surface high sets up shop over the Mid-Atlantic early Friday, model
guidance continue to place the CFWA under a hybrid CAD. With the
flow aloft oriented from the southwest to northeast, deep moisture
will continue to traverse over the CAD dome. Expect temperatures
to dropoff nearly 20 degrees for highs on Friday compared to
Thursday. The frontal boundary will stall south of the area,
but moist upglide should keep PoPs elevated on Friday and through
much of the weekend. By the weekend, the surface high should slip
offshore the Mid-Atlantic coast and transition into more of an
in-situ wedge, locking in the cold air through at least Sunday with
temperatures remaining 10-15 degrees below-normal over the weekend
for highs, with the potential for values to be even lower. Signs
of CAD erosion doesn`t appear in model guidance until late Sunday
into Monday as a shortwave trough pushes in from the Deep South
and a surface wave travels underneath before deepening off the
Southeast Coast during this timeframe. In this case, expect for
a very cloudy and gloomy end to the week with well below-normal
temperatures and continuous cloud cover through the end of the
period following the fropa late Thursday.

Sounds wonderful.

[GaWx]

 The GFS suite the last few runs has continued to say "What cold? The suite had for days been showing a cold shot (30s lows much of the SE) for 4/12-13. Now that period on it is near normal at the coldest.

[olafminesaw]

11 minutes ago, GaWx said:

 The GFS suite the last few runs has continued to say "What cold? The suite had for days been showing a cold shot (30s lows much of the SE) for 4/12-13. Now that period on it is near normal at the coldest.

And we're at that sweet spot in the year where slightly below and slightly above average are fantastic, and well above or below are tolerable (barring a wedgy drizzle-fest)

[wncsnow]

7 minutes ago, olafminesaw said:

And we're at that sweet spot in the year where slightly below and slightly above average are fantastic, and well above or below are tolerable (barring a wedgy drizzle-fest)

Lots of cool wedge drizzle-fests are on the way it seems. I expect many places in western nc won't get out of the 40s all weekend.

[olafminesaw]

14 hours ago, wncsnow said:

Lots of cool wedge drizzle-fests are on the way it seems. I expect many places in western nc won't get out of the 40s all weekend.

At least now Easter Sunday high pressure is starting to move in, so should be clearing up throughout the day

[olafminesaw]

About to get soggy! So much for drought concerns

[JoshM]

Let's get NAM'd one more time!

[olafminesaw]

23 minutes ago, JoshM said:

Let's get NAM'd one more time!

Lol!

[NorthHillsWx]

Latest NAM has 1-3” of snow Saturday night for most of central NC 

[olafminesaw]

42 minutes ago, NorthHillsWx said:

Latest NAM has 1-3” of snow Saturday night for most of central NC 

 

[eyewall]

It isn't there on the 12z

[JoshM]

Planning to drive to Mount Mitchell park on Saturday, maybe I'll get a mercy flake of snow. Will share any photos

[WinstonSalemArlington]

May Day, May Day!

 

[marsman]

Couldn't find this anywhere, but heads up, KRAX is down through 04/28:

 

 

[StantonParkHoya]

6 hours ago, WinstonSalemArlington said:

May Day, May Day!

 

Awesome! Maybe we can hold onto the 70s a few more weeks

[olafminesaw]

6 hours ago, marsman said:

Couldn't find this anywhere, but heads up, KRAX is down through 04/28:

 

 

That's kinda stupid at like peak severe season. Not that there's anything significant on the horizon thankfully. 

 

[eyewall]

11 hours ago, olafminesaw said:

That's kinda stupid at like peak severe season. Not that there's anything significant on the horizon thankfully. 

 

Yeah apparently it was not a decision made by the local office but higher up.

[GaWx]

Early to mid next week is looking pleasantly cool at night and mild during the afternoons with very low RH. The AO is progged to go below -3 4/19-20, the lowest since December. Also, late next week the PNA is forecasted to get to its highest level since January.
 

 Today and tomorrow are looking to be similarly pleasant.

 

Edit: The forecasted MJO phase 1 (and possibly 2 soon after) favors BN in the SE in April.

[GaWx]

 Details mainly for entertainment due to it being a cold outlier: The 12Z Euro is its coldest run yet in the SE for early next week and is significantly colder than the 12Z GFS (both meaning it is likely too cold) with 0C 850s getting just about down to here and a low of 39 at ATL on 4/24 along with several inches of upslope snow in the mountains along the TN/NC border this weekend into early next week.

 Despite it likely being too cold, a BN pattern would be supported for then especially by a preceding sub -3 AO (lowest since December) and MJO phase 1. A dropping NAO probably helps, too, although by April correlations of -NAO to cold in the deep SE on average drop significantly vs March per charts. Even after then, the GEFS has a pretty strong +PNA for at least a few days very late this month. That could allow for still another cool/mild (BN and low dewpoints) shot of Canadian air then.

[WinstonSalemArlington]

 

[franklin NCwx]

1 hour ago, GaWx said:

 Details mainly for entertainment due to it being a cold outlier: The 12Z Euro is its coldest run yet in the SE for early next week and is significantly colder than the 12Z GFS (both meaning it is likely too cold) with 0C 850s getting just about down to here and a low of 39 at ATL on 4/24 along with several inches of upslope snow in the mountains along the TN/NC border this weekend into early next week.

 Despite it likely being too cold, a BN pattern would be supported for then especially by a preceding sub -3 AO (lowest since December) and MJO phase 1. A dropping NAO probably helps, too, although by April correlations of -NAO to cold in the deep SE on average drop significantly vs March per charts. Even after then, the GEFS has a pretty strong +PNA for at least a few days very late this month. That could allow for still another cool/mild (BN and low dewpoints) shot of Canadian air then.

Called this over the winter

[eyewall]

Yep we always get the right setup when it is too late.

[GaWx]

 The Happy Hour Goofy is BN dominated in the SE throughout the run.

[wncsnow]

We may not see 80 again until mid May in WNC

[Daniel Boone]

On 4/18/2023 at 2:28 PM, eyewall said:

Yep we always get the right setup when it is too late.

Yep, never fails when the pattern is what we had during Winter. 

[WinstonSalemArlington]

 

[GaWx]

Does anyone here know what happened in Atlanta 113 years ago tomorrow (4/25)?

[Jmoon]

1 hour ago, GaWx said:

Does anyone here know what happened in Atlanta 113 years ago tomorrow (4/25)?

They got around 1.5 inches of snow and the temperature dropped down to 32 degrees 113 years ago tomorrow. I sure wish it was happening again tomorrow but pretty unbelievable it happened in Atlanta at all so close to May. 

[GaWx]

13 hours ago, Jmoon said:

They got around 1.5 inches of snow and the temperature dropped down to 32 degrees 113 years ago tomorrow. I sure wish it was happening again tomorrow but pretty unbelievable it happened in Atlanta at all so close to May. 

 To add to what you said, Atlanta had a high on 4/25/1910 of only 39. After March 26th (going back to 1879), they have had highs below 40 only three times: 39 on 4/3/1987, 36 on 4/5/1891, and 39 on 4/25/1910. So, the 4/25/1910 very cold high really stands out in the record books for how late it is.

  This accumulating snow so late in April could easily be a once in several hundred year event and could even be a once in a thousand year event.

Edit: The old Atlanta newspapers that I read (on microfiche at the public library) and copied forecasted rain and warmer temperatures on April 25th, not snow and colder. April 24th was 18 BN (high of 56 and low of 38) and they thought that that was to be the coldest day of the cold snap. So, this was a big surprise even to the meteorologists!