Mid to Long Range Discussion ~ 2023

[eyewall]

48 minutes ago, wncsnow said:

Mid March could be a legit threat for wintry in NC. Especially I 40 north. 

Lock it in!

[GaWx]

 Looking at the monthly NAO table back to 1950, the above maps are actually for when the March NAO averages lower than -0.5. The NAO looks to start that way but it remains to be seen whether or not it will stay predominantly negative enough through the month for it to end up sub -0.5. However, with the strong start being helped by the very weak SPV, I think the odds are pretty high.

 NAO monthly table:

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table

[GaWx]

The correlation of a -NAO with BN SE temps is higher during March vs all other months:

https://psl.noaa.gov/cgi-bin/data/correlation/corr.test1.pl?iregr=1&var=Air+Temperature&level=Surface&mon1=3&mon2=3&iy[1]=&iy[2]=&ilead=0&ilag=0&type=3&timefile=&customtitle=&labelc=Color&labels=Shaded&cint=&lowr=&highr=&scale=&switch=0&proj=USA&xlat1=&xlat2=&xlon1=&xlon2=&custproj=Cylindrical+Equidistant&level1=1000mb&level2=10mb&Submit=Create+Plot

Edit: Also, the correlation to BN in the SE during March is higher for -AO and -NAO vs any other indices such as +PNA.

[GaWx]

The 12Z EPS is by a good margin the coldest run yet for much of the E US!

[Met1985]

14 minutes ago, GaWx said:

The 12Z EPS is by a good margin the coldest run yet for much of the E US!

Yeah was just going to post about another really cold run for the Midwest and the Eastern US. 

[StantonParkHoya]

Looks short lived thankfully. Terrible for agriculture.

[Met1985]

21 minutes ago, StantonParkHoya said:

Looks short lived thankfully. Terrible for agriculture.

Not really. We are currently in the midst of another major SSW that will impact a good portion of April in my opinion. Lots of variables and changes going on.

[StantonParkHoya]

37 minutes ago, Met1985 said:

Not really. We are currently in the midst of another major SSW that will impact a good portion of April in my opinion. Lots of variables and changes going on.

That’s good if you like cool rain. It’s not 1962. You’re not getting snow in April. I, like most sane people, prefer Spring and being outdoors.

[NorthHillsWx]

4 minutes ago, StantonParkHoya said:

That’s good if you like cool rain. It’s not 1962. You’re not getting snow in April. I, like most sane people, prefer Spring and being outdoors.

I mowed my yard for the second time this year today. Was quite nice out. Had to spray the plethora of weeds that have taken off. Without exaggeration, we are more than a month ahead of schedule for the growing season. 

[franklin NCwx]

17 minutes ago, StantonParkHoya said:

That’s good if you like cool rain. It’s not 1962. You’re not getting snow in April. I, like most sane people, prefer Spring and being outdoors.

Might want to check climo before making bad posts. Most of us (especially the mtns) average more snow in April than November 

[StantonParkHoya]

7 minutes ago, franklin NCwx said:

Might want to check climo before making bad posts. Most of us (especially the mtns) average more snow in April than November 

I checked my climo. In April, we average 73 degrees. It’s not snowing. No one lives in Franklin. 

[Buckethead]

I checked my climo. In April, we average 73 degrees. It’s not snowing. No one lives in Franklin. 

I had 9" of snow just before Good Friday last year.

And I don't live in Franklin.

Sent from my SM-S908U using Tapatalk

[Met1985]

26 minutes ago, StantonParkHoya said:

I checked my climo. In April, we average 73 degrees. It’s not snowing. No one lives in Franklin. 

I mean realistically people outside the mountains have a very low chance of see snow but yall aren't out of the woods for some cold temps for sure. 

[buckeyefan1]

GSP's take on Friday

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 130 PM EST Tuesday: A positively-tiled upper trough will
dig across the western CONUS during the beginning portions of the
forecast period, while an attendant frontal boundary stretches from
the Southern Plains, through the ArkLaTex region, and into the
OH Valley and northeastern CONUS. As the pattern evolves through
the period, expect the frontal boundary to sag into the Southeast
Wednesday night into Thursday as the parent low lifts into the
northeastern CONUS. With a surface high shifting offshore and
the flow aloft gaining a southwesterly component, deep moisture
advection and low-level convergence will lead to a swath of precip
to push into the CFWA during the alluded timeframe. With a 40-50 kt
LLJ and scattered upper forcing to go along with high PWAT values
(1.00"-1.50+"), expect precip rates to be enhanced, which ultimately
may lead to a low-end hydro threat. Model guidance continue to
show the alluded frontal boundary stalling over the CFWA Thursday,
which may lead to an extended period of precip. As a result, likely
to categorical PoPs will remain in the forecast on Thursday. While
the frontal boundary remains stalled over the region, the positively
tilted trough will strengthen into a vertically stacked low over
the Four Corners region and shift to the Southern Plains Thursday
night. The surface low riding underneath will undergo cyclogenesis
and rapidly strengthen as it rides along the stalled boundary and
lifts in the mid-MS Valley. The stalled boundary over our CFWA will
activate into a warm front in response and lift well north of the
CFWA by Friday morning. This will set the area under a stout warm
sector regime, ahead the approaching frontal system.

Underneath the aforementioned warm sector, an environment favorable
for severe weather will be in store. The cold front attached
to the surface cyclone will be strongly forced as it encroaches
the CFWA by Friday afternoon. Model guidance continue to support
500-1000 J/kg of SBCAPE across the area as the front enters the
CFWA. Great deep layer shear and unidirectional hodographs support
the development of a squall line as the main frontal zone swings
through the CFWA. Mini-supercells could form out ahead of the
front as well. In this case, all three severe hazards will be
possible with damaging straight-line winds and a few embedded
tornadoes being the main focus. With the forward progression of
this system being relatively quick, any hydro threat will be low
and localized. One caveat being thrown into this forecast is the
timing between global models and the pesky NAM. Global models
are still in great consensus and that the main frontal band will
push through the area during peak heating. On the other hand,
the NAM is slower in the front`s progression and appears to push
the front across the CFWA just after peak heating, which could
limit the overall severe threat as a result. This will be a trend
to watch out for, especially once the hi-res models start to get
a handle on this setup on Wednesday. We urge everyone to continue
monitoring the forecast leading up to Thursday and Friday as it will
change between now and then, but the run-to-run consensus between
all operational models and ensembles makes it hard to believe that
there won`t be at least a low-end severe threat across the western
Carolinas and northeast Georgia. Temperatures through the period
will be well-above normal.

[franklin NCwx]

56 minutes ago, StantonParkHoya said:

I checked my climo. In April, we average 73 degrees. It’s not snowing. No one lives in Franklin. 

Glad we don't live there! Apparently it doesn't snow in winter in Raleigh either. Unfortunately, too many people live in Franklin. 

[calm_days]

Some chilly periods in March and April would probably be preferable to actual heat from February through late autumn sometime!! 

(also i feel like if you put a vote up in Southeastern States if we were ready for a cooler than average summer, there would be lots of yes votes!!)

[GaWx]

 The chances of the upcoming March NAO ending up sub -0.5 is pretty good considering how displaced/weak is the strat and how negative it is progged to be for the first 10 days. Since 1950, there have been 20 of these out of 73 (just over 1 in 4 chance). I did some calculations based on these 20 for RDU:

1. Temperature:

7 MB, 5 B, 7 N, 1 A (60% MB to B, 35% N, 5% A)

AVG -2.8

 

2. Snow/IP (I didn't do ZR):

- Measurable in 8 of 20 (40% of these vs 33% of all)

- 4"+ in 3 of 20 (15% of these vs 10% of all)(all 3 cold)

- Max 9.3" (1969)

- Average: 1.2" vs longterm average for all of 1.1" (so not bad but not much difference from average considering the high percentage that were cold)

 

[KChuck]

5 hours ago, GaWx said:

 The chances of the upcoming March NAO ending up sub -0.5 is pretty good considering how displaced/weak is the strat and how negative it is progged to be for the first 10 days. Since 1950, there have been 20 of these out of 73 (just over 1 in 4 chance). I did some calculations based on these 20 for RDU:

1. Temperature:

7 MB, 5 B, 7 N, 1 A (60% MB to B, 35% N, 5% A)

AVG -2.8

 

2. Snow/IP (I didn't do ZR):

- Measurable in 8 of 20 (40% of these vs 33% of all)

- 4"+ in 3 of 20 (15% of these vs 10% of all)(all 3 cold)

- Max 9.3" (1969)

- Average: 1.2" vs longterm average for all of 1.1" (so not bad but not much difference from average considering the high percentage that were cold)

 

Appreciate all of your work!!! 

[olafminesaw]

The Triad gets a 3-5" snow after March 10th about every 15 years (2018, 1993, 1981, 1974, 1972, 1940). The latest 6" storm on record was March 9th 1960

[GaWx]

1. The 12Z EPS held consistent with the prior colder E US trend and has a stronger PNA trend in the 11-15 vs prior runs.

2. The -AO continues to trend in the stronger direction on the EPS and other models out near day 10. I wouldn't be surprised if this continues. I suspect this is because of the very weak SPV. The 10 mb winds at 60N dipped all of the down to -19 m/s yesterday, indicative of a very weak strat. A strong -AO is a primary effect of a successfully down-welled weak strat onto the troposphere.

[Upstate Tiger]

Severe threat still appears to be on schedule for Friday:

As of 225 PM EST Wednesday: A potent shortwave trough and closed
upper low will take on a negative tilt as it ejects out of the
Southern Plains Thursday night and lifts through the Tennessee
Valley and into Ohio on Friday. This will push a strong cold front
through the area that will bring a threat for severe thunderstorms.
A warm front will quickly lift north Thursday night into Friday
morning with the entire forecast area residing within an open warm
sector by the early afternoon hours. Upper 50s to low 60s dewpoints
will be common within the warm sector, which should be sufficient to
support 500-1500 J/kg of surface-based CAPE across the area with the
highest values across the Piedmont. This is concerning as shear
profiles will be quite impressive. A 50-60kt low-level jet
translating across Georgia and the Carolinas will help sweep out
large cyclonically curved hodographs with 400-500 m2/s2 of 0-1km SRH
and 40-45kts of 0-1km bulk shear. Deep-layer wind shear will also be
impressive on the order of 70-80kts. The resulting parameter space
will be more than supportive of all modes and hazards of severe
weather.

Details, however, will reside in the placement and magnitude of
forcing and where the best CAPE/shear balance sets up shop. A very
strong ~985mb surface low will lift into central Indiana with a pre-
frontal surface trough extending into northeast Georgia and the
Carolinas. While pressures will be low, the strongest surface
pressure falls and height falls aloft will be displaced just
northwest of the area. Early CAM/mesoscale guidance depicts a
scenario where forcing is just enough to instigate a cellular storm
mode while not being too strong for rapid upscale growth into a line
of convection. This solution would support a broken band of
supercells, which would yield a greater severe weather threat. The
other uncertainty is the CAPE/shear balance as warm mid-level
temperatures and poor lapse rates result in meager CAPE profiles.
Resulting updrafts could struggle with such a strong magnitude of
shear, but this could potentially be offset by stronger
forcing/kinematics. With that being said, the current slight risk
appears well placed across the area until details can get ironed
out. An upgrade to higher severe probabilities cannot be ruled out
either given the aforementioned parameter space. Winds will also be
gusty outside of the severe weather threat, especially during peak
heating/mixing within the warm sector. A high wind watch may
eventually be needed across the higher terrain in the mountains with
advisory level winds possible elsewhere.

[olafminesaw]

*Wedge Watch*

The GFS has the Triad in the low 70s Friday afternoon, while the hires NAM  keeps temps in the mid to upper 40s. 

I think I can count on a drizzly miserable Friday 

[GaWx]

 

 

Tropospheric NAM = AO

0Z GEFS based AO forecasts for March 6th: trend is downward:

2/26 run: -0.1

2/27 run: -0.5

2/28 run: -1.3

3/1 run: -1.5

 For March 10th, yesterday's 0Z GEFS had 0. Today's had -0.9.

 The 12Z EPS has a stronger -AO through most of its run through March 14th and that continues its trend since the 0Z 2/27 run.

[kayman]

1 hour ago, Upstate Tiger said:

Severe threat still appears to be on schedule for Friday:

As of 225 PM EST Wednesday: A potent shortwave trough and closed
upper low will take on a negative tilt as it ejects out of the
Southern Plains Thursday night and lifts through the Tennessee
Valley and into Ohio on Friday. This will push a strong cold front
through the area that will bring a threat for severe thunderstorms.
A warm front will quickly lift north Thursday night into Friday
morning with the entire forecast area residing within an open warm
sector by the early afternoon hours. Upper 50s to low 60s dewpoints
will be common within the warm sector, which should be sufficient to
support 500-1500 J/kg of surface-based CAPE across the area with the
highest values across the Piedmont. This is concerning as shear
profiles will be quite impressive. A 50-60kt low-level jet
translating across Georgia and the Carolinas will help sweep out
large cyclonically curved hodographs with 400-500 m2/s2 of 0-1km SRH
and 40-45kts of 0-1km bulk shear. Deep-layer wind shear will also be
impressive on the order of 70-80kts. The resulting parameter space
will be more than supportive of all modes and hazards of severe
weather.

Details, however, will reside in the placement and magnitude of
forcing and where the best CAPE/shear balance sets up shop. A very
strong ~985mb surface low will lift into central Indiana with a pre-
frontal surface trough extending into northeast Georgia and the
Carolinas. While pressures will be low, the strongest surface
pressure falls and height falls aloft will be displaced just
northwest of the area. Early CAM/mesoscale guidance depicts a
scenario where forcing is just enough to instigate a cellular storm
mode while not being too strong for rapid upscale growth into a line
of convection. This solution would support a broken band of
supercells, which would yield a greater severe weather threat. The
other uncertainty is the CAPE/shear balance as warm mid-level
temperatures and poor lapse rates result in meager CAPE profiles.
Resulting updrafts could struggle with such a strong magnitude of
shear, but this could potentially be offset by stronger
forcing/kinematics. With that being said, the current slight risk
appears well placed across the area until details can get ironed
out. An upgrade to higher severe probabilities cannot be ruled out
either given the aforementioned parameter space. Winds will also be
gusty outside of the severe weather threat, especially during peak
heating/mixing within the warm sector. A high wind watch may
eventually be needed across the higher terrain in the mountains with
advisory level winds possible elsewhere.

There's already a thread on it: 

https://www.americanwx.com/bb/topic/58949-march-3-severe-potential/

[LakeNormanStormin]

18Z GFS says no snow for you.

Winter is canceled for the Piedmont.

Time to chase twisters.

Or play twister.

[SnowDawg]

Anybody in here see the 12z Euro control? One of the best modeled fantasy storms I've seen in a while. An absolute legend that will never happen lol

[Coach McGuirk]

51 minutes ago, SnowDawg said:

Anybody in here see the 12z Euro control? One of the best modeled fantasy storms I've seen in a while. An absolute legend that will never happen lol

what does it show?

[buckeyefan1]

32 minutes ago, Coach McGuirk said:

what does it show?

[Coach McGuirk]

46 minutes ago, buckeyefan1 said:

1993 pt deux

[PackGrad05]

Classic Wake County gradient.  By the time it got here (if it even was still a storm by then), it would have moved 100 miles NW.