BTW, do ya have the Korean?
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Wintry Jan 15-16 Winter Storm Discussion & Obs
- Thread starter SD
- Start date
It would help, although a classic storm for a boardwide storm really involves the surface low staying just offshore in the Gulf and crossing over the FL panhandle (near JAX), then swinging up NE in the Gulf Stream 100-200 miles off the Atlantic Coast. The JMA is a little north of that.
I saw someone post it in the Whamby thread earlier. I need to reup my model subscriptions so I can look at it myself.BTW, do ya have the Korean?
Probably seeing more of that front end thump than other models before the ice storm. Assuming the NAMS will be able to hone in on this stuff soonSlight as it may be I'll take any improvement where I can get it lol
tennessee storm
Member
What’s that off of accu? Twc curious
I’m willing to bet the NAM isn’t gonna show much FGEN snow, but the hrrr will sniff it out
Transfer will occur along the mid level thermal gradient, right now that looks through the Carolinas with primary surface starting to crank near Florence and then up the coastal plain into the Mid Atlantic.
iGRXY
Member
Updated my thinking for the system so far. Nothing really different from what we've seen on the modeling so far. Probably will update this tomorrow after 12z if anything has trended better or worse and put out a first call map on Friday after 12z.
iGRXY
Member
Was reading the GSP discussion from 12:45 and they are pushing for the idea of more snow especially along 85. Thinking is it will be a bit colder than models are hinting at.
As of 320 am EST Wednesday: The latest guidance suite is starting to
feature a bit better agreement on the overall aspects of the winter
storm likely to impact the area over the weekend. However, there
remains some variation regarding low tracks, thermal profiles, and
QPF for various periods, and these details continue to make
precipitation types and amounts highly uncertain.
Nearly all solutions have trended toward cutting off the southern
portion of the split upper flow near the lower Mississippi River
Valley by late Saturday. In a slight role reversal over the past 24
hours, the ECMWF 500 mb prognostic now features a cutoff low with a
farther south low center position than the operational GFS. However,
both models agree fairly well on the general timing, migrating the
system over the Deep/Mid South Sunday and then over the Carolinas
Sunday night as the system phases back into the northern stream.
Meanwhile, sprawling surface high pressure from southern Ontario to
New England will establish a strong cold air damming configuration
east of the Appalachians ahead of the storm on Saturday. The
resulting surface-based cold layer is becoming one of the more
confident aspects of the upcoming weekend storm. The onset timing of
wintry precipitation, however, remains uncertain. There are hints of
weak and shallow upglide developing over the preexisting baroclinic
zone as early as late Friday night or Saturday morning, with the
isentropic lift slowly improving the day on Saturday well east of
the approaching system. The forecast features below guidance
temperatures and wintry ptypes at onset across the northern half.
The period of deepest moisture and best forcing now looks slated for
Saturday night through Sunday as a Deep South surface wave
transitions to the Carolina coast. Strong jet-level divergence is
indicated during this period and deformation zone forcing will
likely impact our area by Sunday, especially over western NC given
the current low track forecast. Precipitation types remain
challenging. Profiles have trended to stronger warm nosing across
the southern half of the area, with prolonged sleet and southern
tier freezing rain now quite possible. However, the operational
model runs appear warmer than most of the ensemble members, so much
of the QPF could still fall as snow. An ensemble approach has been
adopted for weekend profiles, which leads to more snow in the
forecast than might be indicated on operational model profiles. The
mixed ptype belt should especially impact locations southeast of I-
85, but with a changeover back to snow likely occurring from the
west throughout on Sunday night as the system pulls away to the
northeast. Scattered upslope snow showers should persist along the
TN border counties through Sunday night, and possibly well into
Monday, further enhanching snow amounts there. We are still a bit
out of the Winter Storm Watch timeframe, so this will remain
highlighted in the HWO. The main change will be the addition of
sleet and freezing rain to the forecast, especially across the
southeast part of the area.
As of 320 am EST Wednesday: The latest guidance suite is starting to
feature a bit better agreement on the overall aspects of the winter
storm likely to impact the area over the weekend. However, there
remains some variation regarding low tracks, thermal profiles, and
QPF for various periods, and these details continue to make
precipitation types and amounts highly uncertain.
Nearly all solutions have trended toward cutting off the southern
portion of the split upper flow near the lower Mississippi River
Valley by late Saturday. In a slight role reversal over the past 24
hours, the ECMWF 500 mb prognostic now features a cutoff low with a
farther south low center position than the operational GFS. However,
both models agree fairly well on the general timing, migrating the
system over the Deep/Mid South Sunday and then over the Carolinas
Sunday night as the system phases back into the northern stream.
Meanwhile, sprawling surface high pressure from southern Ontario to
New England will establish a strong cold air damming configuration
east of the Appalachians ahead of the storm on Saturday. The
resulting surface-based cold layer is becoming one of the more
confident aspects of the upcoming weekend storm. The onset timing of
wintry precipitation, however, remains uncertain. There are hints of
weak and shallow upglide developing over the preexisting baroclinic
zone as early as late Friday night or Saturday morning, with the
isentropic lift slowly improving the day on Saturday well east of
the approaching system. The forecast features below guidance
temperatures and wintry ptypes at onset across the northern half.
The period of deepest moisture and best forcing now looks slated for
Saturday night through Sunday as a Deep South surface wave
transitions to the Carolina coast. Strong jet-level divergence is
indicated during this period and deformation zone forcing will
likely impact our area by Sunday, especially over western NC given
the current low track forecast. Precipitation types remain
challenging. Profiles have trended to stronger warm nosing across
the southern half of the area, with prolonged sleet and southern
tier freezing rain now quite possible. However, the operational
model runs appear warmer than most of the ensemble members, so much
of the QPF could still fall as snow. An ensemble approach has been
adopted for weekend profiles, which leads to more snow in the
forecast than might be indicated on operational model profiles. The
mixed ptype belt should especially impact locations southeast of I-
85, but with a changeover back to snow likely occurring from the
west throughout on Sunday night as the system pulls away to the
northeast. Scattered upslope snow showers should persist along the
TN border counties through Sunday night, and possibly well into
Monday, further enhanching snow amounts there. We are still a bit
out of the Winter Storm Watch timeframe, so this will remain
highlighted in the HWO. The main change will be the addition of
sleet and freezing rain to the forecast, especially across the
southeast part of the area.
One thing I noticed was the 12 NAM had a much stronger CAD taking hold than the 12 GFS at hour 84. The NAM had dew points 10 degrees colder in spots and the pressure push down the east coast was more pronounced.
The NAM should be heeded strongly with this storm. It does a great job with CAD, IMO, and also does a great job at sniffing out snow-melting mid level warm tongues. Good observations. Obviously a bit far out in the LR for the NAM, but I think this can still be useful!! Almost time for the 18z run, too, haha.
Models usually underdo CAD, though I sometimes wonder if this is somewhat a relic of the past as resolution has greatly improved since even I started watching models 13 (!!!) years ago. Curious if it’s as true as it once was? Might be a discussion in and of itself, though.
iGRXY
Member
NAM is similar. Still with a more sheared look.
fwiw:
WPC says:
The blend for the updated WPC medium range forecast used a general
model consensus (leaning more towards the ECMWF) for days 3-4.
After that, began incorporating some modest amounts of the
ensemble means to help temper the late period uncertainties.
Overall, this led to a fairly consistent forecast with the
overnight WPC package.
WPC says:
The blend for the updated WPC medium range forecast used a general
model consensus (leaning more towards the ECMWF) for days 3-4.
After that, began incorporating some modest amounts of the
ensemble means to help temper the late period uncertainties.
Overall, this led to a fairly consistent forecast with the
overnight WPC package.
If you remember that early February system last year that gave the Upstate and southern mountains and foothills a decent FGEN snow was picked up first by the hrrr while the NAM was showing nothing, and only corrected in the last 8-10 hours
iGRXY
Member
One thing I am noticing is the NAM is slowing down our first wave that will move to be our 50/50 low. That is a good thing as it is moving more in conjunction with our storm and can keep HP building deep into the area. It also continuing to strengthen the 50/50 thru 42.
SnowNiner
Member
That was this morning I think. I'm sure there will a mixed bag forecasted this afternoon.
Here's the funny thing. This thing is still 4-5 days out (it's slowed). If I were a betting man, I'd say this storm will look significantly different come Saturday on modeling one way or another.
iGRXY
Member
Said the same thing about that being from this morning, but I looked at my forecast and they have all snow for it so the thinking is clearly remained so far.