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Wintry Possible Snow & Ice Threat Nov 14-15

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Brick Tamland said:
So, what's keeping this from happening? Because it is crazy for a model to show that much and there not be any frozen precip here.
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There is a strong warm nose aloft that is keeping this from being snow across NC/SC. The Tidbits maps see surface temperatures near freezing and calculate ice and cold rain of 33-34 as "snow" when in reality the only frozen precip will be in the immediate mountains. See the strong warm nose here.
fv3p_T850_us_9.png


Even the coldest portions of NC where the 850s are at or below 0C have a pronounced warm nose.
upload_2018-11-13_12-4-0.png
 
snowlover91 said:
There is a strong warm nose aloft that is keeping this from being snow across NC/SC. The Tidbits maps see surface temperatures near freezing and calculate ice and cold rain of 33-34 as "snow" when in reality the only frozen precip will be in the immediate mountains. See the strong warm nose here.
fv3p_T850_us_9.png


Even the coldest portions of NC where the 850s are at or below 0C have a pronounced warm nose.
View attachment 7359
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So, why can't the model take the warm nose into account?
 
Also note the warm air advection at the 850 and 700 levels is particularly strong due to the SE wind since the ULL is to our west/north.
nam3km_temp_adv_fgen_850_seus_49.png


Here's the 700mb level showing the warming temps aloft.
nam3km_temp_adv_fgen_700_seus_41.png
 
Brick Tamland said:
Maybe it would be better to just not post maps from Tropical Tidbits if they are not reliable.
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I agree, the methods used on Pivotal Weather are generally a bit more accurate and represent the overall atmosphere and sounding plots better as well. They're not perfect but you can see the vast difference between the two when ice and marginal temps are involved.
gfs_asnow_us_11.png


Snow.JPG
 
SnowNiner said:
Was just thinking the same thing. Well, at least now we know. FV3 just showed its hand....
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The FV3 snow map looks fine. It's the Tidbits clown maps that are the issue, not the GFS or FV3. Here is the FV3 with a better snow flag algorithm applied.
FV3.JPG

Compare with the Tidbits map for the same period.
fv3p_asnow_us_11.png


Also notice the p-type map on the FV3 for Tidbits correctly shows rain and ice in areas the snow map drops a foot or more of snow. The issue, again, is not with the model as it is with the Tidbits maps calculating ice and marginal 33-34 cold rain as snow.
fv3p_mslp_pcpn_frzn_us_8.png
 
accu35 said:
I don't think TT has an ice map, so there could be ice on there if so
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TT map includes ice like zr and ip and also includes marginal 33-34F temps in the snow map. It's inherently flawed and should not be used in a setup like this IMO.
 
snowlover91 said:
TT map includes ice like zr and ip and also includes marginal 33-34F temps in the snow map. It's inherently flawed and should not be used in a setup like this IMO.
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Last year we had this discussion about the Nam being overdone and December 7/8th storm hit, it was pretty darn close to it's accumulation TT map. But I get what your saying.
 
accu35 said:
Last year we had this discussion about the Nam being overdone and December 7/8th storm hit, it was pretty darn close to it's accumulation TT map. But I get what your saying.
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The difference in that storm though was the pivotal maps for the NAM were similar to the TT maps. Soundings are ultimately the best way to tell what’s going on but not many use those anymore.
 
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snowlover91 said:
The difference in that storm though was the pivotal maps for the NAM were similar to the TT maps. Soundings are ultimately the best way to tell what’s going on but not many people don’t use those anymore.
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I mean you can scroll through hour by hour and tell what’s falling as green and what’s falling as pink. Those TT precip maps will sucker you in though If you aren’t careful. Coldest rain of the season incoming
 
snowlover91 said:
The difference in that storm though was the pivotal maps for the NAM were similar to the TT maps. Soundings are ultimately the best way to tell what’s going on but not many use those anymore.
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I like the text soundings. Those bent line ones give me a headache. But soundings are great. And if there is a warm nose, it will likely be warmer than modeled.
 
FFC for the mountains :
Extended period begins with the culprit upper low exiting through
KY and Eastern TN and much of the moisture exiting to the east
with it. Mid level dry slot looks to work into the region during
the day Thursday from west to east so there should be a relatively
quick shut off to the rainfall. Late Thursday there appears to be
a window where there is enough wrap around moisture and cold air
across North GA that some snow showers could start mixing in.
Model soundings for that area suggest a shallow but saturated
subfreezing layer below about 850mb with drier air above it which
favors upslope snow showers. Have added snow showers which would
be more likely in the NW facing slopes during the evening hours on
Thursday into the first part of the overnight. Because the low is
rapidly exiting to the east...much of moisture evacuates quickly
with it so the window looks to be only about 6-9 hours or so. Have
not included any appreciable amounts but would not be surprised
to hear about a trace or dusting in some of the higher elevations.
Not anticipating any issues with the snow otherwise.
Click to expand...
I wonder if any will make it down here or not. I don't believe the NAM as I know better by now, but other models bring moisture in and are quite close to something.
 
I just hope here in Birmingham we squeeze out a few flurries. If Houston metro area does & we don't I might feel some type of way lmao
 
How about a mixed bag!!
..FLOOD WATCH IN EFFECT FROM WEDNESDAY EVENING THROUGH THURSDAY
EVENING...
...WINTER STORM WATCH IN EFFECT FROM WEDNESDAY EVENING THROUGH
THURSDAY AFTERNOON...

.TONIGHT...Cloudy. Lows in the upper 30s. North winds around
10 mph this evening, becoming light and variable.
.WEDNESDAY...Mostly cloudy. Highs in the upper 40s. Light and
variable winds, becoming northeast around 10 mph in the
afternoon.
.WEDNESDAY NIGHT...Rain or freezing rain. Ice accumulation of up
to one quarter of an inch. Lows in the lower 30s. Northeast winds
around 10 mph. Chance of precipitation near 100 percent.
.THURSDAY...Rain and freezing rain in the morning, then rain
likely in the afternoon. Highs in the upper 30s. Northeast winds
around 10 mph. Chance of precipitation near 100 percent.
.THURSDAY NIGHT...Mostly cloudy. A chance of rain or snow
showers, mainly in the evening. Little or no snow accumulation.
Near steady temperature in the mid 30s. Light and variable winds,
becoming northwest around 10 mph after midnight. Chance of
precipitation 50 percent.
 
Winter Storm Watches out for parts of Western NC.
325 PM EST Tue Nov 13 2018

...WINTER STORM WATCH IN EFFECT FROM WEDNESDAY EVENING THROUGH
THURSDAY AFTERNOON...

* WHAT...Heavy mixed precipitation possible. The precipitation
will be predominately freezing rain, but it may mix with rain
and sleet at times. Total ice accumulations from freezing rain
may reach one-quarter inch, with isolated pockets possibly
approaching one-half inch of ice along the immediate eastern
slopes of the Blue Ridge mountains. Total sleet accumulations
may range from one-tenth to one-half inch, especially just east
of the Blue Ridge.

* WHERE...Locations along the eastern slopes of the Blue Ridge
mountains and the immediately adjacent foothills of western
North Carolina.

* WHEN...From Wednesday evening through Thursday afternoon.

* ADDITIONAL DETAILS...Power outages and tree damage are likely
due to the ice. Sleet accumulations may make roads treacherous.
Travel may be quite hazardous in impacted areas. The hazardous
conditions could impact the morning commute on Thursday.


403 PM EST Tue Nov 13 2018

...WINTER STORM WATCH IN EFFECT FROM WEDNESDAY EVENING THROUGH
THURSDAY AFTERNOON...

* WHAT...Light to moderate icing possible. Total ice accumulations
of a quarter to six tenths of an inch possible.

* WHERE...Portions of southwest and west central Virginia, north
central and northwest North Carolina and southeast West
Virginia.

* WHEN...From Wednesday evening through Thursday afternoon.

* ADDITIONAL DETAILS...Power outages and tree damage are likely
due to the ice. Although road surfaces will be warm, some slick
spots could occur.
 
Well they are calling for ice on Thursday then changing to rain then changing to snow on Thurs night. Gonna be messy.
 
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