1/28 - 1/30 Storm Thread II

[Shawn]

Euro holds with around 5 inches for KCAE.  Night.

[ILMRoss]

Virga storm already forming overhead and back through north Alabama. Radar is  starting to light up. Check this link from HSV............

 

 

http://radar.weather.gov/radar.php?rid=HTX&product=NCR&overlay=11101111&loop=yes

The virga storm is even starting to nudge into northern Georgia. Game on!

[GaWx]

 Interesting development on the 0Z Euro: it has that 2nd wave's precip., similar to the NAM. precariously close to the SE and much closer than the 12Z Euro. I suppose this is something to watch for a coastal surprise on Thu morning as temp.'s are still plenty cold enough for wintry then, especially considering possible model biases with precip. Actually, the NAM at 36-54 has JAX getting ZR.

 Also, the precip. is much slower to depart. Whereas the first wave left GA by ~5 AM on Wed. on the 12Z Euro, here the 2nd wave grazes the GA coast and doesn't leave til ~1 AM on Thursday.

[SnowGoose69]

00Z SPC WRF valid at 18Z

 

[Lookout]

The virga storm is even starting to nudge into northern Georgia. Game on!

Folks, don't make me be the bad guy.  Enough with these weenie posts. If you want to hoot, holler, see things in satellite imagery that isn't happening, have radar hallucinations,  or jump up and down go do it in the banter thread..or your living room. Just not in this thread.

[Stormsfury]

 The 0Z GFS, taken literally would give SAV hardly any ZR! It would be mostly a cold rain with a little IP/S toward the end. The only problem is that it had CHS getting down to 32 15 hours earlier and it at 4-5 degrees colder for much of the storm. Based on old wx maps, that is too much of a differential to persist for many hourswhen there's a setup like this. History tells me that once the Arctic air settles all the way to Savannah and things stabilize with a NNE to N flow bringing the CHS cold air all of the way down to SAV with no real ocean related modification, it almost never has remained 4-5 degrees warmer than CHS for hours on end. It is usually more like 1-2 degrees once things stabilize. So, I am educatedly guessing that they either have CHS too cold by ~2-4 degrees or SAV too warm by 2-4 degrees. I'm thinking the first is most likely but we'll see.

 

 SF, your thoughts about all of this?

Seriously don't think SAV stays ABV FRZ for long once CAA has blown thru there also.  Usually there's not much differential in temperatures usually about 2 degrees at most in this kind of environment with no oceanic effects.

[chapelhillwx]

DT's latest call map. Bullish on a NW trend, it seems. Of course, anyone in SC/GA probably shouldn't pay attention to him anyway; he just draws the lines once it gets outside of VA lol.

 

[Reb]

Folks, don't make me be the bad guy.  Enough with these weenie posts. If you want to hoot, holler, see things in satellite imagery that isn't happening, have radar hallucinations,  or jump up and down go do it in the banter thread..or your living room. Just not in this thread.

Not trying to dispute you or anything but virga is an important factor in moistening the atmosphere to allow it to snow. Virga this early could be key in certain locations, including N GA

[Lookout]

Not trying to dispute you or anything but virga is an important factor in moistening the atmosphere to allow it to snow. Virga this early could be key in certain locations, including N GA

I'm talking about the inevitable time period where people always see things in radar that aren't really happening. .like "it's exploding!". Just like above where you had people wrongly thinking there is some magical phase happening that no computer model or person saw coming.  It happens every time

 

And no, fwiw, virga right now doesn't mean much. It's been projected by the nam and rap for a long time and it's all very high up. In fact, I'd say it's actually a little behind right now vs what was being progged on earlier runs. Regardless, silliness like "game on!" for virga is a bit too much.

[SN_Lover]

SREF is a disaster....slashes accumulations across the board. 

 

RAP is a disaster for 1-85 W in NC. Completely extinguishes precip.  

[jacobr57]

SREF is a disaster....slashes accumulations across the board. 

Not necessarily. The western end of NC fairs pretty well, all things considered. It doesn't look quite as promising for the piedmont, however.

[GaWx]

 Interesting development on the 0Z Euro: it has that 2nd wave's precip., similar to the NAM. precariously close to the SE and much closer than the 12Z Euro. I suppose this is something to watch for a coastal surprise on Thu morning as temp.'s are still plenty cold enough for wintry then, especially considering possible model biases with precip. Actually, the NAM at 36-54 has JAX getting ZR.

 Also, the precip. is much slower to depart. Whereas the first wave left GA by ~5 AM on Wed. on the 12Z Euro, here the 2nd wave grazes the GA coast and doesn't leave til ~1 AM on Thursday.

 

 Further to my comments about the 2nd Gulf wave showing more of a threat to the coast for late Wed/early Thu on the 0Z NAM/Euro, you can add the 0Z UKMET to that list. It actually is causing a lengthening of the precip. through much of Wed. night. for the SAV-CHS corridor. The bulk of the precip. falling after 7 AM on Wed. is snow with probably a good 1-2" being shown on this run for much of this region. So, this could really get interesting, especially if it pulls even more moisture than it now being indicated. The trends have been going that way. We'll see.

[crossthread]

ILM mentioned the warm nose earlier this evening, saying it was a bigger threat east of I-95. They noted it was the factor threatening a major ZR event down along the beach. It could be extrapolated to cause early sleet in FAY, given the afternoon start of things. 

Forecasting up to 1/2 inch of ICE/ZR before changing ALL snow, 2-5 inches..

[crossthread]

Here is a picture/still of that water vapor Loop, **Panel 24**, T My un-trained eyes, It appears to Me that "Baha"? Low makes a "jump" across Mexico practically being SUCKED IN with the northern SW; Piece of energy diving into north Texas, consolidating at the last panel, pictured here... This would be a PHASE, correct? Thoughts on this, development? good/bad?

LOOP_> http://www.meteo.psu.edu/ewall/SAT_US/animwv.html

[ncskywarn]

Morning AFD

from Raleigh NWS

 

 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
315 AM EST TUE JAN 28 2014

.SYNOPSIS... A LOW PRESSURE SYSTEM WILL DEVELOP OFFSHORE THE
SOUTHEAST COAST TODAY...THEN TRACK NORTHEAST OFFSHORE THE CAROLINA
COAST TONIGHT. ARCTIC HIGH PRESSURE WILL REMAIN IN PLACE WEDNESDAY
AND THURSDAY.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
AS OF 315 AM TUESDAY...

LATEST MODEL GUIDANCE AND CURRENT ANTECEDENT CONDITIONS STILL POINT
TO A MAJOR WINTER WEATHER EVENT FOR MUCH OF CENTRAL NC LATER TODAY
THROUGH TONIGHT. ADJUSTED ADVISORY TO INCLUDE ALL OF THE TRIAD AND
HAVE ENDED THE ADVISORY/WARNING A FEW HOURS EARLIER.

NLY WINDS BEHIND THE ARCTIC BOUNDARY WHICH CROSSED OUR REGION LATE
MONDAY AND MONDAY EVENING HAS FUNNELED MUCH COLDER AND DRIER AIR
INTO THE REGION. DEWPOINTS BELOW ZERO BEING OBSERVED FROM A NUMBER
OF SITES ACROSS THE NORTHERN PIEDMONT. THIS AIR MASS WILL CONTINUE
TO SURGE SOUTH INTO THE SANDHILLS AND SOUTHERN COASTAL PLAIN.

WATER VAPOR IMAGERY DEPICTS A DEFINITE JET STREAK LIFTING NEWD
ACROSS THE TN VALLEY INTO THE CENTRAL APPALACHIANS. THIS FEATURE
WILL CONTINUE TO LIFT NE...PLACING CENTRAL NC IN THE FAVORABLE RIGHT
ENTRANCE REGION THIS AFTERNOON-EARLY EVENING. THIS FEATURE WILL AID
TO CAUSE PATCHES OF LIGHT SNOW TO DEVELOP IN VICINITY OF TEH NW
PIEDMONT THIS AFTERNOON.

A SERIES OF VORTICITY MAXIMA WILL ADVANCE EWD ACROSS THE GULF COAST
STATES AND THE SE U.S. LATER TODAY AND TONIGHT. ALREADY SEEING
PRECIP INCREASE IN COVERAGE AND INTENSITY ACROSS COASTAL SC IN
VICINITY OF HILTON HEAD AND CHS. THE INITIAL VORT MAX WILL INDUCE
MODEST ISENTROPIC LIFT OVER THE SANDHILLS AND SOUTHERN COASTAL PLAIN
BY LATE MORNING OR EARLY AFTERNOON. THIS INITIAL ONSET OF PRECIP
WILL AID TO MOISTEN A VERY DRY SUB CLOUD LAYER. ONCE THIS IS
ACHIEVED...EXPECT PRECIP TO BECOME MORE WIDESPREAD LATE THIS
AFTERNOON INTO THE EVENING HOURS AS A STRONGER VORT MAX APPROACHES
FROM THE WEST. DECENT FRONTOGENESIS IN THE 700MB-300MB LAYER (WELL
WITHIN THE FAVORED ICE NUCLEATION REGION) WILL GENERATE SNOW ACROSS
MOST OF THE REGION.

TIMING WISE...WHILE A FEW PATCHES OF WINTRY PRECIP CANNOT BE RULED
OUT THIS MORNING ACROSS THE FAR SOUTHERN COUNTIES...BULK OF
PRECIPITATION WILL OCCUR FROM MID-LATE AFTERNOON THROUGH THE EVENING
HOURS THEN TAPER OFF/END WEST-TO-EAST OVERNIGHT. INTERESTING TO NOTE
THAT SOME OF THE NEAR TERM GUIDANCE SUGGEST THAT MOST OF THE
TRIANGLE AREA IS IN A PRECIP FREE REGION FOR MOST OF THE DAY. SOME
MODEL GUIDANCE DOES NOT DEPICT MEASURABLE PRECIP IN THE RDU VICINITY
UNTIL 21Z-00Z.

AS IS THE CASE MOST TIMES...PRECIP AMOUNTS STILL QUESTIONABLE AND
VARIABLE AMONG THE MODEL GUIDANCE. FAVORED THE MORE CONSERVATIVE AND
CONSISTENT ECMWF THIS MODEL RUN. IF GFS AMOUNTS VERIFY...COULD SEE
AN ADDITIONAL SNOW AMOUNTS OF 1-2 INCHES EAST OF HIGHWAY 1.

WHILE SNOW WILL BE THE PREDOMINATE PRECIP TYPE...GFS BUKFIT SOUNDING
DATA DOPES DEPICT A MODEST WARM NOSE (1-1.5 DEG C) OVER THE
SANDHILLS AND SOUTHERN COASTAL PLAIN DURING THE DAYLIGHT HOURS
TODAY. DURING TIMES OF RELATIVELY LIGHT PRECIP INTENSITY...EXPECT A
MIXTURE OF SNOW AND SLEET. WHEN PRECIP INTENSITY INCREASES...EXPECT
BULK OF PRECIP TO BE SNOW. AS COLUMN COOLS LATE TODAY INTO THIS
EVENING...DOMINATE PRECIP TYPE WILL BE ALL SNOW. IF MIXTURE OF
SNOW/SLEET PERSIST LONGER THAN EXPECTED...THIS WILL CUT INTO
EXPECTED SNOW AMOUNTS.

AS FAR AS SNOW-TO-LIQUID RATIO...STARTED OUT 10:1-12:1 INT EH NW
PIEDMONT...TRENDING TO 15:1 LATE THIS AFTERNOON-EVENING. ACROSS THE
NE PIEDMONT INTO THE NORTHERN COASTAL PLAIN...FAVORED 12:1 FOR THE
BULK OF THE EVENT. IN TEH SANDHILLS/SOUTHERN COASTAL PLAIN...IN
ANTICIPATION OF A SLEET MIXTURE...USED 7:1 THROUGH MID AFTERNOON
THEN TRENDED TO 10:1 BY THIS EVENING WITH 12:1 AT THE END OF THE
EVENT. CAME UP WITH SNOW TOTALS OF 1-2 INCHES IN THE NW PIEDMONT...2-
4 ALONG THE HIGHWAY 1 CORRIDOR (20 MILES EITHER SIDE)...AND 5-7
INCHES OVER THE EASTERN SANDHILLS AND CENTRAL/SOUTHERN COASTAL
PLAIN. POTENTIAL EXISTS FOR LOCALLY HIGHER AMOUNTS (8+ INCHES) OVER
PARTS OF THE COASTAL PLAIN.

MODEL GUIDANCE HAS COME INTO CONSENSUS ENDING THE EVENT PRIOR TO
DAYBREAK. BASED ON THIS...HAVE TWEAKED THE ENDING TIME OF THE
ADVISORY/WARNING TO 9 AM...AND THIS STILL MAY BE TOO TARDY.

[Cyric297]

Here is a picture/still of that water vapor Loop, **Panel 24**, T My un-trained eyes, It appears to Me that "Baha"? Low makes a "jump" across Mexico practically being SUCKED IN with the northern SW; Piece of energy diving into north Texas, consolidating at the last panel, pictured here... This would be a PHASE, correct? Thoughts on this, development? good/bad?

LOOP_> http://www.meteo.psu.edu/ewall/SAT_US/animwv.html

 

I could be wrong, but no, I do not believe this is what you are seeing.  The actual vorticity of the baja low is much further south and west than the area you are depicting.  However, I do believe this is the weak vorticity that the N/S energy is absorbing that has caused it to move further west and south as was depicted in the model runs earlier in the day, thus leading to higher QPF estimates to the north and west of the original precipitation shield in the models a day ago.  

 

Phil882 had a great post earlier about how these vorticity steamfunction winds worked here http://www.americanwx.com/bb/index.php/topic/42584-128-130-storm-thread-ii/page-44#entry2690224

 

So looking at this map:

 

 

 

You can see the vort max over baja and another, I believe, over Colorado.  

 

Now I'm not saying it will or won't happen, but I don't believe that's what is happening currently on the WV.  

[mikepie]

FFC has expanded WSW to include all of metro Atlanta.

[crossthread]

Short term /6 am this morning through Wednesday night/...
as of 300 PM Monday...a major winter weather event is still
expected. The main difference between the model runs on sun and
those of today is that the deep and pronounced warm nose that was
very evident earlier is now that much more exaggerated...

 

Which Model(s) a few people chimed in that had a WARM BIAS to them???

 

up to 5 to
7 degree c along the coast. Inland...across the Interstate 95
corridor...the warm nose is not quite as significant...but still up
to 1 to 3 degree c around 5 kft. Thus the model soundings are above
freezing in a 2 to 4 kft layer and the above freezing layer has
lowered closer to the ground. While it is true that dynamic cooling
could cool the column...it is unlikely it will be able to bring the
column below freezing throughout and this is especially true at and
nearer to the coast. The consequences of this is that we are now
expecting more freezing rain. Along and east of a flow to CPC to
Burgaw line...ice accumulations of a tenth to a quarter of an inch
are expected with up to a half inch or more along the coast.

 

The worst of the ice is expected in a corridor from Surf City and ilm to
the grand strand and down through Georgetown and back across Andrews
and Conway and most of Brunswick County. Where the precipitation
remains mainly snow...snow amounts may reach 4 to 6 inches and
higher amounts are possible. The heaviest snow at this time is
expected from Watha and eyf to Dillon and Darlington and points northwest.
Even where mainly snow is expected...there will likely be some
period of time where sleet is able to mix in...especially during the
day Tuesday. Also...even where freezing rain dominates early in the
event...there will be a changeover to all snow and so coastal areas
should see at least a couple inches of snow before the event
ends...with possibly as much as 4 inches for some coastal locations.

The heaviest accumulations of snow and ice are expected later Tuesday
afternoon and at night. The precipitation is expected to begin as
early as early Tuesday morning along portions of the coast and
southernmost areas...expanding north and west to include more inland areas
through midday. The precipitation will be heaviest later Tuesday
afternoon and night with the precipitation winding down from inland
to the coast Wednesday morning. As the cold air deepens Tuesday evening...the
mixed precipitation will change to all snow...lastly at the coast
late in the evening. All snow is expected overnight.

The Arctic front will be offshore by Tuesday morning with waves of low
pressure developing and moving up along the boundary. As the Arctic
air moves out across the waters...it will help to increase the
baroclinicity of the environment...helping to fuel developing low
pressure. However...at this time there does not appear to be
sufficient time for adequate pre-conditioning of the environment and
so the waves of low pressure are not expected to deepen
significantly while they are down around our latitude. The Arctic
air will be shallow and slow to deepen...with winds from the
north from the surface to about 3 kft.

 

Above that level...strong
winds will remain from the west-southwest or SW. This will create a strong
overrunning situation. Isentropic lift is expected to increase
sharply Tuesday afternoon and to maximize Tuesday evening and night.

As the pressure gradient tightens late tonight and Tuesday morning...
north winds of 20 to 30 miles per hour are expected to develop and continue
through the height of the storm. Where snow remains the dominant
precipitation type...these winds will serve to blow and drift the
snow while bringing wind chills down to around 10 degrees. Temperatures Tuesday
are not expected to get above the freezing mark...and will actually
have a tendency to drop slowly through the 20s as the precipitation
becomes heavier as low wet bulb temperatures attempt to recover. Temperatures will
be well down in the 20s Tuesday night and given the snow and ice on the
ground on Wednesday...we are forecasting highs to remain below freezing on
Wednesday as well. Temperatures may not actually get above freezing until Thursday
afternoon...so significant snow and ice accumulations will remain in
place for perhaps several days.
 

[GaWx]

 Further to my comments about the 2nd Gulf wave showing more of a threat to the coast for late Wed/early Thu on the 0Z NAM/Euro, you can add the 0Z UKMET to that list. It actually is causing a lengthening of the precip. through much of Wed. night. for the SAV-CHS corridor. The bulk of the precip. falling after 7 AM on Wed. is snow with probably a good 1-2" being shown on this run for much of this region. So, this could really get interesting, especially if it pulls even more moisture than it now being indicated. The trends have been going that way. We'll see.

 

 And now I'll add the 0Z CMC and the 6Z NAM to the 0Z NAM/EURO/UKMET that have that second Gulf wave either precariously close to or actually grazing the SE coast for late Wed/early Thu while the atmosphere is still cold enough for wintry precip. Actually, the 12Z CMC also had it. The 6Z NAM actually has snow falling from it near the coast wed night/Thu morning. It has the GOM weak low move across south FL but a little NW of the 0Z NAM, thus allowing the precip. to actually graze the coast. If this were to have its track come in only about 100-150 miles further NW, we'd probably be then looking at a 2nd wave of wintry event on/near the coast Wed. night /Thu morning, which could easily include a lot more snow than the first wave ends up producing since 850's ae already below 0C.

 

 Based on latest model trends as well as current trends vs. the 1st wave progs, I think that more and more attention will start getting paid toward wave #2, especially starting late tomorrow. I think it is a sleeper. We'll see.

 

2) The E SC temp.'s continue the trend of being warmer than the GFS due I assume to a lag in the airmass finally getting there. Just something to follow. At the least this should delay SAV/CHs getting down to 32 vs. the 0Z GFS' timing.

[FLweather]

Latest Rap and NAM trends continue to build the western snowband from ATL to W NC.

 

Of Course heavier moisture axis is back further west compare to the 0Z runs.

[jacobr57]

Latest Rap and NAM trends continue to build the western snowband from ATL to W NC.

Of Course heavier moisture axis is back further west compare to the 0Z runs.

I saw that. The RAP in particular has some incredible returns for northern georgia. Its really the best case scenario for those at the western end. Based on the other models it looks like its quite a bit overdone though.

[FLweather]

I saw that. The RAP in particular has some incredible returns for northern georgia. Its really the best case scenario for those at the western end. Based on the other models it looks like its quite a bit overdone though.

 

Yeah it does look wetter but not by much from Nam.

 

Interesting to see how that  band develops bc if the rap is right then there will pockets of .3-.5" in the western band. Even with higher ratios several inches could be possible.

 

Radar really is expanding atm sure it will get better over the next few hours.

[DaculaWeather]

[Tyler Penland]

I saw that. The RAP in particular has some incredible returns for northern georgia. Its really the best case scenario for those at the western end. Based on the other models it looks like its quite a bit overdone though.

 

I would take the RAP in a heartbeat. It "looks" overdone but it hasn't backed down since it started showing that band when it first came in range. It's waffled a tad on location since and precise amounts, bu tit has had a band into north GA for a while now.  

[Vorticity]

09 Rap shows a max temp (2m) in ATL of 44 wtf? with snow?

[John1122]

Is it me or is the radar blooming much more than had been modeled? This is playing out very much like Robert has predicted so far.

[FallsLake]

Looking at the high resolution NAM simulated radar it looks like there is going to be a 21 hour period where snow will be falling at RDU. 15 of the hours look to have at least moderate returns. Here's one image at hour 18; but there are 5 others(3 hr increments) that look similar (for RDU). **that would be impressive for many on this board.

 

  

[RaleighWx]

Looking at the high resolution NAM simulated radar it looks like there is going to be a 21 hour period where snow will be falling at RDU. 15 of the hours look to have at least moderate returns. Here's one image at hour 18; but there are 5 others(3 hr increments) that look similar (for RDU). **that would be impressive for many on this board.

 

  

 

 

 

Looking at the high resolution NAM simulated radar it looks like there is going to be a 21 hour period where snow will be falling at RDU. 15 of the hours look to have at least moderate returns. Here's one image at hour 18; but there are 5 others(3 hr increments) that look similar (for RDU). **that would be impressive for many on this board.

 

  

 

4km NAM also has a bit more precip than the 40km nam over Triangle.

[FLweather]

09 Rap shows a max temp (2m) in ATL of 44 wtf? with snow?

 

Yeah I noticed that warm bubble on that run. Its probably wrong in regards to surface temps with the amount of moisture streaming over head. No way ATL makes into the 40s.

 

But boy does it get wild with the simulated radar. Thats probably the best run yet for ATL and the Western Carolinas.

 

http://www.twisterdata.com/index.php?prog=forecast&model=RAP&grid=255&model_yyyy=2014&model_mm=01&model_dd=28&model_init_hh=09&fhour=01&parameter=CREF&level=SURFACE&unit=none&maximize=n&mode=loopmaps&sounding=n&output=image&view=large&archive=false

[DaculaWeather]

Just looking at the radar, it appears to me the lighter precip is along the coast, and it's heavier inland. 

 

http://www.daculaweather.com/current/misc/google-maps-radar/4_google_radar.php