N'ward shift in models for SE coast wintry threat

[LarryWx]

I'm surprised that nobody has said much (if anything) about the distinct northward shift as of the 0Z 12/24 runs of the model consensus with regard to the GOM low and its attendant precip. threat for the SE coast. The ECMWF, CDN ensemble, ETA, and GFS have all shifted northward with their latest runs. Has anyone noticed that the NW'ern extent of the 90-100% 850 mb rel. humidity field on the 12Z ECMWF is now just about on the SE coast vs. well offshore on earlier runs? I don't yet know if it is going to be cold enough for wintry precip. of some variety. However, for those wanting to see some, this northward shift should make those people feel the chances have increased somewhat from very low earlier. Looking at 850's tells me that sleet and/or freezing rain MAY be a bit more prevalent than snow if there is any wintry precip. Regardless, the projected track of the surface low is now almost on the perfect track, based on history, to give the SE coast its very rare shot at significant wintry precip. assuming it is cold enough.

Also, satellite photos of the area around TX suggest to me that the moisture may indeed be taking aim further north than the earlier further south model runs would have suggested.

Has anyone else noticed this?

One thing working against this is climo: FEB has been the most favored month despite the big 12/1989 dump.

[vbhoutex]

I haven't looked at the models yet, but having just come in from outside I can tell our humidity level is way up from what it was earlier this evening. Cloud deck has thickend and lowered considerably too. Temp i snow sitting right at 32º so we will get into the "cold enough" range. Question still is whether even if it feels like is there enough moisture to overcome the dry air at the lower levels?

[AL Chili Pepper]

I was sitting around waiting for the 06Z runs before I went to get a few z's. I've been waiting on somebody to say that! The 06Z ETA is well north of the 12Z run yesterday. Yesterday, it had the system crossing FL near Tampa. The latest has it near the Big Bend. The ETA is now in better alignment with the GFS. Another jog or two to the north and I'll feel a lot better about getting a few flakes out of it anyway.

[LaBreeze]

Simply a gut feeling on this - the moisture will remain offshore for the most part. I'm not thinking that we'll see any "white stuff" at all. As I stated, this is just a gut feeling.

[Stormcenter]

Simply a gut feeling on this - the moisture will remain offshore for the most part. I'm not thinking that we'll see any "white stuff" at all. As I stated, this is just a gut feeling.

Maybe not where you're at but those folks east of you will see more than expected. IMO

[AL Chili Pepper]

BTW, Alice International Airport just west of Corpus Christi is reporting light snow.

[mobilebay]

BTW, Alice International Airport just west of Corpus Christi is reporting light snow.

Hey pepper, I sure hope we get a few flakes today. How did you make it through Ivan?

[AL Chili Pepper]

BTW, Alice International Airport just west of Corpus Christi is reporting light snow.

Hey pepper, I sure hope we get a few flakes today. How did you make it through Ivan?

Hey guy. I spent the night at work trying to keep up with the leak in our "new" building. I work downtown, and the thing I remember most was the sound of the wind blowing between our building and the one across the street. It sounded like a 747 taking off. Winds on the battleship were reported at 101 mph before the computer failed.

When I got home, there were a few shingles missing and the wind had blown my gate down. I feel lucky. The guy across the street lost all of his siding. Just peeled it right off.

[Three Blind Mice]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
330 AM EST FRI DEC 24 2004

.SHORT TERM (TODAY THROUGH SATURDAY)...
COLD FRONT NOW OVER THE WATERS AND CONTINUING TO MOVE EAST. WEAK
SURFACE LOW/WAVE DEVELOP OFF THE CAROLINA COAST THEN HEAD NORTH
ALONG THE FRONT. THINK FEATURE WILL BE FAR ENOUGH OFF THE COAST
TODAY THAT THE ONLY IMPACT ON THE REGION MAY BE SOME OVERRUNNING
CLOUD COVER. DECENT CAA BEHIND THE FRONT TODAY RESULTING IN SOME
GUSTY WINDS THIS MORNING BUT THEN INCREASING CLOUD COVER WILL
CURTAIL WINDS.

COLD FRONT OFFSHORE WILL BE CLOSE ENOUGH TO GENERATE CLOUD COVER
ALONG THE COAST TODAY AND TONIGHT. HOWEVER FRONT WILL LIKELY BE TOO
FAR OFF THE COAST FOR PRECIP TO FORM. DRIER AIR INLAND WILL RESULT
IN A VERY TIGHT CLOUD COVER GRADIENT.

SATURDAY STILL LOOKS LIKE A TRICKY TEMPERATURE FORECAST WITH NORTH
WINDS AND SOME CLOUD COVER LINGERING AROUND. ETA MAY BE TOO QUICK TO
CLEAR OUT CLOUD COVER SATURDAY...LEADING TO ETAMOS NUMBERS THAT ARE
ON THE WARM SIDE. FOR NOW STICKING WITH HIGHS IN THE MID 40S AS
OPPOSED TO UPPER 40S/NEAR 50. FRONT MOVES SOMEWHAT CLOSER SATURDAY
AFTERNOON BUT STILL THINKING IT WILL BE TOO FAR OFFSHORE TO CAUSE
ANYTHING SIGNIFICANT TO HAPPEN.

&&

.LONG TERM (SATURDAY NIGHT THROUGH THURSDAY)...
LATE SATURDAY NIGHT AND SUNDAY COULD POSE A FEW PROBLEMS...FOR NOW
KEEPING FORECAST OPTIMISTIC. GFS/ETA/ECMWF ALL DEPICT SOMETHING
CLOSE TO MILLER TYPE A STORM SUNDAY...BUT HIGH APPEARS TO BE OUT OF
POSITION...TOO FAR SOUTH/EAST. INSTEAD THE STORM MOVES OUT TO SEA
INSTEAD OF UP THE COAST.

SURFACE TO 850 THICKNESS AND 850 TEMPS ARE ON THE WET SIDE OF THE
RAIN/SNOW THRESHOLD...JUST BARLEY...AND RH VALUES ARE LOW. GUIDANCE
NOT SHOWING MUCH FOR POPS...BUT THIS COULD ALL CHANGE. IT IS
CONCEIVABLE THAT THE PRECIP SHIELD COULD SPREAD FARTHER WEST. PRECIP
FALLING INTO THE DRIER AIR WOULD BE ENOUGH TO COOL CONDITIONS ENOUGH
FOR THE FORMATIONS OF FREEZING RAIN/SLEET/SNOW. AT THIS TIME THINK
CHANCES OF ANY PRECIP...LET ALONE FROZEN PRECIP...ON SUNDAY/MONDAY
ARE MINIMAL.

HIGH BUILDS OVER THE CAROLINAS DURING THE FIRST PART OF NEXT WEEK
WITH THICKNESS VALUES...AND TEMPERATURES...STARTING TO INCREASE BY
MID WEEK.

[jimvb]

LarryWx noticed a "northward" development in the GOM low that threatens the SE coast. But does it? I have been collecting GFS images over the past couple of weeks and run animations on them, either right on the NCEP site or on my local computer using Paint Shop Pro 8 animation. The most obvious animation is to fix an origin date, say 2004 December 24 00Z and then run the prediction into early 2005 by increasing the prediction date but keeping the origin date fixed at 2004/12/24/00.

But one could go the other way too. How about fixing a prediction date, such as 2004/12/26/06 Z and then varying the origin date? In such an animation, at about two weeks out, the storms and other features would bounce all over the place on the map, meaning there is not much confidence in these forecasts. But as the time gets closer and closer to 2004/12/26/06Z, the maps steady and vary less and less, and the whomping all over the place dwindles down to a gentle tremor. Eventually it terminates with the 0-hour map on 2004 December 26 06Z.

But not in this case. Sure, the maps steady, but if you try this out, you will notice a storm development over Florida and the SE coast. Not only does this storm get darker and darker, it moves north a bit. It's as though it were running in real time and space, rather than in prediction space. The development of this storm does not represent an actual storm developing but instead represents an anomaly in our being able to predict the future. If this anomaly proceeds from what I see of it in the animation, it will start heading up my way, into Virginia, and give us a snowstorm late on Yuletide Day!