A FLURRY (or more) of ACTIVITY February 1st?

[Reneezelle]

I can't read a street map let alone these! Give me some English! Is it good or bad???!!!

[snowdog]

Hah, I have no idea what I was looking at on that SREF map.  I'm guessing it was supposed to be good?

[Nashville_wx]

That was a link to the SREF. Most recent model run. You can then choose from a list what you want to see. I was looking at 3Hr max snowfall.

[Eric]

I can't read a street map let alone these! Give me some English! Is it good or bad???!!!

LOL!

[Nashville_wx]

Well looks like the the forecast for BNA has changed as I figured it would. 100% Rain/Snow thursday night with low of 33F. Friday High of 39 with Rain/Snow in the AM. Tonights model runs hopefully show some agreement. Current thinking is a Track up through the Jackson Tn Area. Euro is pretty much in the middle so its my model of choice right now. Once the Nam gets a little closer in we can start taking its input more seriously. But main consensus is to make the L up through the memphis area.

[Nashville_wx]

For those who understand it



 
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
212 PM EST TUE JAN 29 2008
 
VALID 12Z FRI FEB 01 2008 - 12Z TUE FEB 05 2008
 
12Z ECMWF UPDATE...
WELL...THE 12Z ECMWF HAS TRENDED SIMILARLY TO THE GFS WITH THE SYS
DROPPING SWD THRU THE E PAC TO THE W COAST EARLY IN THE PD...GOING
FOR A WEAKER SOLN.  THIS SOLN HAS FLATTENED THE FLO SOMEWHAT OVER
THE CONUS AND LEAD TO A FASTER OVERALL SOLN.  CONFIDENCE IN THE
12Z ECMWF DECREASES CONSIDERABLY BY D6/MON AS THE NEW RUN RAPIDLY
DEEPENS THE SYS OVER THE UPR MS VLY/GRTLKS...AND WHILE THE GFS
ALSO CARRIES A DEEPER SOLN THAN THE PREVIOUS PROGS
HERE...CONFIDENCE IS LOW AS ONLY 2 12Z NCEP ENS MEMBS ARE NEARLY
AS DEEP AS THE GFS OR ECMWF WITH THE LOW BY D7/TUE.  ONLY HEDGED
THE PROGS TOWARD THE 00Z ECMWF A BIT OVER THE PREVIOUS CAN GLOB
BLEND USED FOR THE 12Z MODEL UPDATE ON D3/FRI - D5/SUN.


12Z MODEL UPDATE...

THE 12Z GFS DAMPENS THE SHRTWV SYS DROPPING THRU THE ERN PAC AND
INTO THE W COAST D3/FRI AND D4/SAT MORE THAN THE 00Z GFS OR THE
12Z CAN GLOB AND UKMET.  GIVEN THIS...CONFIDENCE DECREASES IN THE
12Z GFS FROM D4/SAT ONWARD AS THIS SYS AMPLIFIES THE UPR PATTERN.
THE CAN GLOB AND UKMET STILL SUPPORT SOME SORT OF WAVE PASSING
NEWD FROM THE CNTRL PLAINS INTO THE GRTLKS D3/FRI THRU
D5/SUN...BUT THEY ARE NOT AS AMPLIFIED AS THE PREVIOUSLY PREFERRED
00Z ECMWF FOR THAT TIME-FRAME.  BLENDED MORE CAN GLOB INTO THE MIX
WHICH SHUD ALLOW FOR A SLIGHTLY WEAKER SYS HERE AND A SLIGHTLY
MORE PROGRESSIVE SOLN WITH THE SYS PASSING THRU THE OH VLY AND
NORTHEAST D3/FRI AND D4/SAT THAN THE EARLIER HPC PROGS.  FEAR THE
00Z ECMWF MAY BE TOO SLOW BASED ON THE LATEST GUIDANCE CONSIDERING
NONE OF THE 12Z NCEP ENS MEMBS SUPPORT A SOLN AS SLOW AS THE 00Z
ECMWF. 



PRELIM MEDR UPDATE...
THE LATEST GUIDANCE DOES NOT PROVIDE ANY REASON TO CHANGE THE
EARLIER REASONING.  THE 00Z ECMWF ENS MEAN AND THE 06Z NCEP ENS
MEAN CONTINUE TO SUPPORT A SLOWER/MORE SLY SOLN LIKE THE ECMWF
OVER THE 00Z/06Z GFS WITH THE SYS PASSING THRU THE 0H VLY AND E
COAST D3/FRI AND D4/SAT.  CONFIDENCE STILL REMAINS LOW IN THE W BY
D5/SUN AS THE ECMWF FLATTENS THE FLO OVER THE E PAC MORE THAN ITS
ENS MEAN AND MOST OF THE OTHER GUIDANCE...SENDING THE H5 TROF THRU
THE W AND INTO THE PLAINS MORE RAPIDLY.  THE PREVIOUSLY USED BLEND
WITH THE NAEFS STILL APPEARS REASONABLE.



EARLY PRELIM MEDR DISCUSSION...

TELECONNECTIONS WITH A POSITIVE ANOMALY MOVING PAST 40N 158W
FAVORS A POLAR VORTEX IN EXTREME NORTHERN CANADA AND TROUGHING IN
THE WEST.  THE MODEL SUITE DISPLAYS THESE IDEAS...AND IS IN
GENERAL AGREEMENT EVEN ON SOME OF THE DETAILS.  THE 00Z
GFS...HOWEVER...IS A FAST OUTLIER WITH THREE SYSTEMS /THE ONE
MOVING THROUGH THE EAST EARLY...THE NORTHERN PLAINS/GREAT LAKES
MID PERIOD...AND THE NORTHEAST PACIFIC SOUTH OF THE GULF OF ALASKA
LATE IN THE PERIOD/.  SINCE THE 00Z GFS HAD LITTLE ENSEMBLE
SUPPORT FROM THE ECMWF/CANADIAN/NCEP ENSEMBLE MEMBERS...CHOSE NOT
TO USE IT.  THE 00Z ECMWF...HOWEVER...HAS THE GENERAL SUPPORT OF
THE VARIOUS ENSEMBLE MEANS...AND WAS USED OUTRIGHT INTO EARLY THIS
WEEKEND.  THEREAFTER...IN ORDER TO HELP RESOLVE SMALLER
DIFFERENCES AMONGST THE REMAINING GUIDANCE LATE IN THE
PERIOD...CHOSE TO COMPROMISE BETWEEN THE 00Z ECMWF AND THE 28/12Z
NAEFS BIAS-CORRECTED ENSEMBLE MEAN WHICH SPLIT THE DIFFERENCE
BETWEEN THE 00Z ECMWF AND 00Z NCEP ENSEMBLE MEAN.



REGIONAL HIGHLIGHTS...

...WRN CONUS...
A SERIES OF PAC SYSTEMS SHUD PLOW THRU THE W THIS PD.  XPCT A WET
PD OVER MUCH OF THE NW.  THE LONGWAVE TROF OVER THE W SHUD AMPLIFY
CONSIDERABLY D4/SAT - D5/SUN...WITH PCPN AND COOLER TEMPS XPCTD TO
PUSH INTO THE FOUR CORNERS STATES D5/SUN - D6/MON. 

...CNTRL CONUS...
XPCT A REASONABLY DRY PD OVER MUCH OF THE REGION THRU MID DAY
5/SUN WHEN THE AMPLIFYING WRN TROF PUSHES ITS WAY INTO THE
ROCKIES...DIRECTING SLY RETURN FLO OUT OF THE GOMEX THRU PLAINS/MS
VLY.  XPCT PCPN TO ORG ALONG THE SLOW MOVING BNDRY XPCT TO STRETCH
FRONT EH SRN PLAINS INTO THE GRTLKS D6/MON - D7/TUES.

...ERN CONUS...
AFTER THE D3/FRI - D4/SAT SYS BRINGS SOME SNOW TO PORTIONS OF THE
OH VLY AND NORTHEAST AND THE POTENTIAL FOR SEVERE WX OVER THE SE
ON D3/FRI...LOOK FOR THE REGION TO REMAIN RELATIVELY WARM AND DRY
THRU LATE D6/MON WHEN THE SLOW MOVING SYS INTO THE MS VLY EDGES
EWD AND BRINGS SOME PCPN IN FROM THE W.

CLARK/ROTH




Last Updated: 212 PM EST TUE JAN 29 2008

[Nashville_wx]

Latest from nws Nashville.

Thursday Night: Periods of rain, mixing with snow after midnight. Some thunder is also possible. Low around 33. East wind around 15 mph becoming west southwest. Winds could gust as high as 25 mph. Chance of precipitation is 100%.


Friday: A chance of rain and snow showers. Mostly cloudy, with a high near 38. West wind between 10 and 15 mph, with gusts as high as 25 mph. Chance of precipitation is 30%.


It looks like Fridays high now is 38degrees. We still have a low of 33 degree which could go below or above forecast numbers. Friday depending on the exact track of the

850MB low ( shown below )



Temps could go above or below 33 degrees. As always we need to 850mb low to track south of the nashville area.

66Hours NAM





72 Hours NAM

[Nashville_wx]

Given the 850mb temps will right around 0C @ 850 around 12:00Am - 1:00 Am Friday. Precip falling from there on should be in a form of Mix/Snow depending on temp structure. My basic thinking is Friday night we will change over to snow in the later hours of the night. Accumulations are hard to even talk about. Given that temps do support snowfall, intensity will depend on accumulations as well as the amount of moisture left. Look at it this way, until we become more certain that the track does not move NW, we will see a MIX thursday night through Friday morning, Little or no snow accumulations, but maybe some nice stuff flying in the air depending on the layers. If we have more of a Southeast move then things will become a bit more tricky. Precip changes over to snow faster and you are in a new game. Do not get excited nor frustrated till tomorrow eveing when we have a better idea.

[Nashville_wx]

Update.. Looking at the 12Z Gfs Bufkit data is shows 1.2" IP From 6Pm to 9pm . It could be from the dry  from 870mb down the surface  Then a snow chance of light precip which is shows in the form of snow.
Update:  18Nam bufkit = :{


Looking into the 18Z for trends I like what I see. If tonights runs slow the L pressure down ( and take a more neutral tilt) ( given 500mb) it may allow it to dig a bit farther southeast. Something to def watch. As for looking at the 12Z gfs data for tonight, not really confident we see any type of frozen accumulative precip.

[Nashville_wx]

My progress continues as we look at the latest info. I want to show everyone the latest SREF spread coming 00Z Fri through the extended. As you can see the farther we move in time the more spread each member has. You can use this info as a tool on how much the members agree and trends ect ect. This is actually prob but less agreement comes with more spread.

57 hours.



60 hours.



63 hours



66 hours



As you can see we have still have some uncertainty amount members.


63 hours Max 3 hour snowfall



66hour Max 3 hours snowfall



69 Hours




Just a look into the future using one tool avalible. Lets see how tonights run go and comment more on this.
Sorry for not explaining more but right now too many things can change.

[Nashville_wx]

Memphis sits in a nice location given the SREF.

[Nashville_wx]

18Z Gfs Ensembles

As you can see the OP run seems to have the -0C line close to us. Other member are west with some running close enough to the OP run. Given that the -0C line comes through nashville or shortly after we can go from that point forward to see how much actually precip will fall with condition favorable for snow.

OP RUN OF GFS



Ensemble  60 hours



Ensemble 66 hours

[Nashville_wx]

I am done posting maps for now. I will be back this even to post all the 00Z data updates and to discuss the chance for winter precip this weekend. 18Z Gfs Bufkit shows a start as snow to rain back to snow with accumulations ( small ). Lots to change and lots to talk about this evening

[Nashville_wx]

Well I had to post it, gosh I cant stop but this is worth posting

[Nashville_wx]