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Jan 25/26 Storm Threat...(Part 3)


Marion_NC_WX

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.LONG TERM /TUESDAY THROUGH SATURDAY/...AS OF 315 AM SUNDAY...OVERVIEW...RAH NWS RALEIGHMOST MODEL GUIDANCE CONTINUES TO TREND SLOWER AND WESTWARD WITH THEMAIN STORM TRACK LATE TUESDAY INTO WEDNESDAY IN THE SOUTHEASTERNUNITED STATES. GIVEN THAT THE MID/UPPER LEVEL TROUGH IS FORECAST TOCUT OFF OVER MS/AL TUE-TUE NIGHT... THE MORE WESTWARD AND SLOWERSURFACE LOW DEVELOPMENT SOLUTIONS SEEM TO BE A GOOD FIT. CONFIDENCEIS ALSO INCREASING AS THE ENVELOPE OF SOLUTIONS CONTINUE TO NARROWWITH TIME. THE 00Z/ECMWF SOLUTION CONTINUES TO BE VERY CONSISTENTFROM RUN TO RUN ALBEIT A BIT SLOWER IN TIME... AND IT MAINTAINS AMORE COASTAL TRACK. THE ECMWF WILL BE GIVEN A BIT MORE WEIGHT GIVENITS BETTER PERFORMANCE TRACK RECORD IN THE PAST FEW WEEKS. HPCPREFERS A BLEND OF THE MODELS WHICH IS GENERALLY VERY CLOSE TO THECURRENT ECMWF SOLUTION... BUT SLIGHTLY INLAND WITH THE SURFACE LOWTRACK. ALL THIS MEANS MORE RAIN AND A BIT WARMER FOR CENTRAL ANDEASTERN NC. IT SHOULD ALSO BE NOTED THAT THE MID/UPPER LEVEL CUT OFFLOW WILL FOLLOW THE SURFACE LOW LATE TUESDAY INTO WEDNESDAY. THETRACK/STRENGTH OF THIS FEATURE WILL ALSO PLAY A ROLE IN P-TYPE LATETUE NIGHT THROUGH THE END OF THE PRECIPITATION EVENT WEDNESDAY. INADDITION... THE MID LEVEL DRY SLOTTING WILL PLAY A ROLE IN THE QPFAS WELL. CURRENT MODEL SOLUTIONS SUGGEST THAT THE MID/UPPER LOWTRACK WOULD BE FROM NEAR GSP TO FAY TO ECG WED. THIS WOULD MEAN APOTENTIAL CHANGE OVER TO SNOW ALONG AND LEFT OF THIS TRACK... WITH AWINDOW OF 4-6 HOURS OF HEAVY SNOW POTENTIAL IF CURRENT MODELPROJECTIONS HOLD. VERY LITTLE ADDITIONAL QPF IS EXPECTED SE OF THETRACK OF THE MID LEVEL LOW.DETAILS...GIVING SLIGHTLY MORE WEIGHT TO THE ECMWF BUT BLENDING THE LATEST00Z/NAM... 00Z/UKMET... AND 00Z/GEFS MEAN SOLUTIONS AS STATED ABOVEWOULD MEAN A SURFACE STORM TRACK EITHER ALONG THE COAST OR JUSTINLAND TUESDAY NIGHT THROUGH WEDNESDAY... WITH A SURFACE LOW AROUNDOR NEAR (998 MB NEAR SAV 06Z/WED... 994 MB NEAR EWN 12Z/WED... AND988 MB OFF DELMARVA 18Z/WED. THE MID/UPPER LOW SHOULD TRACK FROMCENTRAL AL (5400 DM) 06Z/WED TO NEAR GSP/CAE 12Z/WED TO ECG (AROUND5340 DM) 18Z/WED.THE STRONG DEEP COLD DRY RIDGE IS FORECAST TO BE PROGRESSIVE ANDMOVE OFFSHORE MONDAY NIGHT AND TUESDAY AS A COASTAL TROUGH FORMSNEAR THE COAST. THIS IS IMPORTANT IN THAT THERE IS NO SUPPLY OF COLDDRY AIR COURTESY OF A CAD HIGH TO OUR NORTH AS THIS STORM MOVES IN.THERE WILL STILL BE SOME COLD DRY AIR IN PLACE AS THE STRONG WARMAIR ADVECTION AND ISENTROPIC LIFT INDUCE PRECIPITATION BEGINNING INTHE SOUTHERN ZONES LATE MORNING OR EARLY AFTERNOON OVERSPREADING ALLOF THE REGION BY LATE AFTERNOON. THERMAL PROFILES AND FORECAST LOWLEVEL THICKNESSES NOW SUPPORT RAIN AS THE MAIN P-TYPE. THIS MAY BETRUE EVEN IN THE FAR NW PIEDMONT ZONES AS THE MID LEVEL WARMINGOVERWHELMS THE LAYER AS THE MODELS SUGGEST THAT THIS SYSTEM WILLREALLY WIND UP... WITH STRONG WAA FROM THE SE.JUST HOW FAR NW THIS WARMING GETS IS STILL IN QUESTION BUT EVEN THECOLDEST MODEL (THE ECMWF) NOW SUGGESTS 850-700 THICKNESSES WILLREACH INTO THE 1560S AS FAR NW AS GREENSBORO BETWEEN 00Z AND 06ZWEDNESDAY... WITH 1000/850 PARTIALS RISING TO AROUND 1310M. MORELIBERAL WARMING MODELS SUGGEST 1580S/1340S TO RDU! THEN THE MIDLEVEL THICKNESS CRASH BETWEEN 12Z AND 18Z WED WITH THE APPROACH OFTHE MID/UPPER LOW. THEREFORE THE P-TYPE NOMOGRAMS AND THERMALPROFILES SUPPORT RAIN TO DEVELOP TUESDAY... WITH RAIN CONTINUINGTUESDAY NIGHT. THE RAIN MAY CHANGE TO SNOW IN THE NW AND NORTHCENTRAL WEDNESDAY BUT THIS WILL BE HIGHLY DEPENDENT ON THETRACK/STRENGTH OF THE MID/UPPER LOW. THE MILLER A STORM SUPPORTS AVERY NARROW RAIN/SNOW LINE (AND THIS CASE STRONGLY SUGGESTSELEVATION WILL PLAY A MAJOR ROLE). THIS STORM FAVORS HEAVY SNOW FORTHE MOUNTAINS (BOTH SYSTEM AND UPPER LOW)... WITH THE POTENTIAL INTOTHE FOOTHILLS AND FAR NW PIEDMONT (WITH TRACK OF UPPER LOW).ELSEWHERE... RAIN. THE RAIN MAY CHANGE TO SNOW BEFORE ENDINGWEDNESDAY OVER THE REST OF THE PIEDMONT AND NORTHERN COASTAL PLAIN.QPF APPEARS MODERATE TO LOCALLY HEAVY WITH OVER AN INCH POTENTIAL.THE DRY SLOT WILL HAVE TO BE CONSIDERED (NOW FAVORING THE EASTERNZONES AFTER 06Z WED... WITH ADDITIONAL BUT LIGHTER QPF WITH THEUPPER LOW WEDNESDAY.WHAT MAY GO WRONG...IF THE SYSTEM IS FASTER AND WEAKER... THEN ITWOULD BE LESS WOUND UP (LESS MID LEVEL WARMING) AND THE SURFACE LOWTRACKS JUST OFFSHORE... THEN THE SNOW THREAT WOULD COME BACK TO THENW PIEDMONT EARLY ON. IN ADDITION... A CHANGE TO HEAVY SNOW MAYSTILL BE A CONCERN MAINLY FROM THE TRIAD TO ROXBORO... IF THEMID/UPPER LOW DO TRACK FROM GSP TO FAY TO ECG WEDNESDAY. THIS WILLHAVE TO BE WATCHED CLOSELY.Snowman.gif smile.gif gun_bandana.gif

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well we can throw anything that the NAM or the GFS says out the window for now...they have no idea what this storm will do...the euro on the other hand...

The NWS seems to think the GFS is god enough to base an entire forecast on....

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE NASHVILLE TN

412 AM CST SUN JAN 23 2011

.DISCUSSION...WEAK H5 WAVE OVER THE PLAINS MOVING INTO THE AREA.

SHOULD BRING A MIX OF RAIN AND SNOW FOR THE NW QUAD OF THE

MIDSTATE THIS AFTERNOON. CHANCE OF PRECIP WILL CONTINUE FOR

TONIGHT AS THE AXIS OF THE WAVE MOVES THROUGH. MORE OF A CHANCE

FOR SNOW WITH THE COLDER TEMPS TONIGHT...MAINLY IN THE NORTH

AND PLATEAU.

A FRONTAL TROUGH WILL MOVE TOWARD THE MIDSTATE ON MON WITH A LOW

PRESSURE SYSTEM FORMING IN THE GULF OF MEXICO MON NGT. THIS WILL

CONTINUE CHANCE POPS FOR MON AND MON NGT. AGAIN...THIS WILL BE A

MIX OF RAIN AND SNOW DEPENDING ON THE TIME OF DAY. THE LOW OVER

THE GULF UNDERGOES SIGNIFICANT DEVELOPMENT ON MON NGT AND IT

BEGINS TO MOVE ENEWD. MOISTURE ASSOCIATED WITH THE LOW PUSHES INTO THE

MIDSTATE INCREASING POPS FOR THE MON NGT THROUGH TUE NGT TIME FRAME.

GFS AND EURO ARE IN BETTER AGREEMENT ON THIS SYSTEM WITH THE GFS

USING A MORE NLY TRACK. THE MAIN DIFFERENCE BETWEEN THIS SYSTEM

AND THE PREVIOUS SYSTEM THAT DROPPED SIGNIFICANT SNOWFALL OVER THE

AREA IS THIS...THERE IS NOT A STRONG COLD AIR MASS IN PLACE TO THE

NORTH OF THE LOW. AS A RESULT TEMPERATURES IN THE LOWER LAYERS WILL

CAUSE A DIURNAL CHANGE IN PRECIP TYPE. THUS TUE AM WILL START OFF

WITH A MIXED RAIN AND SNOW PATTERN THEN TRANSITION TO NEARLY ALL

RAIN IN THE AFTERNOON. ON TUE NGT...THE LOW PASSES TO THE EAST OF

THE AREA...ALLOWING MORE COLD AIR TO PUSH INTO THE MIDSTATE. THIS WILL

TRANSITION THE PRECIP QUICKLY BACK TO SNOW. THUS IT LOOKS LIKE TUE

NGT WILL BE THE BEST CHANCE FOR ANY ACCUMULATING SNOW. BEST GUESS

ATTM IS AROUND AN INCH IN THE SOUTH AND PLATEAU. HOWEVER...ALL OF

THIS IS HIGHLY DEPENDENT ON THE TRACK OF THE LOW.

SNOW SHOWERS TAPER OFF ON WED IN THE EAST WITH FLURRIES POSSIBLE

ON THU AS ANOTHER UPPER WAVE SWINGS THROUGH...BUT MOST MOISTURE IS

WELL TO THE EAST.

A FEW MORE SNOW SHOWERS POSSIBLE FOR SAT NGT AS THE TAIL END OF

ANOTHER WAVE SWEEPS THE TN VALLEY.

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Amen to that.

Still anyones game, lol.

[quote name=weathertree4u'

timestamp='1295784041' post='342316]

At this point, I would appreciate to see a back-to-back model run of any model that shows the same solution

GFS is going south and east....

GFS 00 @90

gfs_pcp_090s.gif

GFS06 @84

gfs_pcp_084s.gif

00NAM @84

nam_pcp_084s.gif

06NAM @84

nam_pcp_084s.gif

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:facepalm: at the GFS this morning...model madness is going to rule until Tuesday it looks like.

Looks like those highs Wow and I have been banking on are starting to show their teeth again. The 6z GFS and to some extent the NAM do not have a clue again and are catching up. This thing is not over yet. Man...the suspense dude!

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Good morning. Even though the 6z GFS went way south and east, it's ensemble members did not. They are VERY GOOD AGREEMENT with each other. The low is very strong and most come inland between Wilmington and Cape Hatteras in NC. Almost all give on average >.75 qpf along the track of the storm which includes all of GA, SC, NC. There will be alot of something falling. To me it looks like it will be an I-77 special with a chance for 1-2 inches east of the mountains as the storm wraps up. BTW the bickering in the SE forum last night was terrible. Looks like you all were missing Foothills. Let's see what today brings!

storm total precip from 6z GFS members

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Obviously, quite a shift from the 0z to the 6z GFS, and the reason is the handling of the 500mb features. I think a big culprit is the handling of the little disturbance digging in behind our main disturbance/ ULL. Notice how much weaker 'our' system is on the 6z compared to the 0z at the same time.

0z

post-390-0-31346300-1295786842.gif

6z

post-390-0-36945300-1295786940.gif

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Ok, so if I am seeing and reading right. The Euro still has the storm but the temps are going to be the problem. It also looks like the storm has possibly slowed down again since it looks like it may still be in TX on Tuesday. Just looking ATL looks like cold rain with no possibility of winter mix. Mt of N GA might get some snow but that even looks to be a big questions as it stands right now. I got lost on the Euro pbp. Matt thanks for your post and update on your blog. This may come down to a nowcast since the models just can't seem to get it together. We have seen this happen many times. :)

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HPC FD for day 3 posted @ about 5:00 AM

http://www.hpc.ncep.noaa.gov/wwd/winter_wx.shtml

DAY 3...

SOUTHEAST/SOUTHERN APPALACHIANS...

STRONG SHORTWAVE MOVING THROUGH THE CENTRAL PLAINS WILL CONTINUE

TO CARVE OUT A DEEP UPPER-LEVEL TROUGH AND DEVELOP A H5 LOW ACROSS

THE LOWER MISSISSIPPI VALLEY ON TUESDAY NIGHT AND MOVE EASTWARD

ALONG THE I-10/I-20 CORRIDOR TO THE SC/GA LINE BY WEDNESDAY

MORNING. SURFACE WAVE DEVELOPING IN THE WESTERN GULF OF MEXICO AND

ASSOCIATED LOW-LEVEL SOUTHERLY FLOW COMPONENT WILL PROVIDE THE

MOISTURE AND UP GLIDE NECESSARY TO BRING A MIXED PTYPE

EVENT...INCLUDING ACCUMULATING SNOWFALL TO THE TENNESSEE

VALLEY...PORTIONS OF NORTHERN MS/AL AND GA. THERMAL PROFILES AND

FRONTOGENESIS PROGS SUGGEST SEVERAL BANDS OF WINTER PRECIPITATION

WILL MIGRATE ACROSS THE REGION...NORTH OF THE H5 LOW TRACK WITH

RAIN CHANGING TO FREEZING RAIN...SLEET AND SNOW FROM SOUTH TO

NORTH TUESDAY MORNING ACROSS MISSISSIPPI AND ALABAMA. COLD-SECTOR

PRECIPITATION APPEARS TO BE IN FULL SWING TUESDAY EVENING THROUGH

EARLY WEDNESDAY MORNING ACROSS PORTIONS OF TENNESSEE...NORTHEAST

MISSISSIPPI/NORTHERN ALABAMA...NORTH GEORGIA AND THE SOUTHERN

APPALACHIANS AS DEFORMATION CLOUD SHIELD BEGINS TO FORM ALONG THE

NORTHWEST QUADRANT OF THE H5 CIRCULATION. SOME OF THE DETAILS

ASSOCIATED WITH THE RAPIDLY-DEEPENING SURFACE WAVE STILL HAVE TO

BE SORTED OUT SOUTH OF I-20...PARTICULARLY WITH THE THREAT OF

FREEZING RAIN/SLEET ACCUMULATIONS AND THE STRENGTH/DEPTH OF THE

LOW-LEVEL FLOW. HOWEVER...THERE IS GOOD AGREEMENT FROM H85 TO H5

WITH THE THERMAL PROFILES AND POST-FRONTAL COLD AIRMASS INTRUSION

ACROSS THE SOUTHEAST. CURRENT COLD-SECTOR PRECIPITATION FORECASTS

SUGGEST A BROAD SWATH OF 2-4 INCHES OF SNOWFALL ALONG AND NORTH OF

I-20. FOR NOW...MANUAL GRAPHICS DEPICT THE EVENT AS A

SLIGHT/MODERATE RISK OF 4+ INCHES ACROSS PORTIONS OF NORTHEAST

MISSISSIPPI...SOUTHERN TENNESSEE...NORTHERN ALABAMA...NORTHERN

GEORGIA. PORTIONS OF THE MOUNTAINS OF SOUTHWESTERN NORTH CAROLINA

AND NORTHWEST SOUTH CAROLINA ARE EXPECTED TO START RECEIVING

SIGNIFICANT SNOWFALL LATE TUESDAY NIGHT INTO WEDNESDAY MORNING.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

VOJTESAK

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I have a question that hopefully someone with a little more experience can shed some light on. If the eventual track ends up anywhere close to the GA/SC/NC coast would the gulf stream not interact with the storm causing the storm to actually jog a little more east than what the models think?

I'm curious on this because the gulf stream is such a force I would think the natural tendency of a LP would be to move along it becuase that is where the best moisture and warm water is (the food for the storm so to speak).

Just curious so any thoughts are appreciated while things are a little slow this morning.

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I have a question that hopefully someone with a little more experience can shed some light on. If the eventual track ends up anywhere close to the GA/SC/NC coast would the gulf stream not interact with the storm causing the storm to actually jog a little more east than what the models think?

I'm curious on this because the gulf stream is such a force I would think the natural tendency of a LP would be to move along it becuase that is where the best moisture and warm water is (the food for the storm so to speak).

Just curious so any thoughts are appreciated while things are a little slow this morning.

I'm not an expert, but my experience says no. The track of such a lp system is going to be primarily driven by the track of the H5 flow/cutoff low.

Sometimes the Gulf Stream can play a part in the location of cyclogenesis off the SE coast, in conjunction with other mid/upper level features. But by and large the surface low track is not going to be influenced by the Gulf Stream.

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Although NWS has went from all snow they still give me a little hope of a mix....

TUESDAY...PARTLY SUNNY WITH A SLIGHT CHANCE OF RAIN AND SNOW IN

THE MORNING...THEN MOSTLY CLOUDY WITH RAIN AND SNOW LIKELY IN THE

AFTERNOON. LITTLE OR NO SNOW ACCUMULATION. HIGHS IN THE LOWER

40S. LIGHT AND VARIABLE WINDS. CHANCE OF PRECIPITATION

60 PERCENT.

.TUESDAY NIGHT AND WEDNESDAY...SNOW AND RAIN. LOWS IN THE LOWER

30S. HIGHS IN THE UPPER 30S. CHANCE OF PRECIPITATION 80 PERCENT.

.WEDNESDAY NIGHT...MOSTLY CLOUDY. SNOW IN THE EVENING. LOWS IN

THE UPPER 20S. CHANCE OF SNOW 80 PERCENT

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