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First Week of March Nor'Easter

Capt. Adam

By Capt. Adam,
in Philadelphia Region

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hazwoper

hazwoper

Posted
Posted

Yeah Bliz, there was a second iteration that had even more widespread 4-6" amounts.

I think TWC call from this evening that Anthony showed is so poor. Terrible.

Must say I am intrigued by this norlun feature for thurs night/Friday that the nam is showing. Not sure if it will be snow or rain though??

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chubbs

chubbs

Posted
Posted

Getting a little more optimistic about the front-end out this way.. SREF, NAM, and GFS are pushing the initial strong band further N into S PA. Could be a quick several inches near daybreak in NE Md  and S Chesco and perhaps into N De+Delco. GFS/NAM/SREF qpf is in the 0.4-0.6" range  by 10 AM.

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cast4

cast4

Posted
Posted

Getting a little more optimistic about the front-end out this way.. SREF, NAM, and GFS are pushing the initial strong band further N into S PA. Could be a quick several inches near daybreak in NE Md and S Chesco and perhaps into N De+Delco. GFS/NAM/SREF qpf is in the 0.4-0.6" range by 10 AM.

yep I'm liking my lanco location for this one. Looks like we get some pretty nice waa bands early.
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blizzardlover

blizzardlover

Posted
Posted

Getting a little more optimistic about the front-end out this way.. SREF, NAM, and GFS are pushing the initial strong band further N into S PA. Could be a quick several inches near daybreak in NE Md  and S Chesco and perhaps into N De+Delco. GFS/NAM/SREF qpf is in the 0.4-0.6" range  by 10 AM.

SPC Meso -- wonder if this area will edge N & E and end up delivering the snow you mention above..

MESOSCALE DISCUSSION 0248

NWS STORM PREDICTION CENTER NORMAN OK

0952 PM CST TUE MAR 05 2013

AREAS AFFECTED...ERN WV...PORTIONS OF NRN/WRN VA...A LARGE PART OF

MD...WASHINGTON DC...PORTIONS OF FAR SRN PA

CONCERNING...HEAVY SNOW

VALID 060352Z - 060945Z

SUMMARY...SNOW WITH RATES OF 1-1.5 IN/HR WILL SPREAD NEWD ACROSS

PARTS OF THE MID ATLANTIC AND CNTRL APPALACHIANS OVERNIGHT.

DISCUSSION...AS THE LEADING EDGE OF A STRONG MID-LEVEL PV MAX

CONTINUES OVERTAKING A LOW-LEVEL BAROCLINIC ZONE OVER THE

CAROLINAS...A SFC LOW IS DEVELOPING ALONG THE ATTENDANT FRONT IN

CNTRL NC WHERE PRESSURE FALLS OF 3-4 MB PER 2 HOURS HAVE BEEN NOTED.

AS THE SFC LOW TRACKS NEWD/NWD DURING THE NEXT SEVERAL HOURS...A

STRENGTHENING 850-700-MB FRONTOGENETIC CIRCULATION WILL SUPPORT

INCREASING MESOSCALE ASCENT. IN TURN...PRECIPITATION WILL CONTINUE

TO OVERSPREAD THE AREA TONIGHT AMID AN ELEVATED WARM CONVEYOR BELT.

WHILE LOW-LEVEL THERMAL PROFILES ARE INITIALLY MARGINAL FOR SNOW

FROM THE DC AREA INTO NRN VA...THE COMBINED EFFECTS OF COOLING OWING

TO FORCED ASCENT AND WET-BULB/NOCTURNAL EFFECTS SHOULD AID IN

LOWERING WET-BULB ZERO HEIGHTS TOWARD THE SFC DURING THE NEXT FEW

HOURS. FURTHERMORE...ISALLOBARIC FORCING SHOULD ALLOW LOW-LEVEL FLOW

BACK AND BECOME MORE NLY...RESULTING IN COOLER AIR BEING DRAWN INTO

THE REGION. AS SUCH...SNOW WILL BECOME THE PREDOMINANT PRECIPITATION

TYPE ACROSS THE AREA BY 06Z...WITH SNOW RATES INCREASING TO 1-1.5

IN/HR THEREAFTER. LOCALLY HIGHER RATES MAY OCCUR IN UPSLOPE-FAVORED

AREAS AND RIDGETOPS OVER THE CNTRL APPALACHIANS. THESE RATES WILL

LIKELY SPREAD NEWD WITH TIME...ROUGHLY IN TANDEM WITH THE TRACK OF

THE LOW...REACHING THE DC AREA MORE LIKELY AFTER 08Z. THESE RATES

WILL LIKELY CONTINUE THROUGH DAWN.

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Absolute Humidity

Absolute Humidity

Posted
Posted

GEM might be further north... but judging by its temps, it doesn't have a lot of snow on it for PHL (or NYC)....  35 at 12Z, 37 at 18Z, 36 at 0Z, 35 at 6Z at both cities.

GGEM warm bias at play. I doubt most of that is rain, but hey, this is a horrible Philly winter were talking about. GGEM might be right thermally speaking.

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cast4

cast4

Posted
Posted

GGEM warm bias at play. I doubt most of that is rain, but hey, this is a horrible Philly winter were talking about. GGEM might be right thermally speaking.

 

Yeah, I know that the precip map algorithms of the GGEM are always very inaccurate. Other than that I'm not sure. For some odd reason the Ukie also went very far north as well bringing 25 mm into the city.

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wolfie09

wolfie09

Posted
Posted

mount holly 917 pm

 

 

 

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...HOPING A RESEARCH PROJECT COMES OF THIS EVENT AS THERE ARE SOMANY CONFLICTING SIGNALS STILL IN OUR CWA WE DONT KNOW WHERE TOSTART. CAN UNDERSTAND WHY SPRING EQUATIONS ARE CAUSING PROBLEMSWITH MOS GUIDANCE, BUT THE MODELS KEEPING SFC TEMPS WELL ABOVEFREEZING INTO EARLY WED EVENING EXCEPT FOR THE WRF-NMMB WHICHDYNAMIC COOLS TO NEAR FREEZING.WELL AS FOR PCPN VERIFICATION THROUGH 00Z. ALL OF THE MODELS HAD AGOOD HANDLE ON THE AREA PF EXCELLENT MID LEVEL QVEC CONVERGENCEEMANATING FROM THE SFC LOW INTO IL. SINCE MOST OF THIS FELL ASSNOW HARD TO SAY IF THEY WERE WET OR DRY, BUT THE PLACEMENT WASGOOD. WHERE IT WAS RAIN FARTHER TO THE SOUTH, THE CAN GGEM SEEMEDTO VERIFY THE BEST. A BUNCH OF MODELS WERE TOO WET IN SC AND GA,DON`T KNOW IF THIS WAS JUST BEING TOO FAST WITH DEVELOPINGCONVECTION AS THE FRONT IS NOT SLOW AND THERE IS CONVECTION NOW.THE MODELS ARE SLIGHTLY TOO SLOW WITH THE BACK EDGE, WRF-NMMB MOSTGUILTY PARTY. AS FOR THE SFC LOW ITSELF, THE 18Z WRF-NMMB VERIFIEDTHE BEST. ALSO GOOD WITH BAGGINESS OVER WRN NC. ECMWF 2ND BEST,CORRECT LATITUDE, JUST SLIGHTLY SLOW, NOTHING NEW THERE. 00Z RUCNOT GOOD, SFC LOW IS NOT IN OH YET AS 01Z. CAN SEE A CIRCULATIONFORMING AROUND CLT AT 02Z. RAIN/SNOW LINE OUTSIDE OF THE MOUNTAINSWAS AROUND 1295M 1000-850MB NAM THICKNESS.AT 925MB IN THE LOCAL AREA ALL OF THE MODELS WERE TOO COLD, THEWRF-NMMB 6HR FCST AMONG THE COLDEST SOMETIMES BY 2 OR 3C. GFS BESTOVERALL. BOTH BWI AND PHL ACAR FREEZING LEVEL IS CURRENTLY 2500FEET. THIS MAY ALL BE A MOOT POINT AS THERE IS PLENTY OF DRY AIRBETWEEN 925MB AND SFC ON THE 00Z SOUNDINGS. IF ANYTHING, THEMODELS TOO MOIST TOO FAST AT IAD LOOK GOOD AT WAL. AT 850MBCONVERSELY THE MODELS ARE TOO WARM BY AROUND A DEGREE OR SO, THEECMWF OVERALL THE BEST. AT 500MB THERE IS MORE RIDGING OVER THECAROLINAS AND THE CLOSED LOW LOOKS TO BE DIGGING MORE. THE BNAHEIGHT AND TEMPERATURE FORECASTS ARE LAGGING BEHIND.THE LATEST SREF EMPHASIZING TWO AREAS AS BEST POTENTIAL FOR HEAVY(WARNING CRITERIA) SNOW. ONE WHERE CURRENT WARNING IS IN EFFECT,THE SECOND MAX MAY BE IN OCEAN AND MONMOUTH. SREF QPF ISAPPROXIMATELY 50 TO 75 PCT OF OPERATIONAL 18Z WRF-NMMB.WOULD THINK THE 500MB FCST SHORTFALLS WOULD RESULT IN A SHARPERTURN WITH THE 00Z MODEL RUN. AS FOR CHANGES WITH THIS SHORT TERM,BASED ON THE PREV RUC AND HRRR, WE ADDED SOME MORE SNOW TO OUREASTERN SHORE OVERNIGHT. THE TOP DOWN PROCEDURE WE DID WITH THEPREVIOUS UPDATE WAS ALL RAIN. LOOKS LIKE A SHOT OF SNOW FOR MAYBEAN HOUR OR SO WHEN INTENSITY INCREASES LATER. ANY ADJUSTMENTS TOTEMPERATURES WERE BASED ON CURRENT OBS. ITS COLDER TOWARD THECOAST CURRENTLY THAN INLAND. WOULD THINK ONCE THE WINDS START ANDCLOUDS ARRIVE, THEY WILL BUMP UP.

 

 

 

 

http://forecast.weather.gov/product.php?site=NWS&issuedby=PHI&product=AFD&format=CI&version=1&glossary=1&highlight=on

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famartin

famartin

Posted
Posted

Yeah, I know that the precip map algorithms of the GGEM are always very inaccurate. Other than that I'm not sure. For some odd reason the Ukie also went very far north as well bringing 25 mm into the city.

Huh?  I don't even see half that on the UKMET, from what I'm looking at.  Where r you looking?

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mookiemike

mookiemike

Posted
Posted

Looks like a lot of qpf wasted on a cold rain and some sleet. Thermal profile has boundary level issues until some unknown point late afternoon Wednesday to as late as evening in Metro Philly, where I am. Any accumulating snow seems relegated to this time period, and the wave on Thursday evening which looks to affect the northern area of our coverage area.

 

Gale force NE winds, but it is March when the elements come together. Well, it makes it one step better than 2011, so enjoy whatever comes our way. I'm waiting till new guidance comes out early morning, as this is going to be a combination of now casting and mesoscale forecasting, but I'm prepared for a slushy 1-2". Just keeping it real.

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wolfie09

wolfie09

Posted
Posted

Nam being disregarded as u would expect..

 

Mount holly

 

 

 

FTER DAYS OF ANTICIPATION, THE STORM THAT HAS BEEN WELL DISCUSSED,BUT NOT NECESSARILY WELL MODELED IS BEGINNING TO IMPACT THE AREA.LATEST RADAR IMAGERY SHOWED PRECIP, MAINLY IN THE FORM OF RAINAFFECTING TH MD ERN SHORE AND SRN AND CNTRL DE ATTM.  IT WASBEGINNING TO MOVE INTO EXTREME SRN NJ AS WELL.  TEMPS HAVE ACTUALLYRISEN A BIT ACRS THE ERN SHORE OF MD AND IN DE ERLY THIS MRNG.  ITAPPEARS AS THAT THE AREAS WHERE PRECIP IS FALLING HEAVIER, IT ISLIQUID AND WHERE IT IS LIGHTER (AKA TO THE W CURRENTLY), IT IS SNOW.NORMALLY, AS WE GET CLOSER TO THE EVENT, CONFIDENCE INCREASES.HOWEVER, THIS IS ONE OF THOSE ANOMALOUS EVENTS, WHERE THAT IS NOTNECESSARILY THE CASE.  WHILE OVERALL, THE MDLS HAVE A DECENT HANDLEON THE TRACK OF THE LOW, THERE ARE ENOUGH DIFFERENCES IN THEINDIVIDUAL DETAILS TO CONTRIBUTE TO INCREASED UNCERTAINTY.  THE NAMCONTINUES TO BE ABNORMALLY WET AND COLD AND IS BEING DISREGARDED. ITALSO TENDS TO STALL THE LOW OVER THE WATER FOR AN EXTENDED PD OFTIME.THE CMC AND GFS ARE IN DECENT AGREEMENT AND HAVE A BIT MORE NLY SOLNTHAN THE UKMET AND ECMWF WHICH ARE A BIT FURTHER S.  THE MORE SRNSOLNS WOULD MEAN LESS QPF, BUT A BIT COLDER SOLNS.  WHEN THE 06/00ZECMWF CAME IN, IT HAD LESS QPF THEN THE 06/00Z GFS SOLN WHICHSUPPORTS THIS HYPOTHESIS.  FOR NOW WILL LEAN TWD A MORE SRN TRACK.THE GENL FCST RATIONALE REMAINS THE SAME.  PRECIP WILL BE MAINLYRAIN S OF I-95 TODAY AND GENLY SNOW N OF THERE.  ITS MARCH, AND WITHTHE HIGHER SUN ANGLE, IT WILL BE TOUGH FOR IT TO ACCUMULATE MUCHDURG THE DAY ON TREATED SURFACES UNLESS IT COMES DOWN HEAVY.  ONE OFTHE KEY QUESTIONS REMAINS WHERE THE PRECIP CUT OFF WILL BE.  IF THEMORE SRN TRACK OF THE ECMWF/UKMET IS MORE CORRECT, THEN THE NRNPORTIONS OF THE REGION MAY NOT SEE MUCH AT ALL.&&.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...THE FCST BECOMES MORE PROBLEMATIC THIS EVENING.  THE PRECIP SHUDTRANSITION TO SNOW AND THEN ITS JUST A QUESTION OF HOW MUCH QPF ISLEFT.  BOTH THE EC AND GFS HAVE SOME QPF BETWEEN 07/00Z AND 07/06ZAND MUCH LESS BETWEEN 07/06Z AND 07/12Z.  SO IT REMAINS TO BE SEENHOW MUCH QPF IS LEFT AND OF COURSE, WHAT THE TEMPS ARE.SO, FOR NOW, WILL CONVERT THE WINTER STORM WATCH TO A WINTER WEATHERADVISORY FOR ALL COUNTIES WHERE IT WAS IN EFFECT AND ADD MERCER,MONMOUTH, OCEAN, SOMERSET AND HUNTED IN NJ.  DEPENDING ON WHAT LATERGUIDANCE DOES, IT THE ADVY CUD BE UPGRADED TO A WARNING FOR PORTIONSOF THE AREA.
 
 
 
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