ChescoWx Posted March 24, 2013 Share Posted March 24, 2013 Latest 12z data blend of GFS and NAM for NW Chesco PA has snow beginning earlier with more by AM rush and still ends up with around 10" of snow here above 650 ft - below is the run down 9pm tonight Light Snow temp 36.4 Midnight Light Snow 34.3 3am Mod Snow temp 32.2 (0.8" accum) 6am Mod Snow temp 30.9 (1.8") 9am Heavy Snow temp 31.0 (3.0") 12noon S+ 31.4 (5.0") 3pm S+ 31.6 (7.0") 6pm S+ 31.5 (9.0") 9pm S- 31.4 (10.0") Link to comment Share on other sites More sharing options...
Fields27 Posted March 24, 2013 Share Posted March 24, 2013 It's on there Facebook site. Sorry on mobile http://www.erh.noaa.gov/phi/briefing/packages/current_briefing.pdf Thanks guys. I'm guessing the reason for no advisories/warnings in sepa is because of that 8"+ possibility if banding sets up? Although it's only 10% but it's less than 12 hours away from the start time and still nothing east of Schuylkill county. Link to comment Share on other sites More sharing options...
AbsoluteVorticity Posted March 24, 2013 Share Posted March 24, 2013 After looking at 12z obs it seems that the NAM initialized significantly better than the GFS with regard to dewpoints at kphl. Not sure if this will translate to a better handling of the thermal profile tomorrow but just something to keep in mind. Link to comment Share on other sites More sharing options...
Allsnow Posted March 24, 2013 Share Posted March 24, 2013 Euro is well se of the 00z run .5 to Phl and .25 to NYC Link to comment Share on other sites More sharing options...
Mitchell Gaines Posted March 24, 2013 Share Posted March 24, 2013 Thanks guys. I'm guessing the reason for no advisories/warnings in sepa is because of that 8"+ possibility if banding sets up? Although it's only 10% but it's less than 12 hours away from the start time and still nothing east of Schuylkill county. This afternoon's update would be the first potential oppertunity to issue advisories and/ or warnings. Link to comment Share on other sites More sharing options...
jrodd321 Posted March 24, 2013 Share Posted March 24, 2013 Mt holly up snowfall amounts a little bit on there latest briefing. Goes on to say the possibility of 8+ in cnj and snj if banding happens. Their' 8"+ circle pretty much encompasses our entire view area. Expect north towards the Poconos. Link to comment Share on other sites More sharing options...
RedSky Posted March 24, 2013 Share Posted March 24, 2013 In comes dr no with the red flag little bit drier solution I wouldn't bet against it, every once in a rare while its off some like march 16 but not often 1-3" north and west of philly Link to comment Share on other sites More sharing options...
phlwx Posted March 24, 2013 Share Posted March 24, 2013 NWS would be silly to issue a winter storm watch/warning IMO...too much going against big snow. It *could* happen but it'd be much safer to advisory in with a 1-3 for South Jersey, I-95, 2-4 NW as a CYA. Link to comment Share on other sites More sharing options...
famartin Posted March 24, 2013 Share Posted March 24, 2013 I think I'll call it 1-4" for TTN. I'm nervous it could be more if the GFS/NAM camp is right, or less if the EC/GEM camp is. Pain in the butt forecast. Link to comment Share on other sites More sharing options...
cast4 Posted March 24, 2013 Share Posted March 24, 2013 NWS would be silly to issue a winter storm watch/warning IMO...too much going against big snow. It *could* happen but it'd be much safer to advisory in with a 1-3 for South Jersey, I-95, 2-4 NW as a CYA. nice call. Yeah, there's big bust potential with a warning here. Link to comment Share on other sites More sharing options...
RobbTC Posted March 24, 2013 Share Posted March 24, 2013 330 PM EDT SUN MAR 24 2013 ...WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 6 PM EDT MONDAY... .TONIGHT...CLOUDY. A CHANCE OF RAIN THIS EVENING...THEN SNOW WITH RAIN LIKELY AFTER MIDNIGHT. LITTLE OR NO SNOW ACCUMULATION. LOWS IN THE MID 30S. SOUTHEAST WINDS AROUND 5 MPH...BECOMING NORTHEAST AFTER MIDNIGHT. CHANCE OF PRECIPITATION 80 PERCENT..MONDAY...SNOW. RAIN IN THE AFTERNOON. SNOW ACCUMULATION OF 2 TO 4 INCHES. HIGHS IN THE MID 30S. NORTHEAST WINDS 10 TO 15 MPH WITH GUSTS UP TO 25 MPH. CHANCE OF PRECIPITATION NEAR 100 PERCENT..MONDAY NIGHT...CLOUDY. SNOW AND RAIN LIKELY IN THE EVENING. LITTLE OR NO ADDITIONAL SNOW ACCUMULATION. LOWS AROUND 30. NORTHWEST WINDS 10 TO 15 MPH. CHANCE OF PRECIPITATION 70 PERCENT. Link to comment Share on other sites More sharing options...
phlwx Posted March 24, 2013 Share Posted March 24, 2013 WSW South Jersey, WWA's for everyone else. Link to comment Share on other sites More sharing options...
RobbTC Posted March 24, 2013 Share Posted March 24, 2013 WSW South Jersey, WWA's for everyone else. Accuweather got a win? wow. ;-) Link to comment Share on other sites More sharing options...
RowanBrandon Posted March 24, 2013 Share Posted March 24, 2013 The only model that really shows totals near that is the NAM, so it's interesting. Link to comment Share on other sites More sharing options...
famartin Posted March 24, 2013 Share Posted March 24, 2013 WSW South Jersey, WWA's for everyone else. WWA: PA Berks, Chester, Montgomery, Bucks, Philadelphia, Delaware; NJ Morris, Hunterdon, Somerset, Middlesex, Mercer, Monmouth, Cape May; DE New Castle, Kent, Sussex WSW: NJ Ocean, Burlington, Camden, Gloucester, Salem, Atlantic Accums are generally 2-4 in the advisory area (except S DE) and 3-5 in the warning. Link to comment Share on other sites More sharing options...
Mitchell Gaines Posted March 24, 2013 Share Posted March 24, 2013 WSW South Jersey, WWA's for everyone else. Yes we went warning in South NJ. 3-5 in the warning area, general 1-4 around it, more mixing south and less precip north. Link to comment Share on other sites More sharing options...
Mitchell Gaines Posted March 24, 2013 Share Posted March 24, 2013 The only model that really shows totals near that is the NAM, so it's interesting. GFS isn't far off the forecast. Link to comment Share on other sites More sharing options...
Allsnow Posted March 24, 2013 Share Posted March 24, 2013 Walt drag had a interesting afd. Goes on to say how inside 5 days the gfs and srefs have done better then the euro around phl Link to comment Share on other sites More sharing options...
Allsnow Posted March 24, 2013 Share Posted March 24, 2013 The only model that really shows totals near that is the NAM, so it's interesting. Gfs has the same amount of preciep and dynamics, just 2m temps are warmer. Link to comment Share on other sites More sharing options...
phlwx Posted March 24, 2013 Share Posted March 24, 2013 Walt drag had a interesting afd. Goes on to say how inside 5 days the gfs and srefs have done better then the euro around phl and he wrote that before 3/5 when the SREFs were shoving 6" into Philly for Snoquester. We all saw how well that went. (I like Walt but to be fair, that GFS/SREF comment seemed a bit unfounded especially since the Euro's QPF outperformed the other modeling with Snoquester). Link to comment Share on other sites More sharing options...
RowanBrandon Posted March 24, 2013 Share Posted March 24, 2013 Gfs has the same amount of preciep and dynamics, just 2m temps are warmer. That is my concern. The 2m temps killed the snowquester storm. Link to comment Share on other sites More sharing options...
famartin Posted March 24, 2013 Share Posted March 24, 2013 and he wrote that before 3/5 when the SREFs were shoving 6" into Philly. We all saw how well that went. I was wondering where this AFD was. I don't think the SREFs did all that great with 2/8 either, did they? I recall an AFD around the similar time as this purported Drag one where he mentioned Tony cautioned him about the SREFs being too wet on a regular basis. Link to comment Share on other sites More sharing options...
Allsnow Posted March 24, 2013 Share Posted March 24, 2013 and he wrote that before 3/5 when the SREFs were shoving 6" into Philly for Snoquester. We all saw how well that went. (I like Walt but to be fair, that GFS/SREF comment seemed a bit unfounded especially since the Euro's QPF outperformed the other modeling with Snoquester). The gfs did the best that event for Phl correct? It will be interesting to see what happens. Link to comment Share on other sites More sharing options...
Allsnow Posted March 24, 2013 Share Posted March 24, 2013 Nam not backing down at 18z lol. Link to comment Share on other sites More sharing options...
famartin Posted March 24, 2013 Share Posted March 24, 2013 The gfs did the best that event for Phl correct? It will be interesting to see what happens. EC or GFS, they were both very close. Unlike with this event. Link to comment Share on other sites More sharing options...
phlwx Posted March 24, 2013 Share Posted March 24, 2013 The gfs did the best that event for Phl correct? It will be interesting to see what happens. Barely...Euro had .59, GFS had .50. Reality was .13. Not a huge difference. Euro was colder than GFS though. Link to comment Share on other sites More sharing options...
RowanBrandon Posted March 24, 2013 Share Posted March 24, 2013 Nam not backing down at 18z lol. Precip shield is shifted east and shrunk a bit. Link to comment Share on other sites More sharing options...
Allsnow Posted March 24, 2013 Share Posted March 24, 2013 Thanks guys. Looks like the nam just shifted a bit s/e of its previous run. Link to comment Share on other sites More sharing options...
phlwx Posted March 24, 2013 Share Posted March 24, 2013 PHI going with evaporative cooling and hoping they're right in their AFD: NEAR TERM /UNTIL 6 AM MONDAY MORNING/ WELL IT WAS TIME TO MAKE A DECISION AND TO BE QUITE HONEST CANT SAY THAT THIS IS A CONFIDENT ONE WHICH IS PRETTY MUCH THE WAY SNOW FORECASTS HAVE GONE FOR MOST OF THIS WINTER. PLEASE STAY TUNED FOR LIKELY UPDATES AND CHANGES TO AMOUNTS AND OR HEADLINES AS THIS REMAINS A DIFFICULT FORECAST TO PEG. THE MODELS ARE ALL VERY SIMILAR IN RAPIDLY DEVELOPING A LOW PRESSURE SYSTEM OFF OF THE VIRGINIA COAST WHICH WILL CAUSE AN INITIAL PRECIPITATION BURST DURING THE MORNING. THE DIFFERENCES COME WITH THE SECONDARY SURGE DURING THE AFTERNOON AS THE TROWAL DEVELOPS. THE NON-US MODELS ARE FARTHER OFFSHORE AND SUPPORT LIGHTER QPF AMOUNTS WHILE THE DOMESTIC MODELS WOULD HIT SOUTHEASTERN/EASTERN NJ PRETTY HARD. THIS IS ALMOST A FLIP IN THE FORECAST WE HAD GOING WITH THE BULK OF THE HEAVIER SNOW NORTH AND WEST OF THE FALL LINE. WE HOPE OUR FLIP IS CORRECT AS WE HAVE INCREASED SNOW AMOUNTS SE OF I95 WHILE KEEPING GENERALLY KEEPING SIMILAR AMOUNTS NORTH AND WEST. THE PREDECESSOR AIR MASS IS CONSIDERABLY DRIER THAN THE ONE IN EARLY MARCH THAT GAVE US FCSTING FITS AND WHILE THE PAPARAZZI CHASES DYNAMIC COOLING AROUND, EVAPORATIONAL COOLING WHICH ONLY HAS SOME PERSON WITH A POLAROID WATCHING IT IS ACTUALLY A MORE EFFECTIVE SNOW PRODUCER. SO FOR TONIGHT WHEN PRECIPITATION INITIALLY STARTS, BOUNDARY TEMPERATURES SHOULD SUPPORT A START AS RAIN AND THEN THE PTYPE SHOULD TRANSITION TO SNOW AS EVAPORATIONAL COOLING TAKES HOLD. WHILE THE NAM/WRF-NMMB HAS A COLD BIAS ITS MOS GUIDANCE IS LIKELY CLOSER TO THE CORRECT TEMPERATURE SCENARIO AGAIN AND WAS FOLLOWED CLOSER. SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/ TOMORROW COMES DOWN AS TO WHETHER PRECIPITATION INTENSITY CAN OUTDUEL THE LATE MARCH SUN ANGLE AND POSSIBLY SOME MARGINAL BOUNDARY LAYER CONDITIONS. CONFIDENCE IN SNOW AMOUNTS DECREASE DURING THE SECOND HALF OF THE DAY (NOT THAT THEY ARE HIGH IN THE FIRST HALF) AS THIS IS WHEN THE CONFLICT WILL BE PEAKING. IN THE FIRST HALF OF THE DAY, WE HAVE SEEN THE RECENT WRAP AROUND SNOWS ACCUMULATE RATHER EASILY AND EVEN SAW THE 1 INCH SNOWS DO WELL AROUND NOON ALONG THE IMMEDIATE COAST LAST WEEK. SO EVAP COOLING MOST PLACES TO SNOW, WE WOULD ENVISION SOME ROADWAY PROBLEMS FROM RDG TO THE PHL METRO AREA SOUTHWEST FOR THE MORNING COMMUTE. ONCE WE REACH THE FALL LINE IT WILL BE DIFFICULT FOR THE PTYPE TO NOT BE SNOW. AS WE GO LATER IN THE MORNING THE RAPID DEEPENING BY LOGIC WOULD SUPPORT AN EXPANDING OF THE PCPN SHIELD AS WELL AS INCREASE IN PCPN INTENSITY. THIS RIGHT NOW EVEN IN SOME OF THE NON US MODEL SOLUTIONS HAS SOUTHEASTERN NJ UNDER THE MOST FAVORABLE LOCATION FOR DYNAMICALLY COOLED SNOW OR ACCUMULATING SNOW BECAUSE OF THE GENERAL INTENSITY. THE DIFFERENCE COMES IN THE AFTERNOON WHETHER OR NOT ACCUMULATING SNOW CAN BE ONGOING AS WE WILL NEED THE INTENSITY AS DISPLAYED IN THE U.S. MODELS FOR THIS TO CONTINUE. NORTH AND WEST OF THE FALL LINE WE TOOK ABOUT 2/3RDS OF THE NAMS QPF AND APPLIED CLOSE TO A 10:1 RATIO FOR SNOWFALL. ELSEWHERE WE TOOK SIMILAR AMOUNTS OFF, BUT APPLIED A RATIO BETWEEN 5:1 TO 8:1 TO ARRIVE AT OUR SNOWFALL TOTALS. ONCE PRECIPITATION STARTS TO LESSEN DURING THE AFTERNOON, A MIX OR CHANGE TO RAIN COULD OCCUR. OBVIOUSLY THE SNOW WILL HAVE AN EASIER TIME OF ACCUMULATING ON NON PAVED SURFACES AND DONT KNOW IF WE WILL REACH THE POINT WHERE SNOW WILL BE A PROBLEM ON TREES AND TREE LIMBS. WE DO CATCH A BREAK THAT NOTHING IS EVEN STARTING TO BLOOM. OTHER SENSIBLE WEATHER, THE SLIGHT EASTWARD JOG OF THE 12Z NAM KEEPS THE STRONGEST WIND FIELDS OFFSHORE. THE GFS ALSO CONCURS AS DOES OUR WIND CHECKLIST. CONFIDENCE IS NOW TOO LOW TO ISSUE A WIND ADVISORY FOR THE COASTAL ZONES. AS FAR AS TEMPERATURES GO, THEY ARE MUCH CLOSER TO NAM MOS THAN GFS MOS. Link to comment Share on other sites More sharing options...
famartin Posted March 24, 2013 Share Posted March 24, 2013 New NAM just about cut QPF in half back home. Link to comment Share on other sites More sharing options...
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