FEFD17 Posted January 10, 2011 Share Posted January 10, 2011 18z GFS http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/18/images/nam_slp_072m.gif[/iMF 18z NAM This is the year to live in the HV What PART of the Hudson Valley is the issue...... Link to comment Share on other sites More sharing options...
Tornado Girl Posted January 10, 2011 Share Posted January 10, 2011 This storm is making for interesting forecasting. As you can see from the 18z GFS and NAM runs I posted earlier you can see that the GFS holds on to the primary for quite awhile. You can also see the NAM likes the storm a lot more then the GFS does. The NAM shows a much stronger low offshore. Timing is going to be the major key to How much snow we see. If the primary is slow to transfer energy it make the coastal weak. Like I said, The Key is going to be the timing and how fast the transfer happens. Isentropic lifting is also something this has to be watched. We could see snow earlier than we think. Link to comment Share on other sites More sharing options...
Tornado Girl Posted January 10, 2011 Share Posted January 10, 2011 What PART of the Hudson Valley is the issue...... It's too early to know for sure...but right now south of ALB Link to comment Share on other sites More sharing options...
Wx4cast Posted January 10, 2011 Author Share Posted January 10, 2011 Nice write-up from BUF on the system this week. Hopefully this holds serve and all/most of upstate NY can reach at least advisory level snow. ON TUESDAY OUR ATTENTION TURNS TO THE SYNOPTIC SCALE...WHICH HAS BEEN A RARITY SO FAR THIS WINTER. MOISTURE CHANNEL IMAGERY THIS AFTERNOON SHOWS A COMPLEX MID LEVEL CLOSED LOW CENTERED OVER THE NORTHERN ROCKIES. A SHORTWAVE ROTATING AROUND THE BASE OF THIS FEATURE WILL SPAWN SURFACE CYCLOGENESIS OVER THE SOUTHERN PLAINS ON MONDAY. 12Z MODEL GUIDANCE REMAINS IN EXCELLENT AGREEMENT WITH THE SUBSEQUENT TIMING AND AMPLITUDE OF THIS SYSTEM. THE PRIMARY SURFACELOW WILL TRACK INTO THE UPPER OHIO VALLEY TUESDAY NIGHT...WHILESECONDARY COASTAL CYCLOGENESIS OFFSHORE OF THE CAROLINAS WILL MOVE NORTH ALONG THE EASTERN SEABOARD AND ABSORB THE PRIMARY LOW BY WEDNESDAY AFTERNOON. AS THIS OCCURS...AN INVERTED TROUGH WILL HANG BACK ACROSS THE LOWER LAKES AND CONTINUE TO PROVIDE A LOW LEVEL FOCUS FOR CONTINUED LIGHT SNOW. PAST FEW MODEL RUNS HAVE TRENDED A LITTLE STRONGER WITH THE PRIMARY OHIO VALLEY LOW...AND MORE IMPORTANTLY STRONGER WITH THE ASSOCIATED MID LEVEL CLOSED LOW...WHICH IS FORECAST TO MOVE EAST ACROSS PENNSYLVANIA TUESDAY NIGHT AND WEDNESDAY WHILE STEADILY DEEPENING. FORECAST BUFKIT PROFILES SHOW A VERY DEEP LAYER OF FAVORABLE TEMPS/MOISTURE FOR DENDRITIC CRYSTAL GROWTH...ESPECIALLY ON WEDNESDAY DURING THE WRAP AROUND PHASE OF THE STORM SUGGESTING RELATIVELY HIGH SNOW/WATER RATIOS BY SYNOPTIC SNOW STANDARDS. SREF PLUME ANALYSIS FROM SELECTED POINTS ACROSS THE CWA SHOW EXCELLENT AGREEMENT AMONGST ENSEMBLE MEMBERS WITH A TIGHT CLUSTERING OF TIMING AND QPF...WITH SREF MEAN SUGGESTING QPF ON THE ORDER OF 0.30-0.40 INCHES FOR THIS EVENT FROM LATE TUESDAY AFTERNOON THROUGH WEDNESDAY. MODEL QPF IS TYPICALLY A LITTLE HIGH WITH THESE TYPES OF SYSTEMS...BUT EVEN SHAVING A LITTLE QPF OFF THE TOP SUGGESTS GOOD POTENTIAL FOR ADVISORY CRITERIA ACCUMULATIONS ACROSS MOST OF THE AREA FROM THE SOUTH SHORE OF LAKE ONTARIO TO THE PENNSYLVANIA STATE LINE. LOOKING AT THE FORECAST DETAILS...GIVEN THE EXCELLENT MODEL AGREEMENT HAVE RAISED POPS TO CATEGORICAL FOR LATER TUESDAY AFTERNOON NEAR THE PA STATE LINE...THEN EVERYWHERE EXCEPT THE SAINT LAWRENCE VALLEY FOR TUESDAY NIGHT AND WEDNESDAY. AT THIS TIME IT LOOKS LIKE A SOLID 3-5 OR 4-6 INCH TYPE EVENT FOR MOST OF THE CWA FROM THE SOUTH SHORE OF LAKE ONTARIO SOUTHWARD. WEDNESDAY NIGHT THE SYNOPTIC MOISTURE WILL BEGIN TO PULL AWAY AS THE COASTAL LOW MOVES INTO THE CANADIAN MARITIMES...BUT NORTHWEST FLOW WILL KEEP TYPICAL UPSLOPE/LAKE ENHANCED LIGHT SNOW GOING ESPECIALLY SOUTHEAST OF LAKES ERIE AND ONTARIO. I have some issues with the low upper low deepening as it moves across WNY/WPA. Synoptic climatology would tend to favor this primary weakening and transferring its energy or redeveloping itself off to the SE (lee side) of the Appalachians. With the C/O staying south of a CHI-CLE-BUF line the coastal low would tend to be far south on the coast SC/NC area probably. As I said earlier in another post. When this redevelopment towards the coast occurs the snowfall will tend to slacken considerably. While advisory snow is possible for WNY right now I am neither confident in it happening and even less confident in it being as widespread as the BUF write-up indicates. Link to comment Share on other sites More sharing options...
Wx4cast Posted January 10, 2011 Author Share Posted January 10, 2011 This storm is making for interesting forecasting. As you can see from the 18z GFS and NAM runs I posted earlier you can see that the GFS holds on to the primary for quite awhile. You can also see the NAM likes the storm a lot more then the GFS does. The NAM shows a much stronger low offshore. Timing is going to be the major key to How much snow we see. If the primary is slow to transfer energy it make the coastal weak. Like I said, The Key is going to be the timing and how fast the transfer happens. Isentropic lifting is also something this has to be watched. We could see snow earlier than we think. All good and valid points. The transfer of energy to the coastal will be key. WINGRIDDS analysis (using(2ECC macro) indicates VA Capes/Delmarva favored area for the low to start to deepen. Just based on verbatim use of GFS LP and H5 500 hPa height fall center (HFC) tracks EPA/NJ up thru lower HV and WCT (S Berkshires, too) could really get hit hard. I like your thought of Isentropic lift, too. These southern lows often have precip shileds of a few hundered miles to the north of their center's. Link to comment Share on other sites More sharing options...
gravitylover Posted January 10, 2011 Share Posted January 10, 2011 All good and valid points. The transfer of energy to the coastal will be key. WINGRIDDS analysis (using(2ECC macro) indicates VA Capes/Delmarva favored area for the low to start to deepen. Just based on verbatim use of GFS LP and H5 500 hPa height fall center (HFC) tracks EPA/NJ up thru lower HV and WCT (S Berkshires, too) could really get hit hard. I like your thought of Isentropic lift, too. These southern lows often have precip shileds of a few hundered miles to the north of their center's. Sounds like you've got me in the jackpot. I was looking at that same map and thinking hmm, a little earlier start further north due to lifting ... Whaddaya know, ~30 years of looking at weather maps and 12 or so years on these weather boards and I think I'm finally getting the hang of this stuff Thanx for verifying my thoughts. Link to comment Share on other sites More sharing options...
wolfie09 Posted January 10, 2011 Share Posted January 10, 2011 0z NAM Link to comment Share on other sites More sharing options...
snowgeek Posted January 10, 2011 Share Posted January 10, 2011 NAM FTW!!!!!!! 0z NAM Link to comment Share on other sites More sharing options...
Stash Posted January 10, 2011 Share Posted January 10, 2011 I've seen NAM over amplify or correct too many times to get sucked in too much, but will definitely get more excited if GFS and other globals follow suit. Wow, if this verified, my old stomping grounds in Western CT would get rocked a third time this winter... NAM FTW!!!!!!
Recommended Posts
Archived
This topic is now archived and is closed to further replies.