TUweathermanDD Posted October 28, 2012 Share Posted October 28, 2012 IN ADDITION...HURRICANE-FORCE WINDS ARE EXPECTED ALONG PORTIONS OF THE COAST BETWEEN CHINCOTEAGUE VIRGINIA AND CHATHAM MASSACHUSETTS. THIS INCLUDES THE TIDAL POTOMAC FROM COBB ISLAND TO SMITH POINT... THE MIDDLE AND UPPER CHESAPEAKE BAY...DELAWARE BAY...AND THE COASTS OF THE NORTHERN DELMARVA PENINSULA...NEW JERSEY...THE NEW YORK CITY AREA...LONG ISLAND...CONNECTICUT...AND RHODE ISLAND. I live 5 miles from the Bay, and my girl lives on the water, we're gonna the best gusts, 70-80mph Link to comment Share on other sites More sharing options...
KAOS Posted October 28, 2012 Share Posted October 28, 2012 Link to comment Share on other sites More sharing options...
yoda Posted October 28, 2012 Share Posted October 28, 2012 NHC now showing TROPICAL cyclone landfall in S NJ Link to comment Share on other sites More sharing options...
KAOS Posted October 28, 2012 Share Posted October 28, 2012 Cone has shrunk. Also now a tropical cyclone at landfall again. Link to comment Share on other sites More sharing options...
nj2va Posted October 28, 2012 Share Posted October 28, 2012 So sometime within the next few hours, we should start to see her turn NNE, N, then eventually NNW tomorrow morning, judging by models/NHC guidance? Link to comment Share on other sites More sharing options...
Wonderdog Posted October 28, 2012 Share Posted October 28, 2012 So sometime within the next few hours, we should start to see her turn NNE, N, then eventually NNW tomorrow morning, judging by models/NHC guidance? Yes. Link to comment Share on other sites More sharing options...
yoda Posted October 28, 2012 Share Posted October 28, 2012 A BUOY NEAR THE MOUTH OF THE CHESAPEAKE BAY RECENTLY REPORTED SUSTAINED WINDS OF 50 MPH... 83 KM/H...WITH A GUST TO 59 MPH...94 KM/H Link to comment Share on other sites More sharing options...
PhineasC Posted October 28, 2012 Share Posted October 28, 2012 NHC now showing TROPICAL cyclone landfall in S NJ South too. Looks close to the Delaware Bay. Link to comment Share on other sites More sharing options...
KAOS Posted October 28, 2012 Share Posted October 28, 2012 Pressure up to 952....some are saying it is up 1 mb....but I believe it was actually 951.9 before. So technically up a tenth. Splitting hairs...I guess. Link to comment Share on other sites More sharing options...
EasternUSWX Posted October 28, 2012 Share Posted October 28, 2012 NHC now showing TROPICAL cyclone landfall in S NJ They keep doing that, fixed again. Link to comment Share on other sites More sharing options...
Snowpocalypse Posted October 28, 2012 Share Posted October 28, 2012 I'm in cecil county and from what I've read on here a lower nj lf would be better for my area because the lull in the winds near the center, is that correct? Or have I misinterpreted it? Link to comment Share on other sites More sharing options...
EasternUSWX Posted October 28, 2012 Share Posted October 28, 2012 Interesting NHC keep it moving up over central PA while NAM/GFS stall it over SW PA. Link to comment Share on other sites More sharing options...
WVclimo Posted October 28, 2012 Share Posted October 28, 2012 This product from NWS has DC with peak gusts at 63 mph, Baltimore at 80 mph. http://www.srh.noaa.gov/data/LWX/AFMLWX Link to comment Share on other sites More sharing options...
yoda Posted October 28, 2012 Share Posted October 28, 2012 This is the lower half of the Tidal Potomac FYI... upper half still Storm Warning URGENT - MARINE WEATHER MESSAGE NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 501 PM EDT SUN OCT 28 2012 ANZ537-290515- /O.UPG.KLWX.SR.W.0001.000000T0000Z-121031T0000Z/ /O.EXA.KLWX.HF.W.0001.000000T0000Z-121031T0000Z/ TIDAL POTOMAC FROM COBB ISLAND MD TO SMITH POINT VA- 501 PM EDT SUN OCT 28 2012 ...HURRICANE FORCE WIND WARNING IN EFFECT UNTIL 8 PM EDT TUESDAY... THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A HURRICANE FORCE WIND WARNING...WHICH IS IN EFFECT UNTIL 8 PM EDT TUESDAY. THE STORM WARNING IS NO LONGER IN EFFECT. * WINDS...64 KNOTS OR GREATER WITHIN THE HURRICANE FORCE WIND WARNING. 48 TO 63 KNOTS WITHIN THE STORM WARNING. Link to comment Share on other sites More sharing options...
mattie g Posted October 28, 2012 Share Posted October 28, 2012 I'm just glad that heavy stuff stayed east of the bay today. The less rain during this whole event, the better. Link to comment Share on other sites More sharing options...
yoda Posted October 28, 2012 Share Posted October 28, 2012 LWX again ramping up... though 60-70 arent hurricane force... URGENT - WEATHER MESSAGE NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 501 PM EDT SUN OCT 28 2012 ...THE NATIONAL HURRICANE CENTER FORECASTS HURRICANE SANDY TO TRACK TO THE NORTHEAST TO A POSITION WELL OFF THE NORTH CAROLINA COAST TONIGHT...BEFORE SHIFTING TO THE NORTHWEST AND MOVING TOWARD NEW JERSEY MONDAY INTO TUESDAY. THE TRACK OF SANDY IS EXPECTED TO BRING HIGH WINDS TO THE REGION MONDAY MORNING THROUGH TUESDAY EVENING... DCZ001-MDZ004>007-009>011-013-014-016>018-VAZ053-054-290515- /O.CON.KLWX.HW.W.0002.121029T1200Z-121031T0000Z/ DISTRICT OF COLUMBIA-FREDERICK MD-CARROLL-NORTHERN BALTIMORE- HARFORD-MONTGOMERY-HOWARD-SOUTHERN BALTIMORE-PRINCE GEORGES- ANNE ARUNDEL-CHARLES-ST. MARYS-CALVERT-FAIRFAX- ARLINGTON/FALLS CHURCH/ALEXANDRIA- INCLUDING THE CITIES OF...WASHINGTON...FREDERICK...WESTMINSTER... GAITHERSBURG...COLUMBIA...BALTIMORE...ANNAPOLIS...WALDORF... ST MARYS CITY...FAIRFAX...ALEXANDRIA...FALLS CHURCH 501 PM EDT SUN OCT 28 2012 ...HIGH WIND WARNING REMAINS IN EFFECT FROM 8 AM MONDAY TO 8 PM EDT TUESDAY... * TIMING...SUSTAINED WINDS OF 30 TO 40 MPH ARE EXPECTED BY 8 AM MONDAY...THEN INCREASING AROUND NOONTIME MONDAY TO 35 TO 45 MPH WITH HURRICANE FORCE WIND GUSTS 60 TO 70 MPH LASTING INTO EARLY TUESDAY MORNING. * IMPACTS...A PROLONGED AND SIGNIFICANT 24 HOUR HIGH WIND EVENT WILL TAKE PLACE ACROSS THE WARNING AREA. COUPLED WITH HEAVY RAINS FROM SANDY...THE HIGH WINDS WILL LEAD TO SIGNIFICANT TREE DAMAGE. RESIDENTS...VISITORS... AND BUSINESSES ACROSS THE REGION SHOULD PLAN FOR WIDESPREAD POWER AND COMMUNICATION OUTAGES. Link to comment Share on other sites More sharing options...
yoda Posted October 28, 2012 Share Posted October 28, 2012 Prince William/Loudoun/Stafford/King George also included in that above (slightly different warning) Link to comment Share on other sites More sharing options...
MN Transplant Posted October 28, 2012 Share Posted October 28, 2012 60mph gusts as early as 9am per LWX. Link to comment Share on other sites More sharing options...
Ian Posted October 28, 2012 Share Posted October 28, 2012 * TIMING...SUSTAINED WINDS OF 30 TO 40 MPH ARE EXPECTED BY 8 AM MONDAY...THEN INCREASING AROUND NOONTIME MONDAY TO 35 TO 45 MPH WITH HURRICANE FORCE WIND GUSTS 60 TO 70 MPH LASTING INTO EARLY TUESDAY MORNING. yeah they were conservative early probably in case it shifted as there is a fairly steep gradient from the strongest to just strong to our sw. Link to comment Share on other sites More sharing options...
Bob Chill Posted October 28, 2012 Share Posted October 28, 2012 Can someone explain model SLP initialization? 18z nam shows 968 @ init. 12z gfs showed 972. Why is this? I'm sure there is a reason but pressures just seem way off. 18z nam shows 960'ish at landfall. Wouldn't we expect 950'ish at this point? Even mid 940's seem more likely than 960. Link to comment Share on other sites More sharing options...
Ian Posted October 28, 2012 Share Posted October 28, 2012 Can someone explain model SLP initialization? 18z nam shows 968 @ init. 12z gfs showed 972. Why is this? I'm sure there is a reason but pressures just seem way off. 18z nam shows 960'ish at landfall. Wouldn't we expect 950'ish at this point? Even mid 940's seem more likely than 960. I can't explain it but I know deep tropical systems are almost always initialized too weak. Link to comment Share on other sites More sharing options...
MillzPirate Posted October 28, 2012 Share Posted October 28, 2012 18z NAM pretty close to snow at IAD Link to comment Share on other sites More sharing options...
left_gulley Posted October 28, 2012 Share Posted October 28, 2012 Can someone explain model SLP initialization? 18z nam shows 968 @ init. 12z gfs showed 972. Why is this? I'm sure there is a reason but pressures just seem way off. 18z nam shows 960'ish at landfall. Wouldn't we expect 950'ish at this point? Even mid 940's seem more likely than 960. See posts 262 and 265: http://www.americanwx.com/bb/index.php/topic/37397-hurricane-sandy-model-and-medium-range-discussion/page__st__245 Link to comment Share on other sites More sharing options...
mattie g Posted October 28, 2012 Share Posted October 28, 2012 Can someone explain model SLP initialization? 18z nam shows 968 @ init. 12z gfs showed 972. Why is this? I'm sure there is a reason but pressures just seem way off. 18z nam shows 960'ish at landfall. Wouldn't we expect 950'ish at this point? Even mid 940's seem more likely than 960. I just read a post by dtk in the general forum that explained it. Link to comment Share on other sites More sharing options...
dtk Posted October 28, 2012 Share Posted October 28, 2012 Can someone explain model SLP initialization? 18z nam shows 968 @ init. 12z gfs showed 972. Why is this? I'm sure there is a reason but pressures just seem way off. 18z nam shows 960'ish at landfall. Wouldn't we expect 950'ish at this point? Even mid 940's seem more likely than 960. I have a follow up to a post that Phil made in the main tropical modeling thread. It basically has to do with representativeness (i.e. they are intentionally given initial conditions that do not result in significant spin-down issues).... The NAM uses very little data in the vicinity of TCs (no bogusing, no relocation, etc.). The GFS does draw toward the NHC issues advisory SLP, but conservatively so (I have a paper on this if people are interested). There is also an issue of post processing (the SLP field that is plotted is not actually from the model...it is interpoloated and smoothed, at least for the GFS). I am hoping that we can convince people to start using the non-smoothed (alternative extrapolation) version of SLP (which already exists in our grib files) for the GFS. Link to comment Share on other sites More sharing options...
usedtobe Posted October 28, 2012 Author Share Posted October 28, 2012 I have a follow up to a post that Phil made in the main tropical modeling thread. It basically has to do with representativeness (i.e. they are intentionally given initial conditions that do not result in significant spin-down issues).... The NAM uses very little data in the vicinity of TCs (no bogusing, no relocation, etc.). The GFS does draw toward the NHC issues advisory SLP, but conservatively so (I have a paper on this if people are interested). There is also an issue of post processing (the SLP field that is plotted is not actually from the model...it is interpoloated and smoothed, at least for the GFS). I am hoping that we can convince people to start using the non-smoothed (alternative extrapolation) version of SLP (which already exists in our grib files) for the GFS. I'm glad you answered, I started to but you know more about the subject than I do. Link to comment Share on other sites More sharing options...
dtk Posted October 28, 2012 Share Posted October 28, 2012 I'm glad you answered, I started to but you know more about the subject than I do. Wes, your comment about smoothing is also a good one. The estimated minimum SLP from NHC is a point measurement, not something we can simply drop into the model. The net effect of the assimilation is to take that information and smooth it out (typicall with reduced amplitude). Furthermore, observations have errors too, so we cannot statistically assume that the observation is ground truth (hence it is combined with the model state through the assimilation process). People really need to be careful NOT to use the initialized minimum SLP for a reason as to whether or not to use model A over model B. The hurricane models (HWRF, GFDL) generally use various initialization and or bogusing techniques to attempt to put in vortices as close to the observations as possible (but again, those model's inner domains are explicitly designed to forecasts TCs). Link to comment Share on other sites More sharing options...
Bob Chill Posted October 28, 2012 Share Posted October 28, 2012 Thanks all for the excellent explanations. Does the same pressure differences in the solutions change anything irt sensible wx at the surface? Doesn't look like it to me but I'm far from an expert on this stuff. Edit: I want to add one more question that seems important. If the GFS / NAM show the pressure dropping 10+/- mb between init and lf, can we assume the same 10mb drop from where we are now? A 940mb LF is quite concerning but I'm not sure expecting something like that is realistic. Link to comment Share on other sites More sharing options...
clskinsfan Posted October 28, 2012 Share Posted October 28, 2012 It looks pretty darn good this afternoon.. inner core has rebuilt a good bit. I wonder what happens if it doesn't ET transition fully. I won't join on the NHC bashing but it is weird to have "the biggest storm ever" and no warnings from them north of NC. Will we be able to call it the great hurricane of 2012? That picture is simply amazing. Absolutely huge storm. Has anyone ever seen a hurricane hit the N/E with that kind of size? Link to comment Share on other sites More sharing options...
usedtobe Posted October 28, 2012 Author Share Posted October 28, 2012 Wes, your comment about smoothing is also a good one. The estimated minimum SLP from NHC is a point measurement, not something we can simply drop into the model. The net effect of the assimilation is to take that information and smooth it out (typicall with reduced amplitude). Furthermore, observations have errors too, so we cannot statistically assume that the observation is ground truth (hence it is combined with the model state through the assimilation process). People really need to be careful NOT to use the initialized minimum SLP for a reason as to whether or not to use model A over model B. The hurricane models (HWRF, GFDL) generally use various initialization and or bogusing techniques to attempt to put in vortices as close to the observations as possible (but again, those model's inner domains are explicitly designed to forecasts TCs). Daryl, I deleted my post after you made yours but I agree that people need to be real careful about blowing off a solution based on having too weak a surface low. Link to comment Share on other sites More sharing options...
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