PhineasC Posted October 28, 2012 Share Posted October 28, 2012 The GGEM and UKMET now basically agree with the GFS and Euro. We appear to have consensus. Link to comment Share on other sites More sharing options...
EasternUSWX Posted October 28, 2012 Share Posted October 28, 2012 Re: converting 900 mb winds to surface... I talked to Wes about this earlier and he said - back of the envelope - reduce them by 20 percent (that's assuming little/no instability to mix them down)... When you do the math, the numbers are still ominous! Jason I thought you reduce 850mb winds 20% Would think 900mb would be like 15%. And ya still it's going to be hella windy. Link to comment Share on other sites More sharing options...
Disc Posted October 28, 2012 Share Posted October 28, 2012 850mb winds to the surface you reduce by 75 to 80 percent, correct? Link to comment Share on other sites More sharing options...
yoda Posted October 28, 2012 Share Posted October 28, 2012 Re: converting 900 mb winds to surface... I talked to Wes about this earlier and he said - back of the envelope - reduce them by 20 percent (that's assuming little/no instability to mix them down)... When you do the math, the numbers are still ominous! Jason So lets say the map above Ian posted was 80 kts. I multiply *.8 and get 64 kts. Thats ~75 mph Link to comment Share on other sites More sharing options...
CoastalWx Posted October 28, 2012 Share Posted October 28, 2012 Those soundings did show a very slow temp decrease with height..IOW, it will take some sort of heavy precip drag I think to mix down a lot of it..but it's possible in those areas that get heavy rain. Link to comment Share on other sites More sharing options...
chris87 Posted October 28, 2012 Share Posted October 28, 2012 Those soundings did show a very slow temp decrease with height..IOW, it will take some sort of heavy precip drag I think to mix down a lot of it..but it's possible in those areas that get heavy rain. exactly, those % extrapolations to the surface might be valid in a tropical-like sounding (like you see north of the center) but south of the center, the inversion is strong...we'll see strong gusts mixed down with any convective elements in the rainbands...but i'd take a step back on the expectations of assuming only a 15% or 20% reduction of 900 mb winds... Link to comment Share on other sites More sharing options...
CoastalWx Posted October 28, 2012 Share Posted October 28, 2012 exactly, those % extrapolations to the surface might be valid in a tropical-like sounding (like you see north of the center) but south of the center, the inversion is strong...we'll see strong gusts mixed down with any convective elements in the rainbands...but i'd take a step back on the expectations of assuming only a 15% or 20% reduction of 900 mb winds... It may be tricky though because heavier elements of rain may bring it down. Tough to really say. Even up here there is some inversion with strong WAA aloft too. Link to comment Share on other sites More sharing options...
chris87 Posted October 28, 2012 Share Posted October 28, 2012 It may be tricky though because heavier elements of rain may bring it down. Tough to really say. Even up here there is some inversion with strong WAA aloft too. oh i agree, i'm worried about some strong gusts...just think north of the center will be much more efficient at mixing down Link to comment Share on other sites More sharing options...
Ellinwood Posted October 28, 2012 Share Posted October 28, 2012 I hope this gets fixed soon... 03:35Z KLWX just encountered a hardware failure and is down. a tech is en route to evaluate. Link to comment Share on other sites More sharing options...
Ian Posted October 28, 2012 Share Posted October 28, 2012 It may be tricky though because heavier elements of rain may bring it down. Tough to really say. Even up here there is some inversion with strong WAA aloft too. Seems like the overall setup might be for light to moderate damage over most of the area with a maximized zone of perhaps considerably more problems coinciding with the heavier precip axis. This could in theory probably impact the whole DC/Balt zone. Link to comment Share on other sites More sharing options...
CoastalWx Posted October 28, 2012 Share Posted October 28, 2012 Seems like the overall setup might be for light to moderate damage over most of the area with a maximized zone of perhaps considerably more problems coinciding with the heavier precip axis. This could in theory probably impact the whole DC/Balt zone. Yeah I would agree. It's so weird to have heavy rain on screaming winds off the mountains, but when you have mid level processes generate precip like deformation zones...and strong low level convergence too I might add...I think the downslope factor does not really matter much. Link to comment Share on other sites More sharing options...
EasternUSWX Posted October 28, 2012 Share Posted October 28, 2012 Conditions begin to go downhill today Good evening everyone, an historic storm is in the making as Hurricane Sandy will combine energy with a upper level trough coming across the Ohio Valley. This storm will have wide reaching effects from the Carolinas to the Northeast, back into the Ohio Valley. Model runs have come in tonight and it looks like the most likely landfall for Sandy will be somewhere between Southern and Central New Jersey. After landfall Sandy will move almost due west or a bit south of due west. The image above (click it to make it larger) is the latest 0Z GFS model, it is showing a strong system of around 952MB over Southeastern Pennsylvania. This storm will spread its winds out over a very large area. Tropical storm force winds extend over 400 miles outward. We'll will now discuss what the effects will be from this large and dangerous storm system. The first issue will be that of heavy rains. Rain will begin lightly tomorrow afternoon as the front and some energy sparks light rain but, the heaviest rain moves in Monday afternoon. Rainfall will exceed 4 inches in many areas with some amounts as high as 10 inches possible. Even decent heavy rains will spread all the way back into Ohio and up into Maine. The National Weather Service offices have issued a Flood Watches for Northern Virginia, Maryland, Pennsylvania, Eastern Ohio, Delaware, New Jersey, New York, Connecticut, Rode Island and parts of Vermont, New Hampshire and Massachusetts. Along with the heavy rains will be the coastal and bay flooding from a high tide and a full moon while this system hits the region. Tides may rise as high as 8 feet along the coast of New Jersey and Long Island. The Chesapeake Bay and Delaware Bay will also see significant rises. Winds will be the next major issue. The big problem is not just the speed of the winds themselves but, how long they will be lasting and combined with the heavy rain it will cause trees to fall easier. Winds along the coast may gust as high as 80 or 90 miles per hour at the peak of the storm, while a good deal of the area will be gusting up to or over 60 miles per hour. The winds will last 24 to 36 hours with sustained winds over 40 miles per hour at times it will cause significant tree damage and cause likely power outages for most of the region. The National Weather Service offices have issued various High Wind Watches for this reason. The strongest of the winds start Monday afternoon and last through Tuesday afternoon. Not like rain and wind are the only problems. Parts of the region, West Virginia mainly, will pick up over a foot of snow from this event. Cold air will wrap around the low pressure system as it moves over Pennsylvania and transfer down enough could air to dump gobs and gobs of snow on the Mountains of West Virginia. Tuesday will be very chilly in Pennsylvania, Maryland, West Virginia and Virginia with temperatures dropping into the 30's and 40's. It will actually be warmer in New England with temperatures in the 60's. As the cold air continues to filter in it isn't impossible for some flakes to fall even over South Central Pennsylvania and Northwest Maryland. TIMELINE OF IMPACT Sunday: Light rain begins late in the morning/early afternoon (in earnest), with winds just beginning to pick up out of the north 15 to 20 mph with higher gusts to 30mph. On Sunday Night, rain becomes heavy and persist into the overnight with Tropical Storm conditions developing, winds gusting 35 to 45 mph. Monday: The worst day of our forecast, with Tropical Storm Conditions in the Baltimore metro all day, winds sustained 25-35 mph with gusts to 55 mph in the afternoon. This will be accompanied by torrential rains in squalls that extend into the evening, and will mix down strong winds in the evening with very strong winds at 925mb to produce winds sustained up to 50mph Monday Night with some gusts in the overnight approaching 75-80 mph. Tuesday: Heavy rains and squalls continue into Tuesday, as the center of the storm begins to pass through Central Pennsylvania, with winds gusting to hurricane force in the morning, with on and off squally weather persisting into the afternoon. Colder temperatures will wrap into the system, producing snowfall in the western areas just east of the heavy snow (which will approach 2 feet in some places), the cold air will assist in a changeover. Conditions begin to improve Tuesday evening in Maryland through the Northeast, with moderate showers still being isolated, with some snow showers in places west of interstate 95. You still have some time early tomorrow morning to prepare for this large and likely historic storm system. Please take the situation seriously. I am hearing some people just believe we are getting a little rain. Those people are in for a rude awakening. Stay tuned here for the latest. Brisko/Krimm Link to comment Share on other sites More sharing options...
Ian Posted October 28, 2012 Share Posted October 28, 2012 Yeah I would agree. It's so weird to have heavy rain on screaming winds off the mountains, but when you have mid level processes generate precip like deformation zones...and strong low level convergence too I might add...I think the downslope factor does not really matter much. The whole thing is weird. For some reason I keep thinking back to the wintertime wind events we had (I think) two winters ago--caused some windblown fires in the area but was in dead of stick tree time. Partly because those are about the longest duration events beside Irene I've seen here. DC is still pretty green. I know it drops quick NW or at least leaves are fragile etc. Link to comment Share on other sites More sharing options...
yoda Posted October 28, 2012 Share Posted October 28, 2012 I hope this gets fixed soon... Just encountered? This is a bad time to suffer hardware failure... Link to comment Share on other sites More sharing options...
PhineasC Posted October 28, 2012 Share Posted October 28, 2012 Sounds like the Euro is a little south of 12Z but very similar to the other global models. Link to comment Share on other sites More sharing options...
Nikolai Posted October 28, 2012 Share Posted October 28, 2012 wennie snow maps Link to comment Share on other sites More sharing options...
Ellinwood Posted October 28, 2012 Share Posted October 28, 2012 Sounds like the Euro is a little south of 12Z but very similar to the other global models. 00z Euro Op is at exactly the same position as the 12z at landfall... central NJ. EDIT: After Sandy moves inland, it does come a bit further south into north-central MD versus south-central PA. No notable difference in the 850mb temps except just a tad warmer over southern VA. Link to comment Share on other sites More sharing options...
Deck Pic Posted October 28, 2012 Share Posted October 28, 2012 Sounds like the Euro is a little south of 12Z but very similar to the other global models. the euro is about as much impact as we can get without a delmarva landfall....a beast Link to comment Share on other sites More sharing options...
EasternUSWX Posted October 28, 2012 Share Posted October 28, 2012 Latest CTP update has Lancaster County gusting to 75mph. Wonder if LWX will go up. Link to comment Share on other sites More sharing options...
Jebman Posted October 28, 2012 Share Posted October 28, 2012 Light to moderate rain in Dale City. 56 degrees with NE winds 10 mph gusting to 16 Link to comment Share on other sites More sharing options...
Jebman Posted October 28, 2012 Share Posted October 28, 2012 000 FXUS61 KLWX 280827 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 427 AM EDT SUN OCT 28 2012 .SYNOPSIS... HURRICANE SANDY IS CURRENTLY 350 MILES EAST OF CHARLESTON SOUTH CAROLINA. THE STORM FORECAST TO TRACK TO A POSITION OFF THE VIRGINIA CAPES EARLY MONDAY MORNING...BEFORE TURNING NORTHWEST AND MOVING TOWARD THE DELAWARE BAY EARLY TUESDAY. THE STORM WILL THEN TRACK WEST INTO SOUTH-CENTRAL PENNSYLVANIA TUESDAY AFTERNOON. THIS STORM WILL BRING SIGNIFICANT IMPACTS TO THE REGION TODAY THROUGH THROUGH LATE TUESDAY. THE LOW PRESSURE SYSTEM WILL THEN PERSIST OVER THE NORTHERN MID ATLANTIC STATES THROUGH WEDNESDAY. HIGH PRESSURE IS EXPECTED TO RETURN TO THE REGION LATE IN THE WEEK. && .NEAR TERM /TODAY/... 06Z IAD BALLOON DATA IS IN. UPGRADING TO A HIGH WIND WARNING FOR THE ENTIRE CWA. NORTH- CENTRAL MD TO COASTAL ZONES /ADJACENT TO WATER/ STARTS 12Z MONDAY AND THE REST OF THE CWA STARTS AT 16Z. CRITERIA FOR HIGH WIND WARNING IS 50 KT GUSTS...THOUGH THIS START TIME IS BASED ON ANTICIPATED ADVISORY CRITERIA WINDS /40 KT/ AS IT WOULD BE BEST TO HAVE JUST ONE WIND HEADLINE...PARTICULARLY WITH 50KT VERY POSSIBLE BY THE END OF THE MONDAY PERIOD. PLEASE SEE NPWLWX FOR DETAILS. Link to comment Share on other sites More sharing options...
wxmeddler Posted October 28, 2012 Share Posted October 28, 2012 Amazing: Never in my life, would I thought I'd see this: Especially all at once. This if for Harrisburg btw, but still amazing. A couple of things to point out... 1. The 97 kts at 850 mb 2. The 0-3 km Helicity is 2420 m^2/s^2 3. The Super Saturation layer between 500mb and 700 mb (Dew Point > Temperature) 5. The super saturation layer max difference being Dp>Td by .7°C (1.3°F) 6. Omega max ~ 45 at 400mb 7. Omega > 30 in the super saturation layer. 8. Warm cloud depth @ 12,500 ft. (~580mb) 8. PW @ 1.77" Just mind-blowing. Link to comment Share on other sites More sharing options...
andyhb Posted October 28, 2012 Share Posted October 28, 2012 Haha that helicity reading is just laughably crazy. Link to comment Share on other sites More sharing options...
Ellinwood Posted October 28, 2012 Share Posted October 28, 2012 Haha that helicity reading is just laughably crazy. Indeed. 10x normal for a decent tornado chance. If only there was instability... tornado city. Link to comment Share on other sites More sharing options...
EasternUSWX Posted October 28, 2012 Share Posted October 28, 2012 So the GFS actually has more rain that the NAM for once. Also.. pure hell right there. Link to comment Share on other sites More sharing options...
Jebman Posted October 28, 2012 Share Posted October 28, 2012 http://forecast.weather.gov/product.php?site=NWS&issuedby=LWX&product=AFD&format=CI&version=1&glossary=1&highlight=off HIGH WINDS WILL BE ANOTHER BIG ISSUE...WITH SUSTAINED WINDS RANGING FROM 30 TO AS HIGH AS 45 MPH WITH GUSTS TO 60 MPH. WHERE MAX WINDS OCCUR DEPENDS UPON THE STORM TRACK AND HOW THE TRANSITION TO AN EXTRATROPICAL STORM OCCURS. GFS BUFKIT SHOWS WINDS AT BWI NW AT 100 KTS AT FL 040 AT 2 AM TUE. THE COMBO OF HVY RAINS AND HIGH WINDS ARE A DANGEROUS COMBINATION REGARDING DOWNED TREES/POWER LNS. ONLY SILVER LINING IS THAT LEAVES ARE EITHER DOWN OR WL BE COMING DOWN PSBLY LESSENING TREE DAMAGE. Link to comment Share on other sites More sharing options...
KAOS Posted October 28, 2012 Share Posted October 28, 2012 100 KTS = 114.7899943321674 MPH Link to comment Share on other sites More sharing options...
Stebo Posted October 28, 2012 Share Posted October 28, 2012 Amazing: Never in my life, would I thought I'd see this: Especially all at once. This if for Harrisburg btw, but still amazing. A couple of things to point out... 1. The 97 kts at 850 mb 2. The 0-3 km Helicity is 2420 m^2/s^2 3. The Super Saturation layer between 500mb and 700 mb (Dew Point > Temperature) 5. The super saturation layer max difference being Dp>Td by .7°C (1.3°F) 6. Omega max ~ 45 at 400mb 7. Omega > 30 in the super saturation layer. 8. Warm cloud depth @ 12,500 ft. (~580mb) 8. PW @ 1.77" Just mind-blowing. So what you are saying is that it might rain there? Pretty incredible sounding though, those Omegas are off the charts and that is one hell of a deep warm cloud depth. Link to comment Share on other sites More sharing options...
EasternUSWX Posted October 28, 2012 Share Posted October 28, 2012 6Z GFS has sustained winds at surface 30-40KTS. 925MB are 70KTS+ and 850MB Over 90KTS. Link to comment Share on other sites More sharing options...
EasternUSWX Posted October 28, 2012 Share Posted October 28, 2012 Do I see a 100KTS marker.. dang. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.