yoda Posted October 29, 2012 Share Posted October 29, 2012 Link to comment Share on other sites More sharing options...
usedtobe Posted October 29, 2012 Author Share Posted October 29, 2012 Someone was mentioning on Twitter that extreme blocking makes the forecast easier. Agree? Yes, it also made the feb 5-6, 2010 storm easier to forecast. Still there was the possibility for awhile of Sandy escaping and then a noreaster developing along the frontal zone. Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted October 29, 2012 Share Posted October 29, 2012 Yoda, Essentially the graph shows you how many standard deviations the forecast winds are from the average winds at that time of year. If the distribution is bell shaped, the 6 standard deviation wind field means this is a very rare event and that the 850 winds are rarely ever this strong at this time of year at the location where the winds are show. The math of that statement is mind blowing. 6 sd above normal? I've never seen a z-score table go that high, but the probability of a data point being there has got to be somewhere in the 1 in a 1,000,000 category. Link to comment Share on other sites More sharing options...
chris87 Posted October 29, 2012 Share Posted October 29, 2012 The math of that statement is mind blowing. 6 sd above normal? I've never seen a z-score table go that high, but the probability of a data point being there has got to be somewhere in the 1 in a 1,000,000 category. you have to be careful because that SD is computed from probably a 30-year sample which is pretty limited...extreme events can have large SDs over limited samples but if you had a more substantial sample it probably wouldn't be as high Link to comment Share on other sites More sharing options...
usedtobe Posted October 29, 2012 Author Share Posted October 29, 2012 The math of that statement is mind blowing. 6 sd above normal? I've never seen a z-score table go that high, but the probability of a data point being there has got to be somewhere in the 1 in a 1,000,000 category. If it's a bell curve that is true but the distribution probably isn't one. I know for moisture flux it is very skewed with a long tail on one side and a short one on the other so it isn't as high as 1 in a million. We actually did return frequency on 5 SD events for MF and it was no where near 100 year event. Link to comment Share on other sites More sharing options...
nj2va Posted October 29, 2012 Share Posted October 29, 2012 Courtesy of NE forum: Courtesy of SRAIN: Live report from NOAA P-3 outbound reporting 70kt surface/100kt flight level 175 miles SW of center while heading back to Mac Dill. Report stated wind field expanding as well. Link to comment Share on other sites More sharing options...
thunderman Posted October 29, 2012 Share Posted October 29, 2012 The math of that statement is mind blowing. 6 sd above normal? I've never seen a z-score table go that high, but the probability of a data point being there has got to be somewhere in the 1 in a 1,000,000 category. feast your eyes on this. ~9 SD on the MSLP chart. Link to comment Share on other sites More sharing options...
KAOS Posted October 29, 2012 Share Posted October 29, 2012 In winter this is where it keeps going ne past forecast before clobbering boston. Yah, I give this statement a thumbs up. Thinking the same thing. Not going to happen. Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted October 29, 2012 Share Posted October 29, 2012 Wes and Chris, I guess I immediately thought of a normally distributed set of data. Thanks for your replies. Stats is a little fuzzy area for me as I rarely have to deal with it. Link to comment Share on other sites More sharing options...
usedtobe Posted October 29, 2012 Author Share Posted October 29, 2012 The math of that statement is mind blowing. 6 sd above normal? I've never seen a z-score table go that high, but the probability of a data point being there has got to be somewhere in the 1 in a 1,000,000 category. Here's a return frequency of moisture flux which simply is the wind times the mixing ratio at 850 mb. Note how the return frequency for 6 SD. It is probably different for winds but the same thing holds. Link to comment Share on other sites More sharing options...
Symblized Posted October 29, 2012 Share Posted October 29, 2012 Because the center of the storm is still moving to the NE? From NWS Mount Holly: THE RAIN SHIELD TO THE NORTHWEST OF THE CENTER CONTINUES TO SLOWLY BACK INLAND, HOWEVER A FRONTAL BOUNDARY AT THE SURFACE DRAPED NOT TO FAR TO OUR WEST REMAINS AND APPEARS TO BE PARTIALLY RESPONSIBLE FOR A NORTH-SOUTH ORIENTATED BAND OF ENHANCED RAINFALL. THIS NEARLY LOOKS TO BE SOME SORT OF DEFORMATION AXIS THAT HAS SETUP FOR THE TIME BEING AND MAY MARK THE LOCATION OF WHERE THE HEAVIEST RAIN ENDS UP PIVOTING LATER ON. Link to comment Share on other sites More sharing options...
thunderman Posted October 29, 2012 Share Posted October 29, 2012 you have to be careful because that SD is computed from probably a 30-year sample which is pretty limited...extreme events can have large SDs over limited samples but if you had a more substantial sample it probably wouldn't be as high Exactly. The statistical plots are useful, but you have be realize that the data sets are somewhat limited. While 5SD is significant, it is considerably less significant against a 30 year data set that it is against a hypothetical 100 or 150 year data set. Link to comment Share on other sites More sharing options...
chris87 Posted October 29, 2012 Share Posted October 29, 2012 Wes and Chris, I guess I immediately thought of a normally distributed set of data. Thanks for your replies. Stats is a little fuzzy area for me as I rarely have to deal with it. no prob....events like this don't fit into a normal distribution very well (at least given our limited observational record)...so in general we don't have the record to really accurately quantify how anomalous an event like this actually is Link to comment Share on other sites More sharing options...
thunderman Posted October 29, 2012 Share Posted October 29, 2012 If it's a bell curve that is true but the distribution probably isn't one. I know for moisture flux it is very skewed with a long tail on one side and a short one on the other so it isn't as high as 1 in a million. We actually did return frequency on 5 SD events for MF and it was no where near 100 year event. I am curious, what was the closest to 100 years that you got? Link to comment Share on other sites More sharing options...
Absolute Humidity Posted October 29, 2012 Share Posted October 29, 2012 Is it just me or is the NAM going to be south? Link to comment Share on other sites More sharing options...
nj2va Posted October 29, 2012 Share Posted October 29, 2012 Is it just me or is the NAM going to be south? Definitely looks that way through 15. Link to comment Share on other sites More sharing options...
usedtobe Posted October 29, 2012 Author Share Posted October 29, 2012 Is it just me or is the NAM going to be south? I don't remember, Remember our data set was only using the reanalysis data which 60 years of data but based on a 30 year mean (If I remember correctly) There was a pretty good correlation between the major ca rainfall events and the high MF anomaly values. Of course CA events are modulated strongly by terrain and having moisture plumes or atmospheric rivers running into the coastal ranges and sierra range. Link to comment Share on other sites More sharing options...
usedtobe Posted October 29, 2012 Author Share Posted October 29, 2012 Definitely looks that way through 15. I don't think landfall was much different. Link to comment Share on other sites More sharing options...
nj2va Posted October 29, 2012 Share Posted October 29, 2012 I don't think landfall was much different. Yeah, it seemed it was heading south but looks to be pretty much the same at landfall. Link to comment Share on other sites More sharing options...
caviman2201 Posted October 29, 2012 Share Posted October 29, 2012 Found this on Accuweather... not sure if the source validates it or not, though... 8:30 p.m. EDT: The fishing pier in Ocean City, Md. has been damaged and may collapse during the next round of high tides Monday. http://www.accuweather.com/en/weather-news/updates-sandys-catastrophic-im/746423 Link to comment Share on other sites More sharing options...
Jebman Posted October 29, 2012 Share Posted October 29, 2012 Interesting info in latest AFD thus far --- I am archiving this 000 FXUS61 KLWX 290112 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 912 PM EDT SUN OCT 28 2012 .SYNOPSIS... HURRICANE SANDY REMAINS ABOUT 475 MILES SOUTHEAST OF WASHINGTON D.C. THE STORM IS FORECAST TO CURVE TOWARD THE COAST ON MONDAY...AND MOVE INLAND NEAR THE JERSEY SHORE MONDAY NIGHT. THE POST-TROPICAL CYCLONE WILL THEN SLOWLY TRACK INLAND INTO PENNSYLVANIA. THIS LARGE STORM WILL BRING SIGNIFICANT IMPACTS TO THE ENTIRE REGION THROUGH MIDWEEK. CONDITIONS WILL IMPROVE FOR THE SECOND HALF OF THE WORK WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... FCST TNGT REMAINS ON TRACK. SANDY MOVING TO THE NORTHEAST TONIGHT... REMAINING WELL OFF THE COAST OF SOUTHEAST VIRGINIA BEFORE SWINGING BACK TO THE NORTHWEST MONDAY AND MONDAY NIGHT AND MAKING LANDFALL ALONG THE JERSEY SHORE EARLY TUESDAY. PLEASE CONTINUE TO REFER TO THE LATEST ADVISORIES FROM THE NATIONAL HURRICANE CENTER FOR UPDATES TO THE POSITION/TRACK OF SANDY. RAIN HAS BEEN ALIGNED ALONG THE EASTERN SHORE OF MARYLAND THROUGH MUCH OF THE DAY WITH LITTLE WESTERN MOVEMENT. A GRADUAL WWD DRIFT HAS BEGUN. WITH THE NE FLOW AND SUBTLE NOCTURNAL COOLING...ALSO HV LGT RA/DZ FILLING IN ACRS THE REST OF THE AREA. STILL XPCT MDT RAIN TO MV WWD ACRS CWFA OVNGT...SPCLY FOR CNTYS E OF THE BLURDG. WINDS WILL ALSO CONTINUE TO INCREASE THROUGHOUT THE NIGHT...LIKELY REACHING 40 TO 45 MPH PRIOR TO DAYBREAK. ALREADY HV 40-45 KT GUSTS INVOF HAMPTON ROADS. THESE WNDS SHUD SPREAD WWD ACCOMPANYING THE RAFL. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... AT THE START OF MONDAY...THE CENTER OF SANDY IS FORECAST TO BE AROUND 400 MILES EAST-SOUTHEAST OF WASHINGTON. HOWEVER...AS WE HAVE BEEN STRESSING...THIS IS AN EXPANSIVE STORM AND SO CONDITIONS /WHICH ARE ALREADY BREEZY WITH RAIN SPREADING WEST OVER THE BAY/ WILL CONTINUE TO DETERIORATE DURING THE DAY MONDAY...AND KEEP GOING DOWNHILL AFTER THAT. ALL THE DETAILS OF THE FORECAST ARE IN OUR GRAPHICAL AND TEXT FORECAST PRODUCTS...BUT JUST AS A SUMMARY OF WHAT TO EXPECT: RAINFALL/FLOODING...WILL BE DISCUSSED IN HYDROLOGY SECTION BELOW. FLOOD THREAT IS SIGNIFICANT SO PLEASE REFER TO THAT. WINDS...WE ARE ALREADY GUSTING TO 30 MPH AT TIMES IN SPOTS...AND THAT WILL BE CONTINUING TO INCREASE. WE ARE EXPANDING THE HIGH WIND WARNING TO START AT 8 AM MONDAY IN ALL AREAS...THOUGH IN SOME OF THE WESTERN VALLEYS IT MAY STILL BE CLOSER TO NOON. A PROLONGED PERIOD OF POWERFUL AND DANGEROUS WINDS IS EXPECTED...LASTING LIKELY WELL INTO TUESDAY BEFORE GRADUALLY SUBSIDING. THIS PROLONGED PERIOD OF WINDS WILL DO DAMAGE AND CREATE POWER OUTAGES. SNOWFALL...YES...SNOWFALL. XPCT COLD AIR TO WRAP ARND THE SWRN SIDE OF THE STORM...BUT HV BEEN WRESTLING WITH HOW MUCH. THERMALLY CONDS LOOK MARGINAL...BUT DYNAMICALLY IT LOOKS IDEAL. IN THE END CANNOT IGNORE BUFKIT PTYPE OUTPUT NOR SREF GDNC ALL POINTING TO COPIOUS SNOW. HV CONVERTED WINTER STORM WATCH TO A BLIZZARD WARNING. THIS WL BE A DANGEROUS COMBO AS HEAVY SNOW WL BE COMBINED WITH STRONG WINDS. EAST OF THE WESTERN FRONT...THE SNOW THREAT IS EXTREMELY LOW. WL BE RUNNING WITH 6-12 INCHES THROUGH TUE. THERE SHUD BE ADDTL ACCUMS IN UPSLOPE FLOW BYD THAT. TIDAL/COASTAL FLOODING...WILL BE DISCUSSED IN TIDAL/COASTAL SECTION BELOW. THIS THREAT IS VERY COMPLEX SO REFER TO THAT SECTION FOR A DETAILED DISCUSSION. BOTTOM LINE...THIS IS A VERY DANGEROUS STORM WHICH WILL AFFECT THE ENTIRE AREA REGARDLESS OF WHERE THE STORM CENTER IS. PLEASE REFER TO THE SUITE OF HAZARDOUS WEATHER BULLETINS/WARNINGS FOR EVEN MORE INFORMATION ABOUT THE IMPENDING STORM. ALSO PLEASE TAKE THIS THREAT VERY SERIOUSLY...THIS IS GOING TO CREATE SIGNIFICANT DISRUPTIONS OVER THE NEXT COUPLE DAYS. BE PREPARED TO AT LEAST HUNKER DOWN FOR A WHILE...AND BE PREPARED FOR SOME SERIOUSLY CHALLENGING CONDITIONS. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... THE MAIN WEATHER STORY IN THE EXTENDED IS THE POTENTIAL FOR A PROLONGED UPSLOPE PERIOD IN THE FAR WEST. WHILE THE INTENSITY OF SUCH AN EVENT WOULD BE ABSOLUTELY NOTHING COMPARED TO THE EARLY PART OF THE WEEK...IT KEEPS THE LIGHT PRECIP MACHINE TURNED ON...PROBABLY THROUGH THURSDAY OR FRIDAY. THERE IS A SMALL RISK OF PRECIPITATION MAKING IT EVEN BEYOND THE WESTERN FRONT INTO THE REST OF THE HIGHLANDS...MAYBE EVEN UP TO THE BLUE RIDGE. FOR EVERYONE ELSE...THE EXTENDED PERIOD WILL BE THE CALM AFTER THE STORM. TEMPERATURES WILL BE 5 TO 10 DEGREES BELOW NORMAL THROUGHOUT THE PERIOD...WITH HIGHS MAINLY IN THE 50S IN LOWS IN THE UPPER 30S TO AROUND 40. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... NORTH/NORTHEAST WINDS WILL CONTINUE TO INCREASE OVER THE NEXT 12-18 HOURS...WITH SIGNIFICANT IMPACT FROM WINDS EXPECTED BEGINNING MONDAY. EXPECT THE HUBS TO HAVE SUSTAINED WINDS ON MONDAY OF 25 TO 35 KT WITH GUSTS REACHING 50 TO 55 KT. SIMILAR OR STRONGER GUSTS ARE EXPECTED MONDAY NIGHT INTO TUESDAY. CIGS/VSBYS DROPPING DUE TO LGT RAIN/DZ IN NELY FLOW. MDT RAIN WILL TILT NORTHWEST...MAKING IT TO THE HUBS OVNGT AND SPREADING ACROSS THE ENTIRE AREA BY MRNG. CONDS HV ALREADY DROPPED TO LOW END MVFR TO HIGH END IFR. WL SEE FLGT CONDS AOB IFR OVNGT THRU THE DAY MON. SEVERE IMPACTS ON AVIATION THROUGH TUESDAY WITH LOW CLOUDS...EXTREME WINDS...AND HEAVY RAIN. CONDITIONS WILL SLOWLY IMPROVE TUESDAY NIGHT AND NO IMPACTS TO AVIATION ARE EXPECTED FOR THE SECOND HALF OF THE WEEK AT THE MAJOR TERMINALS. && .MARINE... HURRICANE FORCE WIND WARNING REMAINS IN EFFECT FOR THE ENTIRE MARYLAND CHESAPEAKE BAY AND ALL THE VARIOUS INLETS...AND FOR THE LOWERMOST PORTION OF THE TIDAL POTOMAC RIVER. IN THIS AREA...GUSTS OF 65 KNOTS ARE POSSIBLE MONDAY AND MONDAY NIGHT. THE UPPER/MIDDLE TIDAL POTOMAC RIVER REMAINS UNDER A STORM WARNING. BOTH OF THESE WARNINGS ARE IN EFFECT THROUGH TUESDAY. WINDS REACHING/EXCEEDING SCA CRITERIA WILL CONTINUE ACROSS THE MARINE AREA THROUGH AT LEAST WEDNESDAY...AND I ACTUALLY HAVE WIND GUSTS MEETING SCA CRITERIA IN AT LEAST A PORTION OF THE WATERS THROUGH MOST OF THE FORECAST PERIOD. HIGH PRESSURE COULD BUILD IN AND WEAKEN THE WIND FIELDS BY NEXT WEEKEND. && .HYDROLOGY... NO CHG TO THOUGHT PROCESS OF RAINFALL FCST. THE LATEST RAINFALL PROJECTIONS HAVE COME IN HIGHER...AND WE WILL NOW SAY THAT 5-9 INCHES OF RAIN IS POSSIBLE IN THE I-270 CORRIDOR THROUGH THE DC METRO AREA AND DOWN THROUGH SOUTHERN MARYLAND. AMOUNTS COULD BE EVEN HIGHER CLOSE TO THE BAY. 3-5 INCHES OF RAIN IS EXPECTED IN THE NORTHERN HIGHLANDS AND RAPPAHANNOCK BASIN...WITH LOWER AMOUNTS OF JUST 1-3 INCHES IN THE STAUNTON/WAYNESBORO/ CHARLOTTESVILLE/HARRISONBURG AREAS. OUR RAINFALL PROJECTIONS HAVE OVER AN INCH OF RAIN PER SIX HOUR PERIOD FOR 24 HOURS IN THE AREA WHERE THE HEAVIEST RAIN IS ANTICIPATED. SOME FLASH FLOODING WOULD OCCUR IF MORE THAN THIS IS EXPECTED...AND IS ALSO POSSIBLE WITH LOWER AMOUNTS IN AREAS WHERE FALLEN LEAVES /OR PERHAPS OTHER WIND-DRIVEN DEBRIS/ MAY CLOG DRAINAGE SYSTEMS. THESE FACTORS ALSO APPLY FOR LONGER-DURATION STREAM FLOODING...WHICH IS LIKELY TO BE SIGNIFICANT AND LENGTHY... EVEN ON STREAMS THAT ARE USUALLY FAST TO RISE AND FALL. THE FLOOD THREAT BEGINS LATE TONIGHT. THE SMALLER STREAM AND URBAN FLOOD THREAT CONTINUES THROUGH TUESDAY. THEN WE TURN ATTENTION TO THE RIVER FORECAST LOCATIONS. AT THIS TIME...FIVE OF THOSE POINTS /CONOCOCHEAGUE...MONOCACY...OPEQUON...SENECA...AND ANTIETAM/ ARE FORECAST TO GO TO FLOOD. WE HAVE BEEN INCLUDING THAT IN THE FLOOD WATCH BUT WARNING DECISIONS WILL LIKELY COME TONIGHT OR TOMORROW IF THE FORECASTS HOLD...WHICH SO FAR...THEY HAVE. IF EVERYTHING PLAYS OUT AS FORECAST...THE CREST MAY NOT GET DOWN TO LITTLE FALLS UNTIL FRIDAY OR SATURDAY. && .TIDES/COASTAL FLOODING... THE TIDAL SITUATION IS VERY COMPLEX AND EVEN A LITTLE BIT CONFUSING. BUT WILL TRY TO BREAK IT DOWN HERE. TIDAL ANOMALIES HAVE BEEN IN THE 1 TO 2 FT RANGE. ADVISORY REMAINS OUT FOR ALEXANDRIA AND THE ENTIRE WESTERN BAY AND LOWER TIDAL POTOMAC. AS THE NORTHERLY/NORTHWESTERLY WINDS INCREASE...WE SHOULD BLOW OUT THE HIGH WATER IN MOST OF OUR TIDAL REGION LATE TONIGHT AND TOMORROW. AT THIS POINT THOUGH...WE WILL LEAVE THE EXISTING ADVISORY IN PLACE UNTIL THE BLOWOUT STARTS. IT CAN ALWAYS BE CANCELLED WHEN IT BEGINS. ONCE THE STORM MOVES INLAND...WINDS WILL TURN OUT OF THE SOUTH LATE MONDAY NIGHT THROUGH TUESDAY NIGHT AND STILL BE QUITE STRONG. THIS WILL PUSH WATER UP THE BAY AND TIDAL POTOMAC...AND AT THAT TIME THE TIDAL FLOOD THREAT MARKEDLY INCREASES. HAVE RAISED A COASTAL FLOOD WARNING FROM MIDNIGHT MONDAY NIGHT THROUGH TUESDAY NIGHT. MODERATE FLOODING IS POSSIBLE. A MAJOR FLOOD IS NOT EXPECTED AT THIS POINT. THE WIND FIELD BEYOND TUESDAY NIGHT IS MUCH MORE UNCERTAIN...SO IT IS NOT YET CLEAR WHETHER WE WILL REMAIN ELEVATED...GRADUALLY DROP... OR PERHAPS BLOW OUT YET AGAIN. && .CLIMATE... PRELIMINARY INFORMATION ON LOWEST PRESSURE RECORDED AT WASHINGTON DC AND BALTIMORE MD...BOTH MEASURED IN THE MARCH 1993 SUPER STORM... WASH DC... 28.54 INCHES HG 966.5 MB MEASURED AT 23Z ON 13 MARCH 1993 BALT MD... 28.52 INCHES HR 965.9 MB MEASURED AT 00Z ON 14 MARCH 1993 THESE VALUES WERE ARRIVED AT BY SEARCHING AN INTERNAL DATABASE OF OBSERVATIONS MAINTAINED UNOFFICIALLY HERE AT THE WEATHER OFFICE. THE DATABASE GOES BACK TO 1929. && This storm is absolutely FASCINATING. Link to comment Share on other sites More sharing options...
Don Cherry's Jacket Posted October 29, 2012 Share Posted October 29, 2012 In winter this is when I get slammed for ruining someones life because the forecast busted. I repeat my commitment to credit CWG for sensible warnings if this fails to turn west and I wake up with power on Wednesday. But, since that won't happen, thanks for your work so far. It has been a great, if terrifying set of information. Link to comment Share on other sites More sharing options...
PhineasC Posted October 29, 2012 Share Posted October 29, 2012 Uh, the GFS... It is a little different... Link to comment Share on other sites More sharing options...
nw baltimore wx Posted October 29, 2012 Share Posted October 29, 2012 Uh, the GFS... It is a little different... I'm stuck at 24 hours but that gradient is even tighter. Link to comment Share on other sites More sharing options...
PhineasC Posted October 29, 2012 Share Posted October 29, 2012 I'm stuck at 24 hours but that gradient is even tighter. It shifted south quite a bit. Looks like a Delaware Bay landfall right into Baltimore. Link to comment Share on other sites More sharing options...
EasternUSWX Posted October 29, 2012 Share Posted October 29, 2012 Yikes. Link to comment Share on other sites More sharing options...
MidlothianWX Posted October 29, 2012 Share Posted October 29, 2012 It shifted south quite a bit. Looks like a Delaware Bay landfall right into Baltimore. Noticed that as well. Precip shield looks a little wacky but it is definitely a shift S/SW. Link to comment Share on other sites More sharing options...
Amped Posted October 29, 2012 Share Posted October 29, 2012 No snow for the nrn 2/3 of WV on the GFS 850 temps like +4. Landfall near Atlantic City. Link to comment Share on other sites More sharing options...
nj2va Posted October 29, 2012 Share Posted October 29, 2012 Windy and wet. 5"+. Link to comment Share on other sites More sharing options...
WVclimo Posted October 29, 2012 Share Posted October 29, 2012 Yep, Atlantic City on the GFS, then rides Rt 40 west until it gets here, where it sits for a day. Link to comment Share on other sites More sharing options...
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