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March 26th Snowstorm - continued discussion and observations


wxsniss

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EC going all in here. Blizzard and storm surge warnings up. 30-40cms(12-16inches) with possibly more. Winds to 70kmh gusts to 110kmh(40-70mph).

 

Here is a link to our local forum for those that may wish to keep tabs. Not as active as here but should pick up as we get closer to go time. Its under the severe weather/storm chat section.

 

http://z7.invisionfree.com/ACOWW/index.php?act=idx

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Do you have any webcams of NS? I want to bookmark it for later on. Thanks. :snowwindow:

 

http://novascotia.ca/tran/cameras/

 

 

Looking forward to looking at the ones around Amherst.

 

My wife's mother is from Cape Breton (Inverness) and we go there every summer.  Beautiful place with great people....

 

This should be good too. Lots of cameras around Moncton

 

https://www.gnb.ca/0113/cameras/cameras-e.asp

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EC going all in here. Blizzard and storm surge warnings up. 30-40cms(12-16inches) with possibly more. Winds to 70kmh gusts to 110kmh(40-70mph).

 

Here is a link to our local forum for those that may wish to keep tabs. Not as active as here but should pick up as we get closer to go time. Its under the severe weather/storm chat section.

 

http://z7.invisionfree.com/ACOWW/index.php?act=idx

Enjoy it man!

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BOX AM AFD

 

 

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
HIGHLIGHTS...
* LOW CONFIDENCE FORECAST W/DEVELOPING OCEAN STORM
* POTENTIAL BLIZZARD WITH DAMAGING WINDS POSSIBLE FOR CAPE/ISLANDS
* SHARP CUTOFF IN SIGNIFICANT SNOWFALL EXPECTED IN THE BOSTON TO
PROVIDENCE CORRIDOR WITH LITTLE TO NO IMPACT WELL INLAND

MODEL PREFERENCES AND SYNOPTIC OVERVIEW...00Z MODELS REMAIN IN GOOD
AGREEMENT ON EXPLOSIVE AND RAPID BOMBOGENESIS SOUTH OF NEW
ENGLAND LATE TONIGHT INTO WED. THE DIFFERENCES ARE IN THE
EVOLUTION/TRACK AND STRUCTURE OF THIS POWERFUL OCEAN STORM. TWO
DISTINCT CAMPS OF MODEL SOLUTIONS HERE WITH THE NAM AND ECMWF
STRONGER AND PIVOT SYSTEM FARTHER TO THE NORTHWEST. MEANWHILE THE
GFS/UKMET/RGEM AND GEFS ARE FARTHER EAST WITH LESS PIVOTING. THE
ECMWF HAS SHOWN THE BEST RUN TO RUN CONTINUITY WITH THIS SYSTEM
FOR MANY DAYS NOW AND IS A NICE COMPROMISE BETWEEN THE
STRONGER/WESTWARD NAM AND THE FARTHER EAST GFS/UKMET/RGEM AND
GEFS. WILL BASE THIS FORECAST ON A MODEL BLEND TO INCORPORATE THE
LARGE MODEL SPREAD BUT GIVE MORE WEIGHT TO THE CONSISTENT ECMWF.

FORECAST ISSUES/UNCERTAINTY...ONE OF THE ISSUES WITH THIS POWERFUL
OCEAN STORM IS THAT IT/S DEVELOPING AWAY FROM THE BAROCLINIC ZONE
AND MORE IN THE WARM SECTOR. CONVECTION AND PROXIMITY TO THE GULF
STREAM LIKELY A PLAYER HERE. HOW MODELS SIMULATE OFFSHORE CONVECTION
AND ASSOCIATED EXPLOSIVE INTENSIFICATION WILL BE KEY ON THE
EVOLUTION AND STRUCTURE OF THIS STORM. ANY TIME A SHARP QPF GRADIENT
IS PLACED OVER THE REGION BUST POTENTIAL IS VERY LARGE AS A SMALL
SHIFT IN THE QPF SHIELD WILL HAVE A LARGE IMPACT ON SNOWFALL. FOR
THESE REASONS FORECAST CONFIDENCE IS SOMEWHAT BELOW AVERAGE GIVEN
THE RELATIVELY SHORT TIME RANGE HERE. THUS CONFIDENCE IS NOT HIGH
ENOUGH TO UPGRADE ANY WATCHES TO WARNINGS. GIVEN POTENTIAL HEAVY
SNOW AND STRONG WINDS NOT EXPECTED UNTIL LATE SECOND PERIOD
/LATE TONIGHT/ AND BULK OF EVENT IN EARLY 3RD PERIOD /WED
MORNING/...FEEL THERE IS STILL SOME TIME TO MONITOR MODEL TRENDS
BEFORE LOCKING THE FORECAST INTO ONE GIVEN MODEL SOLUTION.
FURTHERMORE LOOKING AT TWO DRY COMMUTES /THIS MORNING AND THIS
EVENING/ BEFORE ANY POTENTIAL WEATHER IMPACTS ARRIVE ACROSS THE
REGION.

STRONG WIND/DAMAGING WIND POTENTIAL...THE WORSE CASE SCENARIO IS THE
00Z NAM WITH ITS SOUNDINGS SUGGESTING 60-70 MPH /APPROACHING
HURRICANE FORCE/ ACROSS CAPE COD AND NANTUCKET. CONVERSELY THE
WEAKER GFS YIELDING 50-60 MPH. A MODEL BLEND OFFERS NORTH WINDS
GUSTING UP TO 60 MPH WHICH WOULD SUPPORT A MODERATE RISK OF DAMAGING
WINDS. THE BLIZZARD WATCH HIGHLIGHTS THIS WITH GUSTS OVER 35 MPH.
HOWEVER AS PREVIOUS FORECASTER MENTIONED WIND SPEEDS APPROACHING 60
MPH SUBSTANTIALLY INCREASE THE RISK OF WIND DAMAGE AND POWER
OUTAGES. FOR THIS REASON WILL ISSUE A HIGH WIND WATCH TO
COMMUNICATE THE MODERATE RISK OF DAMAGING WINDS/POWER
OUTAGES...WHERE THE BLIZZARD WATCH WILL CONVEY THE LOW
VSBY/BLOWING AND DRIFTING SNOW.

SNOWFALL...GIVEN THE LARGE MODEL SPREAD FORECAST CONFIDENCE IN
SNOWFALL IS BELOW AVERAGE. AS MENTIONED ABOVE TO INCORPORATE THIS
MODEL SPREAD DID A BLEND OF QPF WITH MORE WEIGHT GIVEN TO THE
CONSISTENT 00Z ECMWF. THIS YIELDS VERY LITTLE CHANGE FROM OUR
PREVIOUS SNOW FORECAST WITH 2-4 INCHES IN THE BOSTON TO PROVIDENCE
CORRIDOR...4 TO 6 INCHES ACROSS SOUTHEAST MA AND 6-10 INCHES OVER
CAPE COD AND THE ISLANDS. STRONG TO DAMAGING WINDS WILL YIELD
CONSIDERABLY BLOWING AND DRIFTING SNOWFALL. PROGRESSIVE NATURE OF
SYSTEM WILL PRECLUDE A LONGER DURATION SNOWSTORM.

ONSET OF SNOW...SNOW OVERSPREADS THE REGION 03Z-09Z.

HEAVIEST SNOW...09Z-18Z THEN TAPERING OFF FROM WEST TO EAST. WED
MORNING COMMUTE WILL LIKELY BE IMPACTED ESPECIALLY OVER SOUTHEAST MA
WITH LESS IMPACT NORTHWEST OF PROVIDENCE TO BOSTON. GIVEN THE COLD
AIRMASS IN PLACE EXPECTING A RATHER FLUFFY/DRY SNOWFALL. THIS WILL
ENHANCE THE BLOWING AND DRIFTING POTENTIAL ACROSS SOUTHEAST MA
ESPECIALLY CAPE COD AND THE ISLANDS.

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Good discussion, not much else they can do at this point except wait for a little better agreement from US guidance.

If they handed out oscars for meltdowns I may have gotten one last night. That was Steve Allen planes trains and automobiles 4 F'ing wheels and a seat worthy.

I can never recall distinct model branches wavering so wildly in this close. As KTAN put it, it all comes down to the shake and bake. The miss models did not have enough. 6z rgem I think was the biggest hit of the rgem runs yet. 6z gfs was one of it's bigger. Nam backed off slightly but still solid and the euro was good.

My guess is it's still data going in somehow. IE either due to resolution or algo changes models can have high run to run variability and lose continuity. The 0z rgem was such a break from previous guidance at init only to correct at 6z init it almost has to be inputs. It's remarkable to me that we see these differences and it's not convective because the problems are immediate long before convection fires.

Anyway hopefully we aren't about to get charlie browned down here. Seems like an almost all or nothing proposition. With my meltdown out of the way I can enjoy today.

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Btw agree with Taunton for down here. They really have no choice how can you go against the euro with nam support and 6z rgem?

You can't at this point, this close in.

We will be able to look at the current surface analysis in 6 hours and have a better idea which models were correct, if any, in the extent of the convective push East of Florida.

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Btw agree with Taunton for down here. They really have no choice how can you go against the euro with nam support and 6z rgem?

 

I agree but I am leery of this thing pulling that Charlie Brown too.  I think you need to weigh the higher resolution models(global and meso) a bit more given the nature of this system.

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I agree but I am leery of this thing pulling that Charlie Brown too. I think you need to weigh the higher resolution models(global and meso) a bit more given the nature of this system.

The RAP really wants to separate the lows early down south, but it's been keeping the west one dominant enough to affect SNJ like the NAM, albeit at end of it's range.

Hard to blame BOX for their current map even if they bust. One of those days that will need constant updating though.

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If they handed out oscars for meltdowns I may have gotten one last night. That was Steve Allen planes trains and automobiles 4 F'ing wheels and a seat worthy.

I can never recall distinct model branches wavering so wildly in this close. As KTAN put it, it all comes down to the shake and bake. The miss models did not have enough. 6z rgem I think was the biggest hit of the rgem runs yet. 6z gfs was one of it's bigger. Nam backed off slightly but still solid and the euro was good.

My guess is it's still data going in somehow. IE either due to resolution or algo changes models can have high run to run variability and lose continuity. The 0z rgem was such a break from previous guidance at init only to correct at 6z init it almost has to be inputs. It's remarkable to me that we see these differences and it's not convective because the problems are immediate long before convection fires.

Anyway hopefully we aren't about to get charlie browned down here. Seems like an almost all or nothing proposition. With my meltdown out of the way I can enjoy today.

Don't worry, I think we all had a little meltdown last night. Models gave me nightmares last night. 

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Wonder if this has a trick or two up its sleeve for SE MA either way.

 

I absolutely believe the tricks are coming.  This one is a nightmare for you guys.  For us it's fun, for forecasters this one is like the running of the bulls.

 

I agree but I am leery of this thing pulling that Charlie Brown too.  I think you need to weigh the higher resolution models(global and meso) a bit more given the nature of this system.

 

The 6z GFS and RGEM came way back which makes me think it was a bad initialization somehow at 0z.  If you remove that single run, the multi run trend in those models was positive.  Something bad got in at init IMO and was missed on the QC. 

 

Even the GFS has incredible conditions for them tomorrow morning. That is the spot to be. GFS gusts them close to hurricane force. 

 

6z GFS was one of its best runs.

 

Scott where do you get 6Z rgem 30 hr progs,hard to tell what exactly transpires,also GGEM was solid for you

 

Steve just looking at the B&W on the main site.  I didn't spend much time but it went from basically nothing on the 0z to pushing the 10mm back to me and the 25mm tickling Chatham for 12 hours in one run so it clearly dramatically improved.

 

Don't worry, I think we all had a little meltdown last night. Models gave me nightmares last night. 

 

Epic fake out.  I assumed everything prior to the 0z was on the sauce, appears whatever got into some of the models at 0z washed out at 6z...or at least I hope that was the case. 

 

Take a look at the 6z GFS 0h at 500 vs the 6h 0z GFS.  For a 6 hour prog those are really significant changes in strength and placement of the features.  Note also the GFS took the vorticity down a few notches over Florida which seemed to be a big part of this.

 

I actually expect some significant moves at 12z. 

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I absolutely believe the tricks are coming.  This one is a nightmare for you guys.  For us it's fun, for forecasters this one is like the running of the bulls.

 

 

The 6z GFS and RGEM came way back which makes me think it was a bad initialization somehow at 0z.  If you remove that single run, the multi run trend in those models was positive.  Something bad got in at init IMO and was missed on the QC. 

 

 

6z GFS was one of its best runs.

 

 

Steve just looking at the B&W on the main site.  I didn't spend much time but it went from basically nothing on the 0z to pushing the 10mm back to me and the 25mm tickling Chatham for 12 hours in one run so it clearly dramatically improved.

 

 

Epic fake out.  I assumed everything prior to the 0z was on the sauce, appears whatever got into some of the models at 0z washed out at 6z...or at least I hope that was the case. 

 

Take a look at the 6z GFS 0h at 500 vs the 6h 0z GFS.  For a 6 hour prog those are really significant changes in strength and placement of the features.  Note also the GFS took the vorticity down a few notches over Florida which seemed to be a big part of this.

 

I actually expect some significant moves at 12z. 

 

I absolutely believe the tricks are coming.  This one is a nightmare for you guys.  For us it's fun, for forecasters this one is like the running of the bulls.

 

 

The 6z GFS and RGEM came way back which makes me think it was a bad initialization somehow at 0z.  If you remove that single run, the multi run trend in those models was positive.  Something bad got in at init IMO and was missed on the QC. 

 

 

6z GFS was one of its best runs.

 

 

Steve just looking at the B&W on the main site.  I didn't spend much time but it went from basically nothing on the 0z to pushing the 10mm back to me and the 25mm tickling Chatham for 12 hours in one run so it clearly dramatically improved.

 

 

Epic fake out.  I assumed everything prior to the 0z was on the sauce, appears whatever got into some of the models at 0z washed out at 6z...or at least I hope that was the case. 

 

Take a look at the 6z GFS 0h at 500 vs the 6h 0z GFS.  For a 6 hour prog those are really significant changes in strength and placement of the features.  Note also the GFS took the vorticity down a few notches over Florida which seemed to be a big part of this.

 

I actually expect some significant moves at 12z. 

Luckily I have no responsibility for this one. Will be interesting to see unfold for you guys and the Cape.

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