Apr 29-30 MidAtl/NE Storm, Reality: Short Range (0-3 Days Out) Forecasts Options

[LoveNYCSnow]

Still north on the 0z as with the 18z and 12z runs, although it does take a small step towards the consensus by shifting slightly south and a bit colder... it's the lone outlier now, even the SREF backed away. Now the question is will the NAM cave in, or will it somehow end up as the start of a new trend? Impossible to know for sure, but trends this year favor the first option.

NAM always overdoes qpf and snowfall amounts, however I do think some wet snowflakes I80 north in PA can not be ruled out and then around I84 in NYS and Conn if the precip is able to get that far north.

This post has been edited by LoveNYCSnow: Apr 26 2012, 09:52 PM

[NYCSuburbs]

NAM always overdoes qpf and snowfall amounts, however I do think some wet snowflakes I80 north in PA can not be ruled out and then around I84 in NYS and Conn if the precip is able to get that far north.

Perhaps in parts of PA, but I doubt precipitation gets into Connecticut with the strong low in SE Canada suppressing the storm. The latest NAM run also showed more of an ESE movement as opposed to an east movement, taking it one step closer to the rest of the models that also keep it suppressed south of New England.

[LUCC]

Looks like some showers for the Mason Dixon Line on north and steadier rain to the south.

[NYCSuburbs]

The NAM just couldn't be any more predictable... next up it should back a little bit more to the south and that's about it probably.

[LoveNYCSnow]

The NAM just couldn't be any more predictable... next up it should back a little bit more to the south and that's about it probably.

NAM really is a joke, there is something wrong with that model, always showing decent snowstorms and then being wrong all winter and even now into the spring. They really should look into it.

[NYCSuburbs]

NAM really is a joke, there is something wrong with that model, always showing decent snowstorms and then being wrong all winter and even now into the spring. They really should look into it.

It seems to me that it happened more frequently since its last upgrade... this problem did exist prior to the upgrade, and there were some problems that I saw before and almost never see now such as the NAM taking tiny areas of convection and blowing them up into a sub-1000mb low pressure, but hopefully the next upgrade will include this problem as well. It's been doing this since the fall with snowstorms, as it even overestimated the October storm.

[grandpaboy]

NAM really is a joke, there is something wrong with that model, always showing decent snowstorms and then being wrong all winter and even now into the spring. They really should look into it.

And yet still till this day people still hang on to this model seeing a monster storm(rain or snow) is coming............even with the constant horrible record it has had since last OCT............

[Superstorm93]

Unfortunately, the NAM 12km doesn't have any big upgrades scheduled for the next few months. It's 4km counterpart does have some things planned.

The GFDL, HWRF, and GFS all do. The GFS upgrade will be "major" and will definitely affect it's performance for the upcoming hurricane season and winter

[NYCSuburbs]

The GFDL, HWRF, and GFS all do. The GFS upgrade will be "major" and will definitely affect it's performance for the upcoming hurricane season and winter

The GFS definitely needs it... the NAM is also in need of an upgrade IMO but given that it's a short range model it should be expected that it will have some issues in the hour 60-84 time range.

[grandpaboy]

Unfortunately, the NAM 12km doesn't have any big upgrades scheduled for the next few months. It's 4km counterpart does have some things planned.

The GFDL, HWRF, and GFS all do. The GFS upgrade will be "major" and will definitely affect it's performance for the upcoming hurricane season and winter

The GFS changes are noted as "major"............

"The primary change to the operational GFS and GDAS will be in the analysis system. The major component of the analysis change will be the incorporation of a hybrid variational/ensemble assimilation system. In this system, the background error used to project the information in the observations into the analysis is created by a combination of a static background error (as in the prior system) and a new background error produced from a lower resolution (T254) Ensemble Kalman Filter. The development of this system was done in collaboration with PSD at ESRL. The inclusion of this change and the other smaller changes listed below produce significant positive impact on forecasts in both the northern and southern hemispheres and in the tropics."

though they went on with this as well........

"GFS Model Changes:
The global spectral model is restructured, but there are no major physics or dynamics changes except for some bug fixes"

we shalll see.............

[SyracuseSnow]

The GFS changes are noted as "major"............

"The primary change to the operational GFS and GDAS will be in the analysis system. The major component of the analysis change will be the incorporation of a hybrid variational/ensemble assimilation system. In this system, the background error used to project the information in the observations into the analysis is created by a combination of a static background error (as in the prior system) and a new background error produced from a lower resolution (T254) Ensemble Kalman Filter. The development of this system was done in collaboration with PSD at ESRL. The inclusion of this change and the other smaller changes listed below produce significant positive impact on forecasts in both the northern and southern hemispheres and in the tropics."

though they went on with this as well........

"GFS Model Changes:
The global spectral model is restructured, but there are no major physics or dynamics changes except for some bug fixes"

we shalll see.............

The major changes aren't to the physical or dynamic aspect of the model. The data assimilation is improved and I remember seeing somewhere that when the GFS was initialized with the ECM data, it produced much better results. It should be interesting to see how big of an improvement this makes.

[AngeloinSJ]

Minimum temps for this time frame. I havent checked max.

Coldest for GFS on left(Sun. morn). Coldest for NAM on right.(Sat morn)

[attachment=162425:temps29.jpg]

Wow well actually last night here at the jersey shore we were all in the 20's and Atlantic city int airport set a record low of 29 degrees. wish I could just even see flurries I'm so snow deprived lol.

[NYCSuburbs]

This came nothing even close to what the NAM had early yesterday... the CMC was the closest by showing a very weak, partially broken apart system quickly moving through the region. Who would've known that even the CMC would perform better than the NAM

[grandpaboy]

This came nothing even close to what the NAM had early yesterday... the CMC was the closest by showing a very weak, partially broken apart system quickly moving through the region. Who would've known that even the CMC would perform better than the NAM

Actually the CMC has done alot better than the NAM in recent events going back to the winter......

[weathernut29]

Actually the CMC has done alot better than the NAM in recent events going back to the winter......

No modle has done good all winnter but in everyones emagination maby we will get snowwwwww

[NYCSuburbs]

No modle has done good all winnter but in everyones emagination maby we will get snowwwwww

The bolded is unfortunately true... the supposedly "king" ECM also had failures, especially the Feb 23-24 storm which it didn't handle well at all. The CMC wasn't great, and it was still better than the NAM, and the GFS as always wasn't anything close to a perfect model.

While this winter wasn't handled great by the models, it's no excuse to disregard them as useless; with the models at least we have some idea of the pattern, without them we would barely even have a single idea on the forecast beyond 3 days. Models aren't meant to be taken directly as this past winter showed, but are meant to be used as guidance to help create a forecast.

By the way, speaking of the models, they're all over the place again this week... and the Greenland block is now added into the equation to further complicate things... sounds like a week of difficult forecasting coming up.

This post has been edited by NYCSuburbs: Apr 29 2012, 09:49 PM

[NorEaster07]

Some rain coming through tonight/tomm but I dont know what to focus on right now.

The 1"+ of rain over NorthEast or the 5.40" of rain in Florida in a 24 hr period.

Latest GFS 12z


This post has been edited by NorEaster07: Apr 30 2012, 11:14 AM

[jdrenken]

Some rain coming through tonight/tomm but I dont know what to focus on right now.

The 1"+ of rain over NorthEast or the 5.40" of rain in Florida in a 24 hr period.

Latest GFS 12z

This actually needs to be placed in a new thread.