Medium/Long Range thread

[easternsnowman]

 

Generally, but its also harder to get larger departures over longer periods given natural fluctuations.

 

I think the "normal" PHL summer average temperature is about 76.  Here are all the summers which averaged 77 or more:

  1    79.6    2010  2    78.6    1995  3    78.3    1994  4    78.2    1993  5    78.0    2012,  2011  7    77.9    1991  8    77.8    2005  9    77.7    2002 10    77.2    1999,  1900 12    77.1    1988,  1973

It looks like 12 of the last 25 summers have been quite warm, so saying 1-3 above average seems normal.

[Isotherm]

Interesting that none of the composites show warmth east of the Appalachians. I wonder if something else (ENSO? MJO? SSTAs?) modulates Mid-Atlantic weather in during this period.

 

 

Looks like we might be dealing w/ a persistent Newfoundland sfc high in the medium range as we enter May. While H5 anomalies look warm on the proggs for the Northeast, a sfc high in SE Canada is backdoor city for PHL northeastward. Probably going to have many more dreary days in early May.

 

Interested to see if temps overperform the next several days. Generally looks near avg w/ mid/upper 60s through 4/30.

[NJwinter23]

Get ready for the neverending CAD/marine layer

[Quakertown needs snow]

12z gfs extended, when did we see that type of path last?

[am19psu]

Looks like we might be dealing w/ a persistent Newfoundland sfc high in the medium range as we enter May. While H5 anomalies look warm on the proggs for the Northeast, a sfc high in SE Canada is backdoor city for PHL northeastward. Probably going to have many more dreary days in early May.

 

Interested to see if temps overperform the next several days. Generally looks near avg w/ mid/upper 60s through 4/30.

Yup. My thoughts exactly.

[famartin]

Looks like we might be dealing w/ a persistent Newfoundland sfc high in the medium range as we enter May. While H5 anomalies look warm on the proggs for the Northeast, a sfc high in SE Canada is backdoor city for PHL northeastward. Probably going to have many more dreary days in early May.

:thumbsdown:

[Rainshadow]

Looks like we might be dealing w/ a persistent Newfoundland sfc high in the medium range as we enter May. While H5 anomalies look warm on the proggs for the Northeast, a sfc high in SE Canada is backdoor city for PHL northeastward. Probably going to have many more dreary days in early May.

 

Interested to see if temps overperform the next several days. Generally looks near avg w/ mid/upper 60s through 4/30.

 

As long as we steer away from that May (late 90s?) where it rained the first 12 consecutive days of the month.

[Voyager]

All I know is March sucked, April had some good moments, but is/was too cool for me. Now we have crap to look forward to for May??? Why is this spring sucking so bad???

[tombo82685]

All I know is March sucked, April had some good moments, but is/was too cool for me. Now we have crap to look forward to for May??? Why is this spring sucking so bad???

 

 

Look whats been negative since mid february..late winter/early spring -nao is pretty dominant to northeast weather.

[forkyfork]

buckets of rain?

 

[am19psu]

All I know is March sucked, April had some good moments, but is/was too cool for me. Now we have crap to look forward to for May??? Why is this spring sucking so bad???

We haven't been that far off normal, tbh. As to why it's sucked so bad, QBO/solar seems to be the culprit (look around for some of Sam's, Mike V's, and HM's posts about it), but I don't fully understand the dynamics of it.

[famartin]

All I know is March sucked, April had some good moments, but is/was too cool for me. Now we have crap to look forward to for May??? Why is this spring sucking so bad???

Your expectations for April have been too warm.  Unless you think most April's suck.  Because IPT, AVP, MDT, RDG are all 1-2 above normal for the month.

[am19psu]

Your expectations for April have been too warm.  Unless you think most April's suck.  Because IPT, AVP, MDT, RDG are all 1-2 above normal for the month.

What's the breakdown of maxs vs. mins? My hypothesis is that mins likely have warmer anomalies than maxs.

[famartin]

What's the breakdown of maxs vs. mins? My hypothesis is that mins likely have warmer anomalies than maxs.

Its fairly close to the same, a slight nod towards the mins...

AVP +0.7 max, +0.8 min

MDT +1.5 max, +0.8 min

RDG +1.7 max, +2.3 min

AVP +0.9 max, +1.0 min

[am19psu]

Thanks. Those really warm days mid-month did work

[famartin]

Thanks. Those really warm days mid-month did work

Sure did.  Here's another way to look at it...

 

Average monthly max vs. actual monthly max

IPT 83 vs. 82

MDT 84 vs. 85

RDG 86 vs. 88

AVP 81 vs. 77

 

Average number of days with highs of 70+ versus actual (Voyager will like this one a little better since they agree with his way of thinking, though note the "average" is for the entire month while the actual is obviously month-to-date):

IPT 7 vs. 5

MDT 9 vs. 7

RDG 9 vs. 7

AVP 6 vs. 5

[LMolineuxLM1]

Are we looking also at the first signs of a possible el niño building?

[Isotherm]

First 10 days of May looking more miserable by the minute. ULL over the Lakes could yield a major reversal in pcpn departures over the coming weeks. Hvy rain threat next week w/ sub tropical feed connection along the east coast. Prior to that, most of next week looks cool, damp, and nasty for early May standards.

We'll almost make it out of April with nice weather, but we go downhill rapidly by the 30th.

Signs of potentially the first 90F readings arriving in the May 12th-15th period, but that's a long ways off.

[am19psu]

First 10 days of May looking more miserable by the minute. ULL over the Lakes could yield a major reversal in pcpn departures over the coming weeks. Hvy rain threat next week w/ sub tropical feed connection along the east coast. Prior to that, most of next week looks cool, damp, and nasty for early May standards.

We'll almost make it out of April with nice weather, but we go downhill rapidly by the 30th.

Signs of potentially the first 90F readings arriving in the May 12th-15th period, but that's a long ways off.

LOL. See my avatar change

 

May 12-15 is a little earlier than I was timing it, but I was thinking around the 20th seems like a reasonable shot

[iceman56]

Some western PA snow to start the first weekend of May?

[CoastalWx]

Are we looking also at the first signs of a possible el niño building?

 

We'll have to see if any Kelvin waves try to move warmer waters east, but will be fighting a nice -PDO. Guidance seems to point towards neutral, but things can happen with predicting ENSO.

[NJwinter23]

well this pattern is a realllll fun one isnt it...who wants to tell me where the cutoff will be next week. 

[RedSky]

Pulling for the ecm in the extended as it shows the block strong enough to keep the cutoff far to our west, GFS shows a miserable pattern run after run

[Voyager]

Pulling for the ecm in the extended as it shows the block strong enough to keep the cutoff far to our west, GFS shows a miserable pattern run after run

 

You and me both. I'd like to have an extended period of NICE weather for a change.

[ptb127]

http://www.nws.noaa.gov/cgi-bin/mos/getmex.pl?sta=KAVP

 

0z MOS... they look pretty good to me.

[NaoPos]

battle brewing...

[Rainshadow]

Speaking of brewing, GFS has a 523 thickness forecast for Philadelphia on May 14th.

[ptb127]

I just looked at the 6z GFS and couldn't find a 523 thickness in Philadelphia..

 

Besides, how often has the GFS been right in that time range! 

[JamieOber]

I just looked at the 6z GFS and couldn't find a 523 thickness in Philadelphia..

 

Besides, how often has the GFS been right in that time range! 

lol...he was talking about the 0Z. Note the time when he posted that. 6Z gfs hadn't come out yet. 

[HM]

 

Last night's ECMWF has the final warming finally at 1 hpa towards 4/25 (early averaged wind at 60N). It is predicted to lead 10 hpa, which has implications on how this may manifest (there are some FW that start at 10 hpa or have no clear pattern). How the stratospheric "tornado" breaks down can help us predict the AO/NAO to some extent. There have been correlations shown for 10 hpa zonal wind and the AO/NAO relationship.

Based on what's going on with the AO/NAO now and the ECMWF stratospheric forecasts, my guess is 10hpa zonal winds go negative around 5/5-10. This means the potential for a -AO/NAO regime developing then and peaking mid-May. Depending on how that manifests, which has a lot to do with intraseasonal oscillations (current projections would lack robust Indonesian/W. PAc forcing during first half of May, possibly supporting a colder picture for us), will determine if we can put a lid on the S-C US anticyclone from hell.

 

 

The implications of this would be a "lid" on the climo "peak" of severe weather early May over the S-C Plains but possibly rapidly picking up post-peak (mid-late May). After the -AO wave peaks and relaxes/develops stronger swings and possibly an organized MJO wave through the IO-Indonesian Sector, things could peak a little later than normal (second half of May-early June).

Perhaps as we get a little closer, I'll start throwing out dates, for fun, for potential significant severe weather outbreaks. A post -AO peak in a warmer time of year and tropical forcing shifting from Atlantic to IO-Indo on the cusp of a burgeoning S-C Plains summertime anticyclone suggests this round could be a lot worse than the current period. But it is too early to say.

All of this still holds. Expecting -u winds to fully take over at 10 hpa around 5/5 or so. No crazy southern Plains anticyclone in sight and cold air dominates. Later than normal peak for "tornado season" still seems reasonable given all the players. Over in the Central Subforum, there is talk about maybe something around the 10th or so that comes ahead of something more favorable down the road. This has a lot to do with how the cutoff behaves, so low confidence.