Jump to content
Paul

Mid-winter - models, teleconnections and nowcasting

Recommended Posts

Not surprisingly the gfs det run fits neatly into the framework of the medium term GEFS mean anomaly this evening. The salient points being high amplification upstream; and a very strong westerly flow across  the Atlantic to the quite intense vortex lobe/trough aligned south over the UK which facilitates a secondary  energy flow from around the Iceland area. Thus portending very unsettled with temps varying around the average but with the usual caveats of large day to day swings and regional variations  as systems track east and different energy flows come into play

gfs-ensemble-all-avg-nhemi-z500_anom_5day-6411200.thumb.png.358f9d903252fa5436b06ab4a6f44507.png

No significant difference in the ext period, perhaps some lessening of the intensity but that's to be expected

gfs-ensemble-all-avg-nhemi-z500_anom_5day-6778400.thumb.png.bb7d1034e009038b6a1ad9a905b3f11b.pnggfs-ensemble-all-avg-nhemi-t850_anom_5day-6778400.thumb.png.f9064b195dde9422b253065c16b00536.pnggfs-ensemble-all-avg-eur-t2m_c_anom_5day-6778400.thumb.png.eacb3b865ad67c2539cd52eb1f49f1b7.png

 

Edited by knocker

Share this post


Link to post
Share on other sites

There is not much to say about the ext EPS that has not been said already, so apart from a reminder of the usual caveats, the charts should suffice

ecmwf-ensemble-avg-nhemi-z500_anom_5day-6756800.thumb.png.efc5f04c0a0b11c0e555452398cc236c.pngecmwf-ensemble-avg-nhemi-t850_anom_5day-6756800.thumb.png.01fadd68e95ecd416972d9a4125a8a93.pngecmwf-ensemble-avg-eur-t2m_c_anom_5day-6756800.thumb.png.bf7f95bd09456114e423797d486db554.png

Share this post


Link to post
Share on other sites

A quick glance at the EC weeklies update for the first two weeks of January

Jan 01-08

Salient points

TPV over northern Canada adjacent to the Alaskan ridge

Strong westerly upper flow exiting the eastern seaboard south of the trough in the  NW Atlantic

But this abates and backs a tad in the east courtesy of some ridging from the positively anomalous subtropical high and low pressure in the eastern Mediterranean

This would portend a relatively quiet and dry spell of weather but tending towards a NW/SE split with temps around average

ecmwf-weeklies-avg-nhemi-z500_anom_7day-8441600.thumb.png.51aa3489e8c27bc092742d6a7923f517.pngecmwf-weeklies-avg-eur-t2m_c_anom_7day-8441600.thumb.png.6d97c3a46c5c8e0edd9811cacaa1f536.pngecmwf-weeklies-avg-eur-precip_168hr_inch-8441600.thumb.png.5c4a665e9eedca8f26c52a3dcc992121.png

Jan 08 - 15

No significant changes except perhaps some stronger ridging over Scandinavia

ecmwf-weeklies-avg-nhemi-z500_anom_7day-9046400.thumb.png.dd0b7b752627ff0abc0f5c5888c687ce.pngecmwf-weeklies-avg-eur-t2m_c_anom_7day-9046400.thumb.png.93806056f3b0a955d98f03ea4f46d8a6.pngecmwf-weeklies-avg-eur-precip_168hr_inch-9046400.thumb.png.445831aef5ab7e402d73afd7278eee5e.png

I feel a ditty from Max Bygraves coming on

 

Edited by knocker

Share this post


Link to post
Share on other sites

Outlook - unsettled and very windy at times

The North Atlantic 300mb wind field and surface analysis for midnight

gfs-deterministic-natl_wide-z300_speed-5590400.thumb.png.397144f87de03192eece5cfe728d4d05.pngPPVA89.thumb.gif.f400261e8dc645153520a6d547aa60ba.gif

Today will be windy with bands of rain and showers traversing the country associated with various fronts/troughs eventually clearing the south east by 1800, Clearer weather behind bur showers in the north west. Temps higher than of late but perhaps some colder air creeping into the north of Scotland behind the occlusion

PPVE89.thumb.gif.b2c9934edffc47dd65de0e89bcd8ae89.gif2mtemp_d02_20.thumb.png.b9a22db11e149be3c2bca1ab12a85d7e.pngmeanreflec_d02_24.thumb.png.4dcd0ab4eabf582ceaa2115421ceccf5.png

A relatively dry night and frost free with the winds abating but showers continuing in the north courtesy of the occlusion

PPVG89.thumb.gif.6355e20761d6fb42153581b7a062aedd.gif

Not a bad day on Saturday thanks to weak and very transient ridge but out in the Atlantic some active cyclogenisis has been taking place and the fronts associated with the deep low will bring rain and strengthening winds to N. Ireland and western Scotland by late morning with the heavier stuff arriving by 1800 which will track south east through saturday night

PPVI89.thumb.gif.81a317e27fcd0ae7f17b381448d3273a.gif2mtemp_d02_44.thumb.png.5b645d568ebf979f2d350dce496af64e.pngprecip_d02_48.thumb.png.710045151b1f2019d88cf97dd373dc5d.png

The rain soon clears but over Saturday night and though Sunday there is a lot going on, including some rapid cyclogenisis, as the trough re-orientates over the UK resulting in a very windy day with severe gales around some coastal areas with frequent heavy showers and longer periods of rain

gfs-deterministic-natl_wide-z300_speed-5806400.thumb.png.fa8f5f9ec365a55ab04e31324112913a.pngPPVJ89.thumb.gif.a58f399bf14e2d41e687971b67cfbbba.gifPPVK89.thumb.gif.29e37b2ea2f5f5182253f2692521aedd.gif

gfs-deterministic-uk-precip_6hr_inch-5828000.thumb.png.a5dc64de970242a1bba22ad82943fe90.pnggfs-deterministic-uk-t2m_c_max6-5828000.thumb.png.7558b8b9cbf6d9fafb4abf6aa30dfba9.png

The whole caboodle moves east on Monday resulting in the surface wind veering northerly, introducing colder air, and remaining quite strong down the east coast accompanied by showers

PPVM89.thumb.gif.e20a319cf2f283d2b79b434807107031.gifgfs-deterministic-uk-t2m_c_max6-5828000.thumb.png.7558b8b9cbf6d9fafb4abf6aa30dfba9.png

But in the baroclinic zone to the west more rapid cyclogenisis is taking place and the fronts associated with the deep low over Iceland sweep across the country on Tuesday bringing heavy rain and strong winds

gfs-deterministic-natl_wide-z300_speed-5979200.thumb.png.9c1264a06e8daee4ecf9de54c3042ab9.pnggfs-deterministic-natl_wide-t850_anom_stream-5979200.thumb.png.832ae16cac59f34851887bc80bc1ac59.pngPPVO89.thumb.gif.881c41981185b52eef41c50f6f1de676.gif

gfs-deterministic-uk-precip_6hr_inch-6000800.thumb.png.42b29a9b456805a75932efb33a273a15.pnggfs-deterministic-uk-t2m_c_max6-6000800.thumb.png.f46186e730f03392ec6a692dbf42160c.png

 

Edited by knocker

Share this post


Link to post
Share on other sites

According to the gfs over the net couple of days the upstream amplification boosts the jet and the unsettled theme continues

gfs-deterministic-nhemi-z300_speed-6022400.thumb.png.37823982ce0262dfe6558abe04d172c8.pnggfs-deterministic-nhemi-z300_speed-6195200.thumb.png.6fe79776b2ae5d3e3741d8462bc035e0.png138.thumb.png.dd020badeb1898f0c4459694019cca43.png162.thumb.png.698488e05d208b9554c21fa3502cbd9b.png186.thumb.png.ed198a54f0351ae8f67bc1997268e550.png

Share this post


Link to post
Share on other sites

The ecm very unsettled over the last half of the run so it's basically a matter of sorting the detail

ecmwf-deterministic-nhemi-z500_anom_5day-6454400.thumb.png.95a0515e6e584dc8be6cfea2d60cd46d.pngecmwf-deterministic-nhemi-z300_speed-6260000.thumb.png.57251380ee3cad2b1f4ce488f90a46ff.png

144.thumb.png.3f54b6383403bb64e2d97ac9ec82fc5c.png168.thumb.png.2be3f113bfa1c1ea1a0185346add685a.png192.thumb.png.217988f87a3ee4c0abf22984ebbf1961.png

Share this post


Link to post
Share on other sites

The salient points of the ext EPS mean anomaly this morning

Alaskan ridge extending into the Arctic towards the amplifying subtropical zone in eastern Europe

The tpv northern Canada loosely extended across Greenland to the trough over the UK

Strong westerly upper flow across the Atlantic

Ergo continuing unsettled with temps a tad below average, particularly in the north. This probably reflects the usual caveats vis the day to day variations and in particular the ingress of colder air from the NW/N

ecmwf-ensemble-avg-nhemi-z500_anom_5day-6800000.thumb.png.e0ecbb12f42383ad084303d6114cb862.pngecmwf-ensemble-avg-nhemi-t850_anom_5day-6800000.thumb.png.85fe41c30f42cd465a39c7bdd7b03418.pngecmwf-ensemble-avg-eur-t2m_c_anom_5day-6800000.thumb.png.25d2539052c4425c983a34c8239c69ed.png

 

Share this post


Link to post
Share on other sites

An impressive, sharp gradient cold front being shown by the UKV on Tuesday. Could be some wintriness on its trailing edge, and squalliness along the convergence line. If it plays out as forecast of course.

cf2.png cf1.png

cf4.png cf3.png

 

Share this post


Link to post
Share on other sites

The 2 xT240hrs mean anomalies 500 hPa NH charts and the days 6-10 mean 850 hPa anomalies for Europe.

gfs-ens_z500aNorm_nhem_41.thumb.png.69b8211bc2311acb4fbd97c2205a2146.pnggfs-ens_T850aMean_eu_6.thumb.png.2bfdd7b46e2cf00587a92efe75e81acd.png

 

ecmwf-ens_z500aNorm_nhem_11.thumb.png.501778d07d1ec2df99d6422dfe0b0245.pngecmwf-ens_T850aMean_eu_6.thumb.png.d64bcf3656917ccacfbc64da1b0cbe1e.png

Pretty similar maybe  GFS a little flatter out west but  the overall picture of a rather cold west to north west pattern into week 2.

 

 

Share this post


Link to post
Share on other sites

The 0600 ecm not looking great for the south west and west wales Sunday night/Monday morning

ecmwf-deterministic-uk-gust_kt-5842400.thumb.png.db6799f015f9c0585462c0c2ddd4e342.pngecmwf-deterministic-uk-gust_kt-5860400.thumb.png.e1c7e7385333c5e238c09b1b2b76a9bf.pngecmwf-deterministic-uk-gust_kt-5871200.thumb.png.1c49464743a8e69584ed137da0ec4b69.png

 

Edited by knocker

Share this post


Link to post
Share on other sites

The latest fax's show the tightening of the isobars as the gales hit Sunday/Monday with more lows queueing up in the Atlantic.


fax72s.thumb.gif.d87e4b86b149f33202d0dd18ffe0a1fa.giffax84s.thumb.gif.cd667781569f7962b42f190c918e15df.gif

The Atlantic +nao Winter pattern in all it's glory.

Share this post


Link to post
Share on other sites

As has been mentioned previously upstream amplification and vortex displacement pumps up the jet five days hence

gfs-deterministic-nhemi-z500_anom-6065600.thumb.png.df32364d9f646abea13eb6f39d3c001d.pnggfs-deterministic-nhemi-z300_speed-6065600.thumb.png.5b8c6b9f08d0684e27708371d816e7f1.png

Resulting in a very mobile Atlantic over the last half of next week

gfs-deterministic-natl_wide-z300_speed-6195200.thumb.png.624d71b2aa4969123e63e0b7673cc348.png144.thumb.png.c9fa8fa3e7cea9fd9d027ac8df9f2781.png168.thumb.png.2e9131715528d24f66e1e61b2da5aaf3.png

192.thumb.png.469d99d6ff62f0e0b8f3ce153d6cb046.png

Share this post


Link to post
Share on other sites

Next Tuesday too as mentioned earlier is still looking interesting as polar air cuts in from the west especially later in the day.

w1.thumb.png.cde42bf2f53d24cdf6aa2ce3c9cbc0ef.png850.thumb.png.7c4b200c2fb942b4ebe15f6d8d48c7ce.pngp1.thumb.png.d943e5b9c2294b6fa8113467c717b744.png

An active cold front with notable wind sheer and a sharp thermal boundary.

A large drop in 850,s with strong winds and gusts to gale force in places.heavy squally rain as the front comes through turning wintry over higher parts of Scotland. 

Share this post


Link to post
Share on other sites

Possibly the most striking feature of the ext GEFS mean anomaly is the strength of the east European ridge which compliments the upstream amplification which has the Canadian vortex extending around  some weak ridging into eastern Greenland to the trough which is now over Scandinavia, adjacent to the aforementioned ridge Thus still a strong westerly upper flow across the atlantic portending unsettled with temps a tad below average but with the usual caveats that there is likely to be fair range in the day to day detail with the variation of the energy flows

gfs-ensemble-all-avg-nhemi-z500_anom_5day-6843200.thumb.png.651ad03c8bd3a700c4e3e91f83d2c57f.pnggfs-ensemble-all-avg-nhemi-t850_anom_5day-6843200.thumb.png.8a5e92c06e941df228df547db9e61c17.pnggfs-ensemble-all-avg-eur-t2m_c_anom_5day-6843200.thumb.png.38f5dfe33d53ae990ed1285c7d770740.png

Edited by knocker

Share this post


Link to post
Share on other sites

Looking at the EPS 5-10 mean anomaly this evening one certainly wouldn't rule out some wintry incursions within the day to day variations with the secondary lobe north of the UK and the quite intense trough aligned south of it

ecmwf-ensemble-avg-nhemi-z500_anom_5day-6497600.thumb.png.0036f16164399bdeb0489d35ca3430d3.png

And the ext is pretty much as before so the charts should suffice

ecmwf-ensemble-avg-nhemi-z500_anom_5day-6843200.thumb.png.69fe18975f7c990ee12d214ee59258b3.pngecmwf-ensemble-avg-nhemi-t850_anom_5day-6843200.thumb.png.1d7cd6d077633f71706eb3ffd6483060.pngecmwf-ensemble-avg-eur-t2m_c_anom_5day-6843200.thumb.png.ec603387e217254d815bcea37e27f363.png

Share this post


Link to post
Share on other sites

Outlook - unsettled and very windy at times

The North Atlantic 300mb wind field and surface analysis for midnight

gfs-deterministic-natl_wide-z300_speed-5676800.thumb.png.8e182e29f02a0ae6f45f158fa9e77a1e.pngPPVA89.thumb.gif.1bdb76436a06e581c00be23d5b56dcfb.gif

Essentially today is the calm before the storm with broken cloud and the odd sunny interval, courtesy of a very transient ridge. But fronts associated with the developing area of low pressure to the north west will quickly bring rain into western Scotland by mid morning, accompanied by strengthening winds, which will spread east through the rest of the day

PPVE89.thumb.gif.1790ab0f535a4b9e8c7ea3a874faba6e.gif2mtemp_d02_20.thumb.png.80c3ef310d3327d0fe6a86ec0eb9f00b.pngprecip_d02_22.thumb.png.c07d2cf41d5d3449bab470c9deaf9cb7.png

The warm front clears to the east this evening but the time spent in the  windy warm sector is brief as the cold front and a band of heavy rain sweep east through the night with heavy showers following on behind in the very strong winds which could reach gale force in coastal regions

PPVG89.thumb.gif.8e16f095b2e4f7985e103d957d4681c5.gifprecip_d02_29.thumb.png.46c3724cc6b759f59c2df9fb14c17154.pngprecip_d02_33.thumb.png.e0df666b331dd7a510f898aff8ea0479.png

The rain quickly clears Sunday morning leaving a day of squally heavy showers, mainly concentrated in western regions, which could well have hail and thunder in the mix. But the complex trough is still developing to the west of Ireland

gfs-deterministic-natl_wide-z300_speed-5828000.thumb.png.be69c2e901aea402d3a14feb81dc2bb8.pngPPVI89.thumb.gif.d35e8c4ee13eb6377003a8ce2c06b9ec.gif2mtemp_d02_44.thumb.png.e575348d99a5b2155a16c61b11829e0b.png

Over Sunday night and though Monday the upper trough re-orientates and moves east and in the process very strong winds will initially effect western and south west regions and then eastern coastal regions as the surface wind veers northerly

gfs-deterministic-natl_wide-vort500_z500-5892800.thumb.png.c7a3089e39d5ea4920d2aa38e270a720.pngPPVJ89.thumb.gif.9b087f80564ab96607c2bb976d41ee40.gifPPVK89.thumb.gif.b70820a8419d6862cb8ddfaecc902ccc.gif

gfs-deterministic-uk-gust_swath_kmh-5849600.thumb.png.e6d4acddc0154e0ec228edfb61370263.pnggfs-deterministic-uk-gust_swath_kmh-5892800.thumb.png.488db2c3c4bb1291454ed87d6928207d.pnggfs-deterministic-uk-t2m_c_max6-5914400.thumb.png.eee25a8a2a4d3857177767f1f6a8e3dd.png

There is little respite from the windy and wet weather as by Tuesday further rapid cyclogenisis has taken place out in the Atlantic near the left exit of the jet and the associated fronts sweep across the country accompanied by heavy rain and strong winds

gfs-deterministic-natl_wide-z300_speed-5979200.thumb.png.45a1d4ebb23225727e273aa760766003.pngPPVM89.thumb.gif.d9f5d865f935785cb332a0707f3f558d.gifgfs-deterministic-uk-t2m_c_max6-6000800.thumb.png.6d49840c6f0a6c8151555edb0987195a.png

The fronts clear away by Wednesday leaving the UK in the circulation of the very deep low of 943mb east of Iceland. Thus a day of squally showers, with thunder and hail in the mix, which may well coalesce in the south courtesy of the trough swinging around within the circulation

PPVO89.thumb.gif.94645c0f3212f08f837caedb95f159bc.gifgfs-deterministic-uk-t2m_c_max6-6087200.thumb.png.197cfde9f6b2a01e0601f3c1208ee673.png

 

Edited by knocker

Share this post


Link to post
Share on other sites

The upstream amplification and the pumping up of the jet has been discussed in previous posts so suffice it to say a very mobile Atlantic for the rest of the week and continuing very unsettled, according to the gfs

gfs-deterministic-nhemi-z300_speed-6238400.thumb.png.3bd578d5823db6a408ab2660f5d0b665.png132.thumb.png.70ef9c306ca2bca2e6f942fcd5169110.png156.thumb.png.44b48b3e1f0b9ae7cd09bde65070fbbc.png180.thumb.png.1e2ead090cf0f3d3aa84cf37c0a8aa3f.png

Share this post


Link to post
Share on other sites

The key factor with the ext GEFS this morning is the possibility of the retrogression of the European trough and some signs that the subtropical high is stirring. This shouldn't be a complete surprise as the latest EC weeklies was indicating something similar

gfs-ensemble-all-avg-nhemi-z500_anom_5day-6972800.thumb.png.25044ae98703aa665ff8e1b9ab582f64.pnggfs-ensemble-all-avg-nhemi-z500_anom-6972800.thumb.png.713696174f566838fec7e2efb774c9d1.png

Share this post


Link to post
Share on other sites

The ecm also unsettled for the latter half of the run and the mobile Atlantic could well include some wintry incursions

ecmwf-deterministic-nhemi-z500_anom_5day-6540800.thumb.png.a1ad35bb335c201d4208b85dcf680f52.pngecmwf-deterministic-nhemi-z300_speed-6346400.thumb.png.acad63f130430b3020fcffdcc7ec0bfb.pngecmwf-deterministic-eur-t2m_c_anom_5day-6540800.thumb.png.d52d3331a9dfa34d4100ebbf127f1eef.png

132.thumb.png.f77370ba29a0a5514286abff1397523a.png156.thumb.png.e7082e3d010204461b0323cba4848658.png198.thumb.png.c5a9345e3d6a3dd2af32be77325b0a2a.png

Share this post


Link to post
Share on other sites
4 hours ago, knocker said:

The fronts clear away by Wednesday leaving the UK in the circulation of the very deep low of 943mb east of Iceland. Thus a day of squally showers, with thunder and hail in the mix, which may well coalesce in the south courtesy of the trough swinging around within the circulation

PPVO89.thumb.gif.94645c0f3212f08f837caedb95f159bc.gifgfs-deterministic-uk-t2m_c_max6-6087200.thumb.png.197cfde9f6b2a01e0601f3c1208ee673.png

 

note the 528 dam line across northern areas... snow showers?

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...