Short range model discussion - into 2018

[knocker]

A quick overview.

After the dismal (for many areas) period of low pressure influence a major pattern change is now under way. Over the limited period of this thread this essentially involves a blocking high to the east and trough dominated Atlantic boosted by a vortex fragment/lobe dropping south east from Canada to become a major feature in mid Atlantic and then the whole caboodle sustaining some amplification. As ever with this sort of scenarion the precise orientation of the major features are critical when it comes to detail.

Anyway enough waffle. Today at the start of the transition the UK finds itself in a weak ridge so a mainly fine day with sunny intervals and light winds and temps much warmer than of late. By late this evening a front and some rain will be approaching Cornwall.

By 1200 Sunday the depression associated with the above mentioned front is 983mb west of Ireland and the front and patchy rain is moving east across the UK. with temps in the freshening south westerly wind above average, particularly in the east and Scotland. At the same time the major upper low/lobe has made an entrance in the western Atlantic.

But by 1200 Monday the aforementioned amplification is under way with intensification of the Bermuda and European ridges which flank the now nearly stationary intense upper low in mid Atlantic. Similarly the large surface feature and so the front and patchy rain tend to fizzle out over the UK leaving north west Scotland in the firing line of the fresh south westerly and any rain, Temps still a little above average.

Tuesday sees the battle between the two forces west/east reach a peak as the European high intensifies further, the trough is forcibly restructured and the UK becomes the filling in the sandwich between the two as the south westerly wind freshens further. and again any frontal activity and rain is confined to the north west Temps still a little above average in the east.

Last evening's fax chart for 12 Tuesday but look away now if you are of a nervous disposition.

By 1200 wednesdat the high cell has become established over northern Germany, and with the trough to the west now neutrally orientated, is the major influence vis the UK weather so a dry and warm day (temps well above average) for all areas.

Edited April 14, 2018 by knocker

[knocker]

Satellite at 0430, Olez!

[knocker]

Sunrise with the geostationary (courtesy DSRS) and interesting cloud over the Mediterranean associated with the low there.

[knocker]

The high res. MODIS at 1150 UTC and the 1200 chart

 

[knocker]

The occlusion and patchy rain will arrive Cornwall late this evening and cross the country overnight and through tomorrow, Staying dry and pleasantly warm in the East and Scotland.

 

 

Edited April 14, 2018 by knocker

[knocker]

Interesting1500 geostationary )courtesy DSRS) showing the low and fronts to the west and what I think is Stratus n the Channel. I say this as Stratus has encroached here in the last couple of hours from the south

 

 

Edited April 14, 2018 by knocker

[knocker]

Becoming increasingly windy and wet, although the latter confined to western regions, through Monday evening and Tuesday morning as the frontal system associated with the deep low to the west of Ireland tracks NE.

[knocker]

The 1800 geostationary. Cirrus and high Ac arrived here about an hour ago

[knocker]

The front and patchy rain associated with the depression south west of Ireland are currently over the south west of England and Wales. These will track north west during the day leaving brighter and showery conditions behind the front and quite windy in the west. Pleasantly warm in areas that escape the cloud and rain such as north east Scotland.

Some more organizes showery activity will track north overnight but by 1200 tomorrow it will have cleared as the low to the west has been absorbed by the large and deep low in mid Atlantic, all courtesy of the intense upper low that been discussed previously. All this leaves the UK with a mainly dry south westerly airstream with temps shading above average.

But fronts and rain associated with the low are tracking slowly north east and by 00 Tuesday are already impacting N. Ireland and Scotland and during the day the rain will slowly progress south east but tending to fizzle out as it hits the block of the Azores high pressure that has become more amplified and is ridging north east between the restructuring Atlantic trough and the low in the Mediterranean. All of which massively redirects the very strong jet. So essentially this boils down to some wet and windy weather in the northwest, drier and sunnier in the south east and this is reflected in the temps.

So by midday Wednesday the burgeoning Azores has phased with the European ridge and established a high cell over Germany and realigned the upper trough in the west to neutral and in the resulting SSW flow initiated some quite intense WAA. Thus a warm day for the UK with plenty of sunshine

By 1200 Thursday it's all getting a bit messy with the block to the east intensifying, the trough to the west deconstructing with a very strong jet running around it and little lateral movement. Resulting in the UK once again being in a col, but on the plus side another sunny and very warm day.

Edited April 15, 2018 by knocker

[knocker]

Satellite at 0600 UTC and surface chart

[knocker]

The ecm not dissimilar to the GFS in this time frame with the middle and end of the week being very warm but the analysis is really quite fragile and with still, it would appear. a fair amount of energy upstream, the further evolution is a long way from being definitive

[knocker]

The EPS 6-10 mean anomaly may clarify my slightly vague comment above,

Quite an intense vortex lobe N. Canada with associated trough orientated SE through Greenland and a ridge NE North America Thus two energy flows, one tracking south east passed southern Greenland and the other exiting the eastern seaboard resulting in a strong westerly upper flow across the Atlantic and over the UK with the block weakening to the east and which also tends to suppress any ridging from the Azores,

The detailed surface analysis by the det will sort the likely interaction between the trough and the high pressure to the south and systems tracking east

 

 

[johnholmes]

This is my notes on my anomaly file this morning 

Sunday 15 april

 http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

 

 http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Ec-gfs some changes from above (charts copied on Thursday), neither have such a marked ridge indeed ec has none, and does suggest fairly unsettled weather would be likely if it is correct

Noaa keeps more ridging thus a settled pattern remains if it is nearer what transpires

2 for one pattern and one for another?

Usually noaa is closer to the upper air actual over the period-as ver time will tell.

The 8-14 NOAA shows a flattish not overly strong atalntic flow  into a trough just west of the UK.

 

[knocker]

The 1200 geostationary shows the swathe of cloud associated with the occlusion tracking north east

But also the filling low west of Ireland that is about to be absorbed by the main feature, the western edge of which can just be seen.

 

 

[knocker]

Overnight after the occlusion has cleared showers will be the order of the day with some more concentrated in the north west before morning before a generally dry day in the brisk south west wind. But by evening the frontal rain associated with the deep depression in mid Atlantic has encroached over Ireland and western Scotland. Temps around average.

[knocker]

The setting sun highlights the massive low in the Atlantic on the 1800 UTC geostationary

[knocker]

Patchy rain in Scotland and the north of England will dissipate quickly this morning from the north west leaving the UK with a dry day with sunny periods and light winds  Note at midnight the major Atlantic depression is down to 943mb.

But by 1800 the low and associated fronts have slowly moved east and rain and strengthening winds are into N. Ireland and western Scotland. During the night this rain, heavy at times, and strong winds will track south east to include northern England and Wales but during the morning it will tend to fizzle out at it reaches the Midlands. Thus the south and east will remain dry and relatively clear.

So by 1800 on Tuesday the Atlantic is dominated by a large and complex low pressure area coming up against a strengthening block to the E/SE as the Azores and European ridges amplify leaving the UK in a strong south westerly with temps above average.

Overnight Tuesday the high pressure to the east continues to intensify and become more influential over the UK as it forms a high cell over Germany and spreads west whilst at the same time putting the upper trough to the west under pressure and this becomes more neutrally tilted.Thus a warm, dry day with plenty of sunshine and temps way above average.

A not dissimilar picture on Thursday but the High pressure to the east ha become positively tilted and the trough to west has started to deconstruct under pressure from the twin upstream energy flows, in particular the strong jet leaving the south east seaboard. Thus the surface ridge over the UK comes under some pressure and resulting a freshening south westerly wind over north west Scotland  But still dry and very warm day, even hot in the south east, with the temps way above average.

By 1200 Friday the energy continues to exert pressure and the trough duly deconstructs with a cut off low popping south east towards Marrakesh with the ridge over the UK now tenuously supported by the Azores ridging north east from a long way to the south west. This results in the UK remaining dry and sunny with light winds and with temps still way above average, hot in places,with the exception still being north west Scotland that remains in a fresh southwesterly and patchy rain.

Later on Friday perhaps a risk of some thundery activity drifting north from the continent. All of this is according to the GFS

 

 

 

 

Edited April 16, 2018 by knocker

[knocker]

Satellite 0550 UTC

[knocker]

The 0600 geostationary (courtesy Dundee Satellite Receiving Station) highlighting the cloud associated with the shallow low and inclement weather in the area of the Pyrenees 

[knocker]

The 0900 geostationary (courtesy DSRS) and 0600 Atlantic and 0900 UK charts.

[chrisbell-nottheweatherman]

First plume of the year possible later on Friday?

[knocker]

1 hour ago, chrisbell-nottheweatherman said:

First plume of the year possible later on Friday?

Rather depending how one defines a 'plume' perhaps rather more on Thursday

[knocker]

Nice 1115 UTC high res MODID (courtesy DSRS) and midday chart. Partially cloudy and widespread 14-15C

[knocker]

The rain from the front associated with the deep depression to west will reach the north west by early this evening. But it will become more concentrated and heavier overnight and tomorrow morning as the front tracks south east and eventually fizzling out during the afternoon as it struggles against the block to the south east. The squeeze caused by the aforementioned block results in a strong south westerly wind, perhaps touching gale force in the north west but in the south east, which will be free of the cloud and rain, some quite respectable temps.

 

Edited April 16, 2018 by knocker

[knocker]

The 1500 UTC geostationary