Short range model discussion - into 2018

[knocker]

The outlook remains much the same so as usual it's a matter of pinning down the regional detail.

Overnight the cold front that brought some light rain to the north west yesterday has continued to stagger south east but any precipitation has virtually died out. Never the less it has still brought cloud to the the NW, Wales and parts of the west midlands

which will linger all day but more importantly it marks the boundary between the cooler air behind it and the warm and more humid conditions further south where it will be sunny and very warm again today

The cloud may linger in some places but generally a clear night for most but very warm in the south east again. So Wednesday will be sunny and warm with the odd shower in the north west but later in the day a chance of some storms in the south east, particularly East Anglia

But as can be seen changes are afoot to the west and by 00 Thursday the quite intense upper low is getting organized and putting some pressure on the block.

On the surface this equates to wave depressions running around the main surface low with the associated surface front(s) pushing east across Ireland whilst at the same time advecting warmer air from the south resulting in a very warm/hot day on Thursday with light rain attempting to push in from the west.

During Friday the fronts will gain some traction and slowly traverse the country which will initiate a W/E split with the latter remaining very warm but also an increasing risk of storms

By Saturday partly cloudy and cooler in much of the country but still quite warm in East Anglia,

Thus at T120 the NH profile is thus

[knocker]

The ecm is essentially the same for the end of the week

[knocker]

The 0600 UTC geostationary

[knocker]

Just musing off piste this morning, as one does from time to time, about another hot spell later next week. If the EPS is anything to go by the thinking appears to be of a week trough in mid Atlantic but in particular a readjustment of the alignment of the block to the east as it slips south and becomes more SE orientated (and eventually weaker). This could facilitate WAA from the same direction and include the UK on the western flank

[knocker]

The 0900 UTC geostationary

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High res. MODIS at 12 UTC and chart

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This evening's ICON would appear to agree with morning's fax charts

[knocker]

The troughs from the west disrupting the plume and creating the storm potential

[knocker]

The Friday fax and the ecm

 

[knocker]

With reference to an earlier off piste post the key elements for another brief hot spell remain the Atlantic trough disrupting and the high cell over Morocco ridging north east. What could go wrong?

 

[knocker]

Again no great change in he outlook. Warm over the next couple of days generally and hot in the south east before a transition to cooler weather over the weekend with even some rain.

Today starts off pretty clear, although quite muggy in some areas, although there is cloud over N. Ireland and Scotland

which may linger whilst elsewhere it will be sunny and rapidly becoming very warm, particularly in the south east. The heat may well generate the odd shower in some regions , particularly the NE and E. By evening the upper trough to the west is busy adjusting it's position and the surface wave and associated front will track north just to the west of Ireland and cloud and some rain may just impinge on the west of Scotland.

The adjustment of the upper low to the west facilitates the advection of even warmer air that will impact some areas on Thursday, particularly the south east,whilst Scotland and western areas remain much cooler. The odd storm may be triggered in the north east.

Friday sees the start of the transition with the low to the west taking closer order and associated fronts starting to push across the country from the west. With very warm air still being drawn up from the south this not only creates a sharp temp divide but also the ideal environment for some storms as the cooler air mixes with the plume. Thus the likelihood storms in north eastern and eastern regions.

By Saturday the fronts are through the UK and a much cooler regime, with some showers, pertains as the trough to the west goes through a contortionist phrase as the associated energy hits the still very impressive block to the east.

By Sunday the next wave is swinging up from the south west with the associated front thus cloud and rain will impinge the west and along with that, probably the coolest day many will have experienced for a while

The NH profile at T120

Just to note the position of the wave and fronts on Sunday is still in question thus the discrepancy between the gfs and fax,

Edited July 25, 2018 by knocker

[knocker]

9 hours ago, knocker said:

With reference to an earlier off piste post the key elements for another brief hot spell remain the Atlantic trough disrupting and the high cell over Morocco ridging north east. What could go wrong?

 

And apropos the above

[knocker]

This morning's fax charts for Friday and the ecm

The 0600 UTC geostationary

Edited July 25, 2018 by knocker

[knocker]

The Icon for Friday

Certainly conducive to a storm or two

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The high res. MODIS at 1100 UTC

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The high res.MODIS at 1245 UTC and the 1300 chart

Edited July 25, 2018 by knocker

[knocker]

Convective overview from the Icon

[knocker]

Another wave depression forms in the baroclinic zone near Newfoundland at T36

And runs quickly east on the combined jets

Before swinging north over Ireland as the front(s) traverse the country Sunday/Monday bringing rain and more wind than we have had of late

 

Edited July 25, 2018 by knocker

[knocker]

The 1500 UTC Synops

http://www.met.reading.ac.uk/~brugge/15.html

[knocker]

This evening's fax charts and the ecm

 

[knocker]

And just to qualify something about lapse rates. They are measured and quoted as c/km

Thus the Dry Adiabatic Lapse Rate is 9.8C/km

The Saturated around 5.0C/km

And the environmental normally taken as 6.5C/Km

The figure often bandied around to calculate the surface temp from the 850mb temp in optimum conditions varies between 15C-18C (taking into account surface heating and warm night time temps) and this comes about by simply taking the 850mb geopotential height and the DALR.and doing the simple calculation. But the result is not the lapse rate and it might be confusing when consulting lapse rate charts such as this.

And as can be seen the calculation can be done between any pressure levels.

Edited July 25, 2018 by knocker

[knocker]

As I've no doubt everyone is aware quite a complicated picture over the next couple of days, much of which will be real time observing, before a more mundane period sets in so this will merely be a simplistic outline.

It's been a pretty clear night for most

But for all that temps have remained high in many areas, still hovering around the 20C mark in the south. This sets the tone for the rest of the day which will be generally sunny and very warm, particularly in the south east where it will be hot. Cloud will bubble up and a few isolated storms could be generated in the east/north east. Out to the west the wave depression is tracking rapidly north and the associated front is over Ireland so cloud and patchy rain may impinge on N. Ireland and western Scotland later.

Overnight Thursday the aforementioned cold front moves slowly east and the general movement of the system to the west drags even warmer air up from the south thus eastern and south eastern regions could well be hotter than today. But this is complicated by storms also tracking north east and later the cooler air from the cold front entering the mix thus all the ingredients for some nasty storms developing in eastern areas with possibly, hail, lightening and localized intense rainfall if you catch one. The storms. cloud, etc is a complicating factor vis the max temp

By Saturday the cold front is in the North Sea with a complex area of low pressure to the NW/N thus a much cooler day for everyone albeit still some storms and showers around.

Sunday sees the next wave depression and associated fronts arriving from the south west so a generally cloudy, rainy day, with strengthening winds and certainly much cooler than of late.

The rain will generally clear by Monday except for N. Ireland and Scotland which may well still experience some heavy rain and quite strong winds

The NH profile at T120

 

Edited July 26, 2018 by knocker

[knocker]

This morning's 0500 chart

and some further thoughts on Friday

[knocker]

At T48,72 the second wave is on it's way

portending a wet an quite windy day on Sunday

Edited July 26, 2018 by knocker

[knocker]

The high res MODIS at 1140 UTC (courtesy DSRS) and the 1100 chart