WYorksWeather

UKV 03z from this morning going for 25C tomorrow, and 26C on Sunday. Some eastern and northern areas of England plus parts of western Scotland may scrape another warm-ish day out of it on Monday. Has to be said as well that Tuesday doesn't look horrendous temperature wise - we're not back to late April stuff here. Most areas should still be average or above with the chart below. 15z to come later for comparison.

Once again a quick update on UKV to see where we're getting to temperature wise over the next few days. First the 850hPa temperatures for the next 5 days (Fri-Tues): A warm pattern continuing through to Sunday with some areas maintaining warmth into Monday afternoon on tonight's run. By Tuesday 850s are close to average in the south but still a bit above further north. Main change from yesterday is a revert back to a stronger build of heat on Sunday, with 850s up to 10-11C in the mid afternoon. The difference between 8-9C and 10-11C will affect how high surface temperatures can climb on Sunday, along with surface conditions. Probably still too early to be absolutely certain about this. Next we can have a look at overnight lows from tomorrow morning through to Tuesday morning: Overall very high minima throughout in most areas, perhaps exceptionally so across central areas in the early hours of Saturday, Sunday and Monday. Finally, moving on to the main event - daytime maxima: In general, a trend towards gradually increasing temperatures over the next few days - absolute maxima of 24C tomorrow, 25C on Saturday, and 26C on Sunday. Always the possibility that one or two spots will go fractionally higher, so I still wouldn't rule out 27C somewhere. Beyond that it looks like eastern areas may get another warm lunchtime and afternoon before rain pushes in. Even through to Tuesday though there is nothing overly cold showing - temperatures across most areas will be near or slightly above average.

Derecho The key after low pressure takes over early next week I think will be how night-time minima hold up. ECM yesterday showed very high SSTs - I do wonder whether some of those night-time minima dropping into the mid to high single figures will actually happen. You'd tend to think that the above average SSTs might inhibit that cooling somewhat, especially if it's unsettled and therefore fairly cloudy.

Lovely day here - warm and dry. Partly cloudy at times but still a good amount of sunshine around.

*Stormforce~beka* Well - projected to be, it's still 14 days away. But as for the reason - probably an already warm Atlantic plus the extra warmth from this week probably having a delayed effect.

raz.org.rain I think the main thing will be the effect on overnight minima. Maybe a record-breaking number of tropical nights? EDIT: Forgot to add - if the pattern persists into summer itself of course - we're not going to see tropical nights in late May.

How about this for an SST pattern going into summer - valid for 23rd May from tonight's ECM. Huge positive anomalies near the UK and also positive anomalies to our south / south-west as far as the Azores.

To bring things back to model output - again my usual update on sea surface temperatures. We start with the absolute values for days 0, 5, 10 and 15. A dramatic rise in SSTs clearly visible over the next two weeks. But of course this only tells a limited story by itself in the context of seasonal changes. The anomaly maps for days 0, 5, 10 and 15 are shown below. Pretty clear to see what is going on here. The trend from a week or so ago to decrease the anomaly around day 10 (now closer to day 5) and then re-establish has been dropped. By day 15 the ECM has us in a pretty extraordinary situation. SSTs 1-2C above average near the Azores. Near the UK, SSTs are almost universally 2C or more above average, and in some spots the anomaly exceeds 4C. Of course that is a fair way off being two weeks away, but if it did happen, it would certainly act to boost temperatures, particularly overnight.

UKV has backed off slightly today but still going for 25C both Saturday and Sunday. I'm still pretty sure we'll tick that one off the list. The next key will be the 30C mark - another warm spell later on in May could well do the job on that one.

Another warm day here. Cloud did take a fair while to burn back mid-morning and then rebuilt again in the afternoon which limited maxes to 20C. Looks slightly warmer tomorrow.

SunSean Would 'an area of below average barometric pressure' be an acceptable euphemism? (note - feel free to tag me in moans if you want to discuss further, I don't want to get hit with a hammer for derailing the thread)

Another slight downgrade in temperatures for Sunday on tonight's UKV. Still looks like a good chance of 25C on Saturday and/or Sunday though. But now somewhat less notable than if we had seen high twenties. Still a definite warm to locally very warm feel to things over the next few days. By Monday, cooler weather moves in from the west but some eastern areas may yet scrape out an additional warm day. Beyond early next week, currently the ECM meteograms are showing a gradual fall in temperatures to just above the 20-year average by around Tuesday or Wednesday, with predominantly south-westerly to southerly winds being favoured along with significant amounts of rain. Beyond Wednesday at this stage is far too uncertain, the ECM wind plume just loses the plot altogether and winds could be coming in from virtually any direction. This is likely due to the uncertainty in positioning of the trough. Summary In short whilst a wetter and somewhat cooler start to next week is likely, temperatures are still forecast at this stage to be near or slightly above average. Beyond Wednesday I think is still too far ahead at this stage. For the second half of next week options include a quick return to high pressure or a more prolonged unsettled period. At this stage it's impossible to call, frankly.

MP-R 27C is quite unusual in the first half of May. It's only 3C below the highest temperature recorded at that point in the year! Not talking about May as a whole here. In any case, this morning's UKV downgraded to 26C - we'll see what the evening run brings. Alderc 2.0 Generally about 1C or so lower across most areas with a greater drop further south and west. We'll have this evening's run to compare to as well. Still some variation about Sunday - options available that keep warmth into Monday or Tuesday and others clear it earlier. We will have to wait for a few more runs to be sure.

jonboy Well, the only way for certain will be to wait for the effects to mix out of the system. I think Robert Rohde had some stats on the stratospheric H2O content - I'll have to see if the graph has been updated.

jonboy There are two counterbalancing forcings - positive (H20) and negative (SO2).

Daniel* I totally agree, which is why I said it would require a further upgrade - just making the point that if we see 27C in the modelling it wouldn't take much of a tweak. As it happens the model has moved slightly the other way this morning - max for Sunday is down to 26C.

reef How about a 16C May I'm only half joking based on some of the output...

For the shorter range, as I've just posted on the model thread, UKV has amped it up yet again. An absolute max of 27C now showing for Sunday. If this verified, all the CET stations would record 25-27C. If it clouded over Sunday night as is very possible and minima stayed in the low teens, we could be looking at a 20C mean. Bonkers.

Scorcher Definitely not a common occurrence historically, no. But without going off topic it just happens so easily these days. I mean we don't even have a spectacular setup - soils are quite wet, there's still expected to be a bit of wispy cloud around, SSTs are still relatively cold though warmer than average, and the sun is still a fair way from peak strength. Of course by Sunday it will be equivalent to the very end of July, so not that weak any more, but still a factor especially when combined with the others above.

For the shorter range, worth looking at UKV for the next few days on temperatures. Temperatures for Wednesday through Sunday afternoons below at 850hPa and then at the surface. In short, a growing tendency to bring increasingly warm air in at 850hPa. Notable increases in predicted temperatures compared even to yesterday's output - getting 10-11C at 850hPa by Sunday and temperatures quite widely into the mid-20s. Day by day, UK maxima are projected by the model from at 20C, 22C, 23C, 25C and by Sunday 27C, and again if usual slight underestimation were to apply maybe 28C somewhere on Sunday? Worth remarking actually how warm this is for so early in the year. For a bit of context the earliest 30C ever achieved is on the 12th May, so we're only a couple of degrees off all time records for the time of year. It would only take a very slight upgrade to put 30C on the table for Sunday. What a turn around from late last week, when there was talk of temperatures being limited to low 20s only. On Saturday and Sunday those temperatures should be reached by 9am if UKV is right!

After a cloudy and cool morning here quite a nice afternoon in the end - only around 17-18C but still feeling warm.

Showing how things can change even at relatively short range - GFS 18z fractionally stronger with the high at day 5. Interesting to see what happens further down the line...

Derecho Looking at the ECM clusters here. For days 5-7, slight disagreement over how long any high pressure lasts for. All have it still in place at day 5 (Saturday), all except cluster 3 maintain it to day 6, but decent consensus on a breakdown by day 7. After that, there seems to be good agreement on a largely unsettled outcome for days 8-10, though there is some variation on exactly how unsettled. However, the day 11-15 clusters look quite different. All 3 clusters look unsettled at day 11, but only cluster 1 remains unsettled at day 15. Clusters 2 and 3, which make up two thirds of the ensemble members, return to a settled outcome by day 15. I think about all we can say at the moment is that on the basis of this you'd expect a cooler and more unsettled pattern relative to this week to kick in by around days 7-8. But there is a big question mark over whether it is a brief unsettled period lasting a few days or something more prolonged.

LetItSnow! Probably still far too early to do more than speculate about second half I think. Hopefully the broad-scale pattern at the seasonal level will reconfigure to something like the opposite of our current 10 month pattern, e.g. a move from troughs and occasional ridges to ridges and occasional troughs. We're not going to go months and months without any unsettled weather at all, but it would be nice if for once we could have this week mainly settled and warm, a few unsettled days, and then another settled and warm week to follow on.

LetItSnow! Depends on the measure. Some individual stations are almost guaranteed to be wet by rainfall total now - many parts of Sussex as others have said and also based on this evening quite likely West Yorkshire area as well, no doubt there will be others. But those don't add much to the grid average for e.g. the England and Wales Precipitation series. The other point is rain days - I find that these correlate much more with the experience of a month. I'd much rather we had a May with average rainfall overall but with half a dozen very heavy rain days from thunderstorms and the rest mainly or entirely dry, than 50% below normal rainfall with constant light showers and drizzle.