Deputy Chief Meteorologist
@metoffice
. FRMetS, CMet, Roostmaster.
@RMetS
'Weather' News co-editor. World famous speedcuber. Personal account, views my own.
GFS 06Z run producing 42-43ºC as a maximum
#temperature
for the 17th July... here's some points of interest from a meteorological, and climatological point of view...
Comparison of
#StormCiaran
vs the 1987 "Great Storm".
Similar central pressure, but Oct 87 moved faster, had slightly stronger winds, and a more northerly track, bringing them across SE UK.
Most similar for NW
#France
and
#Jersey
(85-95kn at 5000' in Ciaran, vs 100 kn in 1987).
Some extreme low pressure solutions showing up next Thurs, eg 28/12Z MO GM at 949hPa at 06Z
This would challenge November
#UK
records, 948.4hPa at
#Aldergrove
on 06Z 30/11/1954 the lowest currently in the MIDAS dataset
Other notable lows - 949.3 (11/11/10), 950.4 (13/11/91)
I've built a page which allows you to look back at previous runs, to help more easily identify model trends.
Check it out here -
An explanation of how it works is available on the left of the page. Thanks to
@wxcharts
for allowing me to use their images.
A special
#Christmas
chart/card for all my followers... a non traditional frontal analysis but a festive one nonetheless.
It's been great to have been part of the community and to share weather facts and stats with you all over this past year.
Have a great Christmas everyone!
Probably post night shift tiredness talking, and to no-one in particular, but:
The Met Office don't issue medium or high impact warnings lightly. If we go RED, it comes from the culmination of intense analysis/discussion between experts in the field
Take them seriously, please.
Shockwave from Hunga Tonga-Hunga Haʻapai eruption plume, seen by pressure change at UK sites. Wave moves southward down the country 18-20Z 15Jan. The same wave, but travelling the other way around the globe, moves northward up the country 01-03Z 16Jan.
@RoostWeather
@Silkstiniho
With a reading of 983.0hPa on the 1300Z ob,
@RNASYeovilton
has recorded its lowest August mean sea level pressure since its record began in 1965.
Previous lowest was 983.8hPa at 0700Z on Aug 30 1992.
983.9hPa the low at the Roost!
Wow it's even better now, a wonderful example of Shapiro-Keyser cyclogenesis -
#StormAgnes
There must be a sting-jet occurring, with prominent striations at the tip of the cloud head. I have a vague idea they might be called "Scorer's fingers" - though I can't find a source.
It appears a large number of stations (and there will be more than shown here) have now broken their September max
#temperature
record in this hot spell... including
#Larkhill
where the POR goes back to 1921.
@extremetemps
81mph at
#Exeter
Airport No2 a record for the site which opened in the early 1990s, and the 3rd strongest at Exeter Airport overall (including the original ob site).
Only 83mph on 28/02/1990 and 85mph on 25/01/1990 (Burns Day Storm) were stronger.
#StormHenk
#StormHenk
Strongest
#wind
gusts (>=30mph) so far today (2nd Jan) from the 03xxx SYNOP sites (<250m altitude).
#Exeter
Airport No 2 currently top of the pile with a
#gust
of 81 mph at 1250Z
So,
#rainfall
at
#Honister
Pass in
#Cumbria
still going - now up to almost 340mm since the start of the
#warm
conveyor event yesterday morning.
298.8mm in a 24 hour period, which is right at the very top of observed
#climate
, even for this very wet site.
On the night of the 15th and early hours of the 16th October 1987, the "Great Storm" devastated the south of
#England
, with gusts in excess of 100mph recorded in the far southeast
Here are the highest gusts at each official site (all occurring on the 16th), gusts >=50mph plotted
Massively hacked together and very last minute, but here's a map of
#November
minimum sea level
#pressure
(from MIDAS) for as many counties as I could match between datasets.
Some records will fall over the next 24 hours!
#StormCiar
án
Explore it here -
Exceptionally deep low (933 mb) over the far North Atlantic signalled in the latest forecast chart from the
@metoffice
- valid midday Fri 4th.
This the result of the extratropical transition of Hurricane Martin, in a similar manner to Fiona which struck Canada earlier this year.
Didn't even occur to check until
@danholley_
mentioned it, it's actually the wettest month on record for any month, beating November 1970 (156.2mm). And we are only 2/3 through!
Convection over
#Denmark
this afternoon produced a fantastic outflow boundary, visible as an undular bore rippling through the low cloud sheet over German Bight in the eastern North Sea.
Imagery courtesy of
@eumetsat
In summary, it seems like achieving these temperatures is realistic in terms of the modelling, but requires conditions so far outside the recent climate that it seems hard to believe.
However, our warming climate means that we probably underestimate the chance of it happening.
With
#StormEunice
having departed, comparisons have been made with the Great Storm of October 1987, and the Burns Day Storm of January 1990.
Here are the top
#gusts
in mph for each event, gusts >=60 mph shown.
Clearly
#Eunice
was a notch or two down on these.
I've built a page which you can use to find out the daily extreme maximum
#temperature
for any date in the year, using the NCIC OpenMIDAS database + SYNOPs to fill in the gaps.
Read the notes at the bottom of the page!
@markpmcc
With the
#UK
#weather
focus (rightly) being on the now 50/50 chance of touching an unprecedented 40ºC maximum
#temperature
on Tuesday 19th July, here's a couple of other potential records to watch out for from a meteorological interest point of view...🧵
With a stonking 156.8mm of rain so far this
#July2023
,
#Blackpool
has already had its wettest July on record, with still 1 week to go...
Currently at 340% of normal for the first 23 days of July.
#Rainfall
records here go back to 1957.
Check out my latest page - see how many days each year the
#temperature
in the
#UK
exceeded a threshold of your choosing (between 20ºC and 40ºC).
Click on the table below the graphs to see the details of individual days. Read the notes!
#Autumn2022
really out on a limb in this plot of
#temperature
vs
#rainfall
covering the years 1884-2022
Not long to go, looks like it will be easily the warmest Autumn on record in the
#UK
, and with the wet Nov, close to average in terms of rainfall despite the dry Sep and Oct.
It looks like
#December2023
is going to be one of the dullest Decembers across the
#UK
in 108 odd years...
...but spare a thought for the residents of Bala in NW
#Wales
, who have seen just 3.8 hours of
#sunshine
so far this month, likely the dullest in over 50 years.
Rainfall over the past 2 days and 3 hours, from official
#rain
gauges. Totals >=100mm plotted only.
Some quite incredible, and widespread large totals across
#Scotland
, almost 180mm at Hazelwood Cottage, 105.0mm of which fell in just 12 hours, 137.8mm in 24.
Significant impacts
With help from
@danholley_
here's a gust map (mph) for
#Ireland
and
#NorthernIreland
, with some private sites (italic) alongside official obs.
The strongest gusts in
#StormDebi
bisected the official obs almost perfectly, and appear to be assw the most intense cold conveyor flow.
Just for interest, here's what the maximum
#temperature
summary looked like for the 28th June 1976, which is when the
#June
record maximum of 35.6ºC at Southampton, Mayflower Park was recorded.
With thanks to
@danholley_
(and
@SnowbieWx
,
@northyorkswx
for additional contributions), here's a (more-or-less) final map of highest
#gusts
from
#StormDebi
(>=50mph).
Purple circles are private sites, purple squares are road sites, and green squares are additional official obs.
The signal for large hail over southern
#England
today has been strengthening in
@essl_ecss
product over the past 24 hours... below is the 12/00Z run, panels valid 12-15 and 15-18 UTC (BST-1 hour).
Refer to
@metoffice
services for the official line!
Some dramatic pressure falls being observed in the southwest now as
#StormCiaran
approaches...
...a fall of 14.3mb in 3 hours on the 21Z
#Camborne
ob, and currently falling 12.7mb in 3 hours at my own station. Just dropped below 970mb too.
The 64.8mm recorded at
#Exeter
Airport in the period 16/21Z to 17/21Z was the 2nd wettest such 24 hour period on record, and the wettest day in over 50 years.
Only the 90.3mm on 19/07/1972 was higher.
Using this revolutionary new ensemble technique, I would go for a peak max of 33ºC later this week, but it seems that anything between 29ºC and 36ºC remains possible.
Radar estimated accumulations over the past 18 hours (10pm yest to 4pm today), in the
#thunderstorms
and heavy
#rain
Areas of 60-80mm, and the odd pocket of 80mm+
A nice example of a diffluent block (also known as a Rex block) setting up later this weekend over Western
#Europe
- seen from the perspective of my T+120 chart.
10 days after the MJO entered Phase 7 as well!
Using this revolutionary new ensemble technique, I would go for a peak max of 33ºC later this week, but it seems that anything between 29ºC and 36ºC remains possible.
As the heat spread quickly NW last Saturday, mountain site Bealach Na Ba in W
#Scotland
recorded an all-time record maximum
#temperature
of 22.9ºC, beating its previous high of 22.7ºC set in July 2006.
Observations back to July 2001.
At least 23 official sites have also (provisionally) broken or equalled their November maximum
#temperature
record!
Some of these records going back 90-100 years.
#Rainfall
totals >=50mm over the past 48 hours
#StormBabet
171.6mm at Waterside Perth in east
#Scotland
the largest amount, 169mm of this in 24 hours.
Another up to 100mm possible here over the coming 24-36 hours, with a new
@metoffice
RED warning issued.
In the UK daily precipitation series, which goes back to 1931, SE Eng (and Cen Eng, not shown), has had its driest first 13 days of Feb on record, with just 0.74mm total
#rain
recorded.
Other dry years include 1934, 1959, 1964, and 1993.
Eng & Wal overall currently 3rd driest.
Today I launched a major upgrade to my observations, getting rid of several maps and combining them into one universal display.
There's an in-page version -
and a full screen version -
All connected to my seamless obs database!
I've added a page which allows the user to look at the state of the stratospheric temperature and winds (as analysed by GFS) over the past 30-days, in map form.
Plots are kindly taken from
@zd1awrence
great site.
For the first time since the major
#SSW
on Feb 16th, the tropospheric NAM index has turned negative (as per the definition from NOAA Climate Prediction Centre).
In very broad terms, a negative NAM represents weaker than average westerly winds at mid-latitudes.
#weather
#climate
Quality controlled
#UK
maximum
#temperatures
from the
@metoffice
OpenMIDAS dataset are now available on my maximum temperature summary map... data back to 1853!
Let me know what you think, and especially if you find any bugs!
This is what you call explosive cyclogenesis! 😍
993mb -> 945mb, drop of 48mb in 24hr as per the official
@metoffice
analyses. Twice the rate of deepening required for a "bomb" (at 60ºN).
Also check out the orographic cirrus in lee of Pennines at the end!
Video h/t
@eumetsat
Expanding the series of extreme
#temperature
maps, I've now got daily, monthly, and yearly extreme minima from official sites available.
Check them out, let me know what you think/if you have any problems!
Numerous
#wildfires
across
#Canada
in combination with a very zonal (straight) jet stream across the Atlantic is causing a significant amount of
#smoke
to be drawn across the
#UK
currently.
Also pulled south into the circulation of
#Ernesto
Imagery from
@NASA
Worldview
Breaking news...
Monthly *maximum* CET for June 2023 has come in at 22.6ºC, toppling the previous warmest June (by this measure) which was 22.5ºC in *1976*
Possibly this is more notable than the mean temperatures, as the max temperatures are what most people experience...?
6 hours of integrated
#radar
from 3pm to 9pm, with a core of highest totals centred just east of
#Bradford
city centre.
#Flooding
was reported, with this suggesting a peak accumulation of 67mm during this period.
(1/3) Some more maps for the weekend...
In addition to my daily extreme max map, I've now added monthly and all-time max
#temperature
records for the ~1550 sites in Open MIDAS, supplemented by SYNOPs where available...
Met Office warnings, 0005Z Fri 18th Feb.
Watch out for further reds - if issued this will indicate increased confidence of high impacts.
BUT - if in the Amber warning area TAKE NOTE, conditions could be EQUALLY as severe, we are just not quite as confident yet.
#StormEunice
Just looking back at the cold spell earlier in the month, and marvelling at the switch back to milder than average (1981-2010) conditions which swept rapidly NE across the UK between the 18th and 19th.
Merry Christmas to all my followers, hope you have a wonderful day, whatever you're doing.
My Christmas thought: try not to get too worked up over individual model runs and even model trends, uncertainty is inherent in meteorology; you can't change the weather!
Dan @ the Roost.
At 9.0ºC, the mean minimum
#UK
#temperature
was a full 2.7degC above the 1991-2020 climate average.
This was the primary driver for month overall being the warmest May in the 141 year record.
A number of sites reporting >100mm of
#rain
in the first 4.5 days of
#October2022
- and look at the west/east split!
Allt Dearg House on Skye on 211.0mm, East Anglian sites (until this afternoon) less than 1mm.
The daily minimum Central
#England
#Temperature
for
#December
9th was -5.1ºC, which was the second coldest Dec 9th in the daily min record which goes back to 1878.
Only 1967 was colder 🥶
A comparison of
#StormEunice
, St Jude's Day Storm, Burns Day Storm, and the Great Storm of 1987, using monthly station gust climatologies (
#UK
only, sorry
#Ireland
).
Max gust in 99th percentile or greater plotted only.
2023 joins an exclusive club of years where the
#UK
monthly Tmax for both Jun & Sep was higher than both Jul & Aug
The last time this occurred was 1940, and has only occurred 6 other times since the mid 1850's
1865, 1889, 1891, 1895, 1939, and 1940. Data: MIDAS
@extremetemps
24 hours of
#rainfall
from my guesstimated
#radar
, 06/21Z - 07/21Z. White = 50-75mm, Grey 75-100mm, Black 100-125mm, Yellow 125mm+
The very large area of 75mm+ is likely to have been responsible for such extensive
#flooding
that has been reported.
Saw some great
#sunset
pictures from last night, and here in mid-Devon we had a particularly spectacular sunset too. Here's my favourite from the set.
#loveukweather
@metoffice
Percentage of average
#rainfall
for the first 12 days of
#February
, that has fallen this month.
Extremely dry across much of the
#UK
so far, except the far N of
#Scotland
which has actually been wetter than average.
Channel Islands currently experiencing the most intense winds in the cold conveyor of
#StormCiaran
- the centre of which can be seen near
#Southampton
A less strong (but still strong) swathe slowly moving E across
#Cornwall
, moving across
#Devon
soon but winds slowly reducing.
Absolute stunner of a visible satellite picture courtesy of
@NASA
of a
#thunderstorm
propagating offshore of the Somali coast on May 5
Check out the "updraftlets" all ready and waiting to be hoovered up by the main cloud! Not seen anything like that before. Wave action?
At least 50 official sites recorded their lowest 5th August max
#temperature
, and more notably, 4 sites in Midlands and East Anglia, with records as far back as 1991, recorded their lowest
#August
daily max temp for any date.
Incredibly sharp edge to the extensive and widespread cirrus currently over
#France
and the Low Countries, which hasn't moved very much in the past few hours!
It's feasible that
#SaharanDust
has increased the cloud ice content within this system relative to "normal"
#thunderstorms
developed and ran N over the past few hours; a train of particularly nasty ones affecting
#Dartmouth
,
#Totnes
, and up towards E
#Dartmoor
.
Private gauges report 60-75mm of rain, supporting
#radar
estimates of 64-80+mm.
Another nasty swathe heading for
#Sidmouth
.
Some really cool constructive and destructive interference patterns in these waves being reflected off the
#sea
wall, mesmerising to watch!
#SummerHolidays
#StormIngunn
is a rather complex cyclone, arising from multiple "baroclinic streams"
This coloured WV
#satellite
image may evidence two simultaneous, separate sting jets, the bright yellow features emanating from the tips of the two cloud hooks - one just west of the
#Faeroes
A new visualisation - Central
#England
#Temperature
daily anomalies. Plenty to customise, check it out and let me know what you think.
Here's the last 10 or so years of
#December
Link from my
#CET
tracker -
Lightning strikes over the past 24 hours... red are the most recent, through the purple... you can really see the how the different elements of the system evolved through this period.
Just looking through yesterday's
#weather
data here at the Roost, and noticed some remarkable
#pressure
fluctuations...
...a drop of 4mb in 10 minutes at around 1630Z, did anyone else notice similar?
Still a week to go of course, but my crude estimates from SYNOPs highlighting, if things continue as is, the potential for this
#July
to be one of the hottest, and driest, on record here in the
#UK
overall.
This great IR image from
@eumetsat
taken just a couple of hours ago reveals the wave nature of the planetary scale flow in the mid-latitude atmosphere.
Last 6 hours of guesstimated integrated radar accumulations.
93.6mm over Central
#Scotland
the highest amount, may or may not be hail contaminated. Some of the peak totals are for sure.
Very pleased with how this has turned out... custom built live data display for my site, powered by Davis VP2, Meteobridge PRO2 and my own dodgy coding skills!
Taught myself some javascript along the way too.
#wxtwitter
#CodingJourney