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April 2021 C.E.T. and EWP forecast contests


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Posted
  • Location: Broxbourne, Herts
  • Weather Preferences: Snow snow and snow
  • Location: Broxbourne, Herts
    6 hours ago, Summer Sun said:

    6.2c to the 6th

    0.3c below the 61 to 90 average
    1.4c below the 81 to 10 average

    ___________________________

    Current high this month 8.8c on the 1st
    Current low this month 6.2c on the 6th

    Tumbling!

    I think I went about 7.7C for this month.  If my recent form is anything to go by, expect to see that as the figure to the 27th, followed by a warm up to 8.5C by the end of the month!

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    I think the headline should include "exceptional frosty". We've had sunny and very dry Aprils in the past but rarely has an April has been this frosty.

    Excel April 21 CET.xlsx PDF (Summary)April 2021 Summary.pdf The cold April caught everyone out this month, in February we also had the weather models predicting a cold start to the month and

    My mean temp is currently running at 5.7C (-3.0C) to the 29th. In records back to 1980, the coldest was April 1986 with 5.8C. This month will beat that if tomorrow averages 7.1C or below. For ref

    Posted Images

    Posted
  • Location: Rossland BC Canada
  • Location: Rossland BC Canada

    I was saying that a cold and dry April is an unusual combination. So I checked the data, EWP data go back to 1766, so for the 59 Aprils in that period with mean CET 7.2 or lower, these are the only six of those that had a dry outcome (40 mm or lower) ... for those that did not, I show which category (near normal 40.1 to 80.0, wet 80.1 and above) they fell into. The dry outcomes are listed in EWP order, the others are just chronological. 35 were near normal as defined and 18 were wet. The chance of a cool April being wet seemed to increase towards the end of the period. This may indicate that when cold air does dominate in the region, the storm track has recently begun to lift up closer to the CET zone. 

    DRY __ 1855 (19.9),1806 (26.8), 1771 (31.3), 1929 (34.9), 1887 (36.6), 1839 (38.8)

    N N __ 1770, 1772, 1777, 1780, 1782, 1790, 1793, 1804, 1812, 1816, 1823, 1836, 1837, 1838, 1847, 1860, 1879, 1884, 1888, 1890, 1891, 1897, 1903, 1908, 1917, 1918, 1919, 1924, 1935, 1941, 1951, 1956, 1973, 1977, 1978, 

    WET __ 1782, 1784, 1799, 1808, 1809, 1818, 1829, 1849, 1877, 1889, 1922, 1932, 1966, 1970, 1983, 1986, 1989, 2012

    _________________________________________________-

    Even the small sample of cold, dry Aprils were mostly "moderately dry" -- only two were held below 30 mm. With the cooler than average temperatures, a precip of 30-40 mm would not result in a very dry soil moisture condition. Of the large number of "near normal" cases there were probably a majority in the 40-60 range. A cooler than average April is subject to more precip in northerly flows and the troughs that develop, which can lead to persistent and possibly wintry falls but not particularly heavy ones in many cases. A drenching cold April like 2012 is the exception. 

    At the moment the GFS indicates quite cold weather to continue to about the 22nd then a shift to warmer temperatures, so it is not a guarantee that 2021 will finish as cold as 7.2, but nowadays probably 7.5 is about as cold as 7.2 used to be in terms of a pattern, I find that the colder weather nowadays has a barder time establishing low daily averages, there's a tendency for some of the potential to be lost due to a first day of a cold spell needing all day to get the air mass into place, etc. The pattern ahead also looks fairly dry. Note that we have not seen a cold, dry April as defined here since 1929. 

     

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    Posted
  • Location: Manchester
  • Location: Manchester

    CET has dropped significantly and there's still a week or so of cold weather to come. Low 5s seems likely at mid month. But a warm up similar to 2019 could possibly rise that to average. We'll see

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    Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.

    I might have to eat a huge slice of humble pie to BFTV if this keeps up, although i still can't see it finishing in those ridiculous categories and can't see it finishing massively below 8c, remember only a week of very modest uppers like 0c or -1c will bring max's in the teens so it will shoot up late in the month.

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    Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl
    1 hour ago, feb1991blizzard said:

    I might have to eat a huge slice of humble pie to BFTV if this keeps up, although i still can't see it finishing in those ridiculous categories and can't see it finishing massively below 8c, remember only a week of very modest uppers like 0c or -1c will bring max's in the teens so it will shoot up late in the month.

    This is the fifth month in a row when the opening 10 days has been either colder or just about near average, we've then had warm ups in the second half especially so in Feb and March. In January there was no real warm up. In December the warm up came mid month and then we had a drop. Indeed look at the CET tracker last 5 months and its been a major roller coaster.. lots of ups and downs, making for a much more interesting spell of weather for quite some time, generally any dips have been less steep and shorter in duration and its often been a high plateau line, or slight wobbles on a warm line..

    Too early to call how April will finish, but it does look like we will be significantly below average by mid month, coldest first half to April since???

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    Posted
  • Location: Ireland, probably South Tipperary
  • Weather Preferences: Cold, Snow, Windstorms and Thunderstorms
  • Location: Ireland, probably South Tipperary

    Assuming 5.5C mid month, for the second half of the month we'd need to average:

    6.4C to reach 6.0C (achieved in 96% of previous years)
    8.4C to reach 7.0C (achieved in 59% of previous years)
    10.4C to reach 8.0C (achieved in 25% of previous years)
    12.4C to reach 9.0C (achieved in 2% of previous years)

    That's all excluding the end of month corrections.

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    Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield

    Sunny Sheffield down to 5.4C -1.7C below normal. Rainfall unchanged.

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    Posted
  • Location: Ireland, probably South Tipperary
  • Weather Preferences: Cold, Snow, Windstorms and Thunderstorms
  • Location: Ireland, probably South Tipperary

    Latest projections

    AprilProj8.thumb.png.73048660a9e6e42a5e45faab33c0a4da.png AprilProb8.thumb.png.aa71ec31bd736e4a5f264f1332b72b38.png

    The chances of finishing:
    Close to average (8.5C to 9.5C) is 🔻to 7.7% (3 days ago 11.7%)
    Above average (>9.5C) is 🔻to 0.0% (3 days ago 0.4%)
    Below average (<8.5C) is 🔺to 92.3% (3 days ago 87.9%)

    The period of the 8th to the 13th is forecast to average 5.0C, which is 3.3C below the 91-20 average.

    I've noticed that the GFS has had quite a consistent cold bias throughout the month so far, typically about 2C too cold at night, and 1C too cold during the day.

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    Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

    5.8c to the 7th

    0.7c below the 61 to 90 average
    1.7c below the 81 to 10 average

    ___________________________

    Current high this month 8.8c on the 1st
    Current low this month 5.8c on the 7th

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    Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
    15 hours ago, damianslaw said:

    coldest first half to April since???

    Not sure - did 12 or 13 beat it - 08, if not which i don't remember any severe cold in those spells, could of been sometime in the mid 80's cant remember anything too severe in 90's and naughties although did recall seeing some white easters in the mid 90's - 86??

     

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    Posted
  • Location: Windsor
  • Weather Preferences: Snow and cold
  • Location: Windsor
    2 hours ago, feb1991blizzard said:

    Not sure - did 12 or 13 beat it - 08, if not which i don't remember any severe cold in those spells, could of been sometime in the mid 80's cant remember anything too severe in 90's and naughties although did recall seeing some white easters in the mid 90's - 86??

     

    I remember Spring 1989 after a miserably mild winter delivering a few snowy spells in Yorkshire!

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    Posted
  • Location: Edinburgh (previously Chelmsford and Birmingham)
  • Weather Preferences: Unseasonably cold weather (at all times of year), wind, and thunderstorms.
  • Location: Edinburgh (previously Chelmsford and Birmingham)

    Recent first halves (1st-15th) of April to beat are:

    2013: 5.8C
    2008: 6.7C
    2000: 5.6C
    1998: 6.6C
    1996: 6.5C
    1994: 5.8C
    1990: 6.7C
    1989: 6.5C
    1986: 4.4C
    1984: 5.6C
    1983: 5.6C
    1978: 5.4C
    1977: 6.2C
    1975: 5.6C
    1973: 6.3C
    1970: 4.7C

    We stand a chance of beating all those since 1986, although that's far from nailed on. A slim possibility we end up third coldest since 1970.

    Edited by Relativistic
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    Posted
  • Location: Rossland BC Canada
  • Location: Rossland BC Canada

    Also if you're wondering about a longer-term list of cold starts to April, I posted a list of those back on Friday 2nd (below 3 C in 1917 and 1837). 

    Continues to look like a slow warming trend after the 20th and overall rather dry. 

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    Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl
    4 hours ago, Relativistic said:

    Recent first halves (1st-15th) of April to beat are:

    2013: 5.8C
    2008: 6.7C
    2000: 5.6C
    1998: 6.6C
    1996: 6.5C
    1994: 5.8C
    1990: 6.7C
    1989: 6.5C
    1986: 4.4C
    1984: 5.6C
    1983: 5.6C
    1978: 5.4C
    1977: 6.2C
    1975: 5.6C
    1973: 6.3C
    1970: 4.7C

    We stand a chance of beating all those since 1986, although that's far from nailed on. A slim possibility we end up third coldest since 1970.

    Don't remember too much about April 2000, though think there was a general low level snowfall on the 2nd, not often mentioned.. 

    Interesting to note the number of years that had very mild Jan-March periods, notably 2008, 2000, 1990 and 1989..

    April 1986 though came on the back of the freezing February and cold March. What a year 1986 was for cold weather.. Jan was quite chilly, Feb last sub freezing one, March, April, August and September - the last two months notably cold. However, the last three months of the year were milder than average.

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    Posted
  • Location: near Edenbridge - 178ft
  • Weather Preferences: Cold snowy winters and cool, wet springs and summers.
  • Location: near Edenbridge - 178ft
    21 minutes ago, damianslaw said:

    Don't remember too much about April 2000, though think there was a general low level snowfall on the 2nd, not often mentioned.. 

    Interesting to note the number of years that had very mild Jan-March periods, notably 2008, 2000, 1990 and 1989..

    April 1986 though came on the back of the freezing February and cold March. What a year 1986 was for cold weather.. Jan was quite chilly, Feb last sub freezing one, March, April, August and September - the last two months notably cold. However, the last three months of the year were milder than average.

    Won’t go too off topic but was only thinking earlier what if the last three months of 1986 hadn’t gone mild, or even stayed relatively close to average. If that Jan. 1987 had occurred a month earlier  it would have been a remarkably cold year. Certainly was a cool/cold lovers dream from Jan. 1985 all the way until Aug. 1987. I hope I live to see a spell like it in my lifetime due to sheer interest. 

     

    Diversion over!

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    Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL

    Plenty of cold if very cold nights to come. CET will tank further! 

    9CAE3ABB-E20E-47F2-ABB0-75BD3F9B5D62.thumb.png.ed22d7abeb5c9ddf27fa58b54205aaa9.png63E409CB-97EF-4827-93C1-D20EA6D88C81.thumb.png.91d14af921034e504fd3a30ccf3af454.png0483DA6F-2170-4BDD-8163-B130D126880C.thumb.png.566536ac1e3bd7cb1b97d2fed8fc97ad.png

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    Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield

    Sunny Sheffield back up to 5.5C -1.6C below normal. Rainfall 1.4mm 2.5% of the monthly average.

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    Posted
  • Location: Rossland BC Canada
  • Location: Rossland BC Canada

    For continuity ... 

     

     

    5.9c to the 8th

    0.6c below the 61 to 90 average
    1.6c below the 81 to 10 average

    (2.2 below the 91 to 20 average)

    ___________________________

    Current high this month 8.8c on the 1st
    Current low this month 5.8c on the 7th

    =====================================

    EWP update 

    ... tracker working now, 1 mm to 7th, possibly 1 mm yesterday, so sitting at 2 mm ...

    ten day GFS suggests 10-15 mm, days 11-16 look a bit more active, 10-15 more? 

    That would lead to an amount near 30 mm by the 25th. 

    The CET projection looks continued cold for about a week then closer to normal, wouldn't call any day later on warm for late April but several days would be near or slightly above normal. That would all argue for a gradual rise into the mid to high 6 range and we could be near 7 C by the 25th. Unless this month does a 1775, it would be a challenge to get past 8 C from there. 

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    Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl
    21 minutes ago, Roger J Smith said:

    For continuity ... 

     

     

    5.9c to the 8th

    0.6c below the 61 to 90 average
    1.6c below the 81 to 10 average

    (2.2 below the 91 to 20 average)

    ___________________________

    Current high this month 8.8c on the 1st
    Current low this month 5.8c on the 7th

    =====================================

    EWP update 

    ... tracker working now, 1 mm to 7th, possibly 1 mm yesterday, so sitting at 2 mm ...

    ten day GFS suggests 10-15 mm, days 11-16 look a bit more active, 10-15 more? 

    That would lead to an amount near 30 mm by the 25th. 

    The CET projection looks continued cold for about a week then closer to normal, wouldn't call any day later on warm for late April but several days would be near or slightly above normal. That would all argue for a gradual rise into the mid to high 6 range and we could be near 7 C by the 25th. Unless this month does a 1775, it would be a challenge to get past 8 C from there. 

    Might end up with a colder April than March, when was the last time that happened? Can't be many instances.

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    Posted
  • Location: near Edenbridge - 178ft
  • Weather Preferences: Cold snowy winters and cool, wet springs and summers.
  • Location: near Edenbridge - 178ft
    43 minutes ago, damianslaw said:

    Might end up with a colder April than March, when was the last time that happened? Can't be many instances.

    2012 is the last (7.2 vs 8.3)

    1990 before then (8.0 vs 8.3)

    then 1989 (6.6 vs 7.5)

    interestingly, 1991 almost did the same (both 7.9).  March, 1991 was a bizarre month in that it was well-above average in a general very cool period. IIRC the blocking that led to exceptional cold in February slid further south over Europe/Russia which ended up bringing a lot of very mild southerlies instead. Then the cold pattern resumed in April. 

     

     

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    Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

    6.0c to the 9th

    0.5c below the 61 to 90 average
    1.5c below the 81 to 10 average

    ___________________________

    Current high this month 8.8c on the 1st
    Current low this month 5.8c on the 7th

    Edited by Summer Sun
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    Posted
  • Location: Ireland, probably South Tipperary
  • Weather Preferences: Cold, Snow, Windstorms and Thunderstorms
  • Location: Ireland, probably South Tipperary

    Latest projections

    AprilProj10.thumb.png.ec8825d9cbc159bcb63da4f23d5d46db.png AprilProb10.thumb.png.6f224f37396c73f83e8bf5a8a03a0477.png
    The chances of finishing:
    Close to average (8.5C to 9.5C) is 🔻to 3.6% (2 days ago 7.7%)
    Above average (>9.5C) remains at 0.0% (2 days ago 0.0%)
    Below average (<8.5C) is 🔺to 96.4% (2 days ago 92.3%)

    The period of the 8th to the 13th is forecast to average 4.5C, which is 3.8C below the 91-20 average.

    Some potential low hanging fruit coming up. The record low minima for the 12th and 13th are just -1.7C and -1.4C respectively, and the GFS forecasts something quite close to those values

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    Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield

    Sunny Sheffield up to 5.6C -1.6C below normal. Rainfall 2mm 3.6% of the monthly average.

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    Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
    4 hours ago, Summer Sun said:

    6.0c to the 9th

    0.5c below the 61 to 90 average
    1.5c below the 81 to 10 average

    ___________________________

    Current high this month 8.8c on the 1st
    Current low this month 5.8c on the 7th

    Who's waiting to see if the traditional end of month heatwave will materialise? Anyone who forecasted CET over 9C is out of the game - I can't see us averaging over 12C in the second half. 8C to 8.5C, though, is well within range.

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    Posted
  • Location: Rossland BC Canada
  • Location: Rossland BC Canada

    I think today's 12z GFS run is the coldest I have seen this month in terms of the moderating trend in days 11 to 16, it is almost non-existent with just one brief incursion of near average temperatures. The projected CET by the 26th from this run is only 6.4 C. The map at the end of the sequence shows no signs of that widely expected late warmth, but even if you stuck the 1775 end of April on, it could only add 1.0 to the outcome by then  This run also continues to look quite dry. 

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