It's that time of year again time never stands still; last summer seems a distant memory, forecasting this summer presents particular challenges. The teleconnections or signals atmospheric/oceanic which govern the weather we see, are not particularly strong and are conflicting with one another. In contrast to exceptional summer that was 2018 in which the blueprint for the summer began in May and continued well into August. As such all forecasts should be treated particularly cautiously, as possible scenarios, a lot can and does change in season after all this forecast is a breakdown and analysis of current state of play. Of systems which are fluid. This summer we are set to experience a weak Nino and neutral to positive PDO these parameters help support fine, warm weather nonetheless they are not particularly strong, which may weaken their positive influence. As such one should not expect a washout summer which is devoid of lovely weather like 2007 this does not present itself; however there is likely to be cooler and unsettled weather punctuated through summer. This will give rise to thundery outbreaks which 2018 disappointed in that department.
*Not a poor summer but not a great one either **
Summer 2019 forecast summary
Temperature: near average most likely to fall within 0.5 both -/+ of 1981-2010 average
Precipitation: normal to above
'Middle loaded although extending into August'
June
June is rather likely to experience wetter than average conditions with persistent negative AO/NAO state (high pressure across pole, lower pressure in mid lats affecting UK and Ireland) probable pronounced by the current second lowest sea ice extent on record & low solar. Furthermore, the Atlantic SSTs are not particularly promising with it possibly reflecting in storm track perhaps being further south than usual and subsequently lows steered our way. The start of summer has seen suppressed convection in Pacific atypical and typical in La Niña state there are encouraging signs later in the month, we may see a reversal. Taking a more Nino signature which we should be seeing, this is good as 2007 and 2011 (washout summers) both featured strong La Niña which reinforced a very blocked pattern not conducive for longtime warmth. This expected uptick will have corresponding effect of ridges of HP being able to truly take a foothold so while I believe much of month will not be particularly warm or settled, there is a good chance of something much more along those lines late in month while also not being a fleeting affair.
Temperature: below average
Precipitation: above average particularly in N/W
July
Confidence truly slips away at this period however if expected uptick in tropical forcing happens later in June there is broad expectation July will be largely anticyclonic and warm. Everywhere particularly in the south and east in which it may turn hot at times although nothing overly unusual in a typical summer. At least in the first half of the month widely, and I do believe it is more likely to be the warmest month of the summer. Overall through this month this warm weather may be punctuated by cooler Atlantic air, this will cause thundery outbreaks and rain, so indeed a better summer for those storm 'chasers' out there? It may be a month which has a pronounced E-W split with Atlantic trough backing west however perhaps not enough for Ireland in which I feel summer could be particularly wet and cool.
Temperature: warmer than average
Precipitation: near normal large regional variance
August
Confidence is very low and therefore not much detail can be provided however, it is probable warm summery weather will feature with a greater chance perhaps in first half. There is some signal for a more La Nina signature with a decline in +ve Nino state to neutral verging on La Nina later in the summer this would mean the summer is not likely to finish particularly well. There is also good expectation in conjunction sea ice may be in a truly disastrous state with lowest sea ice extent on record. This could give aid to give rise to return of extensive northern latitude blocking seen early summer, which is why we are currently locked in an unsettled pattern. With increased westerlies seen with seasonal change August could finish unsettled although much of month may be pleasant beforehand.
Temperature: above average generally
Precipitation: near normal
Thanks for reading I sense this summer will help alleviate drought fears a respectable summer it is looking.
Dan
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