The Donegal Weather Channel Monthly Long range forecast issued every week looking up to a month ahead using data from the ECMWF and GFS models.

Please note that the longer range forecasts are more uncertain and should not be used to plan outside activities from over a week out.

Extended Range Output

The output is rather different from the shorter period output of HRES and ENS products.  It provides a more general overview of the forecast up to Day 46, focusing mainly on the week-to-week changes in the weather rather than attempting to give unsupportable detail on individual days.  Output is mostly in the form of anomalies relative to ER-M-climate and is mainly shown as 7-day means for calendar weeks Monday-Sunday.   Specialised products for the extended range also include information on potential tropical cyclone activity and the MJO during the coming month.

SPONSOR THE LONG RANGE FORECAST

If you have a business and would like to sponsor our weekly month long range forecast for a period of 1 week or 1 month please do contact Donegal Weather Channel at info@donegalweatherchannel.ie or message our Facebook page . Donegal Weather Channels service relies on sponsorship/advertising. Without sponsorship/advertising Donegal Weather Channel would not be able to give so many hours and a daily service.

The forecast will be issued by myself Kenneth and i will try to keep it simple making it easy for everyone to understand. If there is a term I use in the forecast which you may not know what it means I will explain what I am talking about .

Before I start with the long range forecast I will just explain what we will be looking at and how the forecast will work.

The forecast will be broken up into 4 section Example below :

• Week 1 - Monday 21st June 2021 -Monday 28th June 2021

• Week 2 - Monday 28th June 2021 -Monday 05th July 2021

• Week 3 - Monday 5th July 2021 -Monday 12th July 2021

• Week 4 - Monday 12th July 2021 -Monday 19th July 2021

Things we will look at in the forecast:

• Mean sea level pressure: Weekly mean anomalies

• 2m temperature: Weekly mean anomalies

• Wind

• Precipitation: Weekly mean anomalies (eg. rainfall and snowfall for a example.

• Dust forecast ( Only in Week 1)

• UV forecast outlook

• Potential Pollen Levels

Forecaster - Kenneth Mc Donagh

Week 1 - Monday 21st June 2021 -Monday 28th June 2021

Mean sea level pressure: Weekly mean anomalies

Over week 1 lower pressure will be across Ireland but over the the end of this week and into the the weekend higher pressure is forecast to position itself across Ireland and just to the west which will bring drier conditions.

Precipitation ( Rainfall ): Weekly mean anomalies

Rainfall amounts over the week gone by where well below average across much of Ireland. Amounts range between 4mm to 20mm. The east and midlands was driest with the western half of Ireland seen the most amounts of rainfall.

Over the coming week rainfall amounts are expected to below normal again for much of Ireland. Rainfall amounts will range between 4mm to 20mm highest amounts across Ulster, Norther Leinster and north Connacht.

• Showery conditions and drizzle is expected across much of the country on Tuesday evening and night.

• Further scattered showers are expected on Wednesday but drier weather will develop from the west on Wednesday evening.

• Thursday currently looks like the wettest day between now and Sunday with a heavy band of rain forecast to move down from the northwest of the country over the day spreading to all areas by Thursday evening and night.

• Further showery weather is expected across Ireland on Friday

• Some uncertainty on this weekend with two mixed scenarios showing on both the American and European forecast models. The European model shows the risk of some showers across Munster and South Leinster with the risk of thunderstorms but drier across the rest of the country with the northern half of Ireland receiving the best of the weather. The american weather model shows a wider risk of thundery showers on Saturday followed by a drier day nationally

• Overall there is a pattern change looking likely to occur over the weekend with higher pressure building which look possibly set to bring warmer weather into week 2.

Rainfall amounts between Tuesday 15th June to Sunday 20th June 2021

ULSTER

Across much Ulster rainfall amounts are expected to be average or just under this coming week. amounts widely will range between 10mm to 20mm.

CONNACHT

Away from west Connacht rainfall amounts are expected to be average or just below this coming week . Highest amounts will be across west Connacht mainly across Galway, Mayo, north Sligo and Leitrim over the higher ground areas with between 10mm to 20mm. Across the rest of Connacht amounts will range between 5mm to 15mm lowest amounts in the south of Connacht.

MUNSTER

Away from south Munster rainfall amounts are expected to be below average this coming week. Highest amounts will be across west Munster mainly across south Kerry & south Cork over the higher ground areas with between 10mm to 20mm. Across the rest of Munster amounts will range between 5mm to 10mm lowest amounts in the east Munster.

LEINSTER

Rainfall amounts across Leinster this week will range between 10mm to 20mm highest amounts will b e across North Leinster and higher ground areas around the Dublin and Wicklow mountains.

Temperature: Weekly mean anomalies

Temperatures over this week (week 1) will be average and just above in some parts of Ireland. There will be no risk of frost this week . Day time temperatures will be in the mid to high teens in the northwest and high teens to low 20s (20C to 21C) elsewhere at times. Becoming warmer over the weekend.

Wind forecast

There are no risk of any strong winds this week. There will be some gusty winds in western and northwestern parts of Ireland on Friday morning and afternoon with a northerly wind.

UV forecast

UV levels will be high this week and possibly very high in places over the weekend .

Pollen Forecast

Pollen levels will be moderate to high over the week with pollen levels lowest during cloudy and wet weather and highest during any sunny & dry periods. The main type of pollen will be grass this week.

Pollen levels could increase to very high this weekend in places

Dust forecast

Dust levels will be low across Ireland during week 1.

Week 2 - Monday 28th June 2021 -Monday 05th July 2021

Mean sea level pressure: Weekly mean anomalies

The outlook for next week (week2) is for a area of high pressure to sit across Ireland with the center of the high sitting just to the northwest of and west of Ireland. This would open the doors to drier and warmer weather.

Precipitation ( Rainfall): Weekly mean anomalies

Below average rainfall amounts are expected next week across Ireland around 30% to 60% below average

2m temperature: Weekly mean anomalies

The trend on weather forecast models including the long range ECMWF model which is used for this forecast shows above average temperatures for the time of year across Ireland next week (week 2) Temperature may rise into the mid to high 20s in places.

Wind Forecast

There are no signs of any strong winds during week 2

UV forecast

UV levels will be very high in any sunshine with the risk of sun burn.

Pollen Forecast

Pollen levels will be high to to very high over the week with pollen levels lowest during cloudy and wet weather and highest during any sunny dry periods. Grass pollen will be the main type.

Week 3 - Monday 5th July 2021 -Monday 12th July 2021

Mean sea level pressure: Weekly mean anomalies

Confidence in this week is a littler lower and more uncertain but the latest extending long range forecast shows higher pressure sitting across Ireland or just to the west or northwest which would mean a southeasterly airflow.

Precipitation ( Rainfall): Weekly mean anomalies

Rainfall amounts are also currently forecast to be lower than average due to higher pressure sitting near or over Ireland.

2m temperature: Weekly mean anomalies

Air temperatures are also forecast to be just above average across Ireland with temperatures possibly in the low to mid 20s and possibly into the high teens in places under the right set up.

Wind forecast

There are no strong signals for windy conditions over week 3

UV forecast

UV levels will be High to very high in any sunshine with the risk of sun burn.

Pollen forecast

Pollen levels will be high to very high over the week with pollen levels lowest during cloudy and wet weather and highest during any sunny dry periods. Grass pollen will be the main type

Week 4 - Monday 12th July 2021 -Monday 19th July 2021

Mean sea level pressure: Weekly mean anomalies

And finally week 4 confidence is even lower as you can see from the above pressure chart attached but the latest signal is for higher pressure across Ireland bringing a further spell of settled & warmer weather.

Precipitation ( Rainfall): Weekly mean anomalies

Below average rainfall amounts are signaled for week 4 across Ireland with settled weather.

2m temperature: Weekly mean anomalies

Again confidence in this week is rather low but the latest long range forecast from the ECMWF model indicates temperatures near normal for this time of year in the low 20s possible into the mid to high 20s.

Wind forecast

No strong winds are signaled for this week

UV forecast

UV levels will be High to very high in any sunshine with the risk of sun burn even with cooler weather as the sun this time of year is stronger.

Pollen forecast

Pollen levels will be high to very high and possible very high over the week with pollen levels lowest during cloudy and wet weather and highest during any sunny dry periods. Grass pollen the main type