Upcoming pattern change signals trend to warmer drier weather for the Prairies

Our cool and wet September is drawing to a close, but it looks like some warmer and drier weather will finally be moving in for the last few days of the month. A persistent storm track over the northern US has brought several significant rainfall events over southern Manitoba over the past 4 weeks, with 100-250 mm of rain across the Red River valley during that time. The suppressed jet stream has also maintained cooler than normal temperatures through the period with only 2 days reaching the 20C mark in Winnipeg this month. But a long awaited pattern change is finally beginning this weekend, and long range models are suggesting drier and warmer than normal conditions will persist across the Prairies through the first week of October. (see 6-10 day outlook from CPC)

In the short term, early morning cloud and fog patches will give way to sunshine and pleasant temperatures today, with afternoon highs in the mid to upper teens along with light winds. Even warmer conditions are expected Sunday as gusty south winds to 60 km/h push temperatures into the low to mid 20s across southern MB, possibly the warmest day of the month so far. A weak cold front will pass through Monday with a slight chance of showers, followed by sunny skies and 20C temperatures Tuesday. Dry but slightly cooler weather is expected for the end of the week as high pressure builds over the eastern Prairies. Long range models continue to indicate the development of a large upper ridge over the Prairies during the first week of October, bringing a spell of warm and dry weather to southern Manitoba to start the new month. Here's hoping to warmer and drier weather in October!

Another soaking rain for the Red River valley

Southern Manitoba once again received more rain Thursday night on already saturated grounds. A storm system moving through the Dakotas brought rainfall amounts of 20 to 50 mm over the Red River Valley Thursday through Thursday night with over 60 mm falling over extreme southeastern Manitoba.

Here is a summary of some of the more significant rainfall amounts reported over the last 24 hours as of 8 AM Friday morning.

Winnipeg (airport) .. 19.0 mm
Winnipeg (Forks) .... 17.6 mm
Winnipeg (St. Vital)... 25.4 mm
Winnipeg (Chwd) ...... 22.6 mm /Rob's Obs/
Dugald .............. 36.4 mm
Letellier ........... 37.0 mm
St. Pierre .......... 50.4 mm
Morris .............. 48.2 mm
Steinbach ........... 38.8 mm
Gretna .............. 27.8 mm
Emerson ............. 38.0 mm
Starbuck ............ 20.4 mm
Winkler ............. 33.6 mm
Vassar .............. 51.5 mm
Piney ............... 55.4 mm
Sprague ............. 63.0 mm

24C by Sunday? Could it be?

Long range models continue to indicate an upcoming change this weekend in the below normal weather pattern that has plagued the Prairies most of September. A large upper ridge is forecast to build over western North America by the weekend that will send a surge of warm air across Alberta and Saskatchewan beginning Saturday. Low pressure crossing the northern Prairies will push this warmth eastward over southern Manitoba on Sunday with temperatures expected to climb into the low to mid 20s.. potentially the warmest day of the month so far that has seen only 2 days reach the 20C mark in Winnipeg, with a maximum of only 22C on the 1st. Current forecasts suggest 24C temperatures continuing Monday in Winnipeg however, model guidance is indicating a brief cooldown Monday and Tuesday before another surge of warm air moves in for the middle and end of next week. All in all, it looks like we may finally be seeing some above normal temperatures to end what has been a generally cool September.

2010 growing season ends for Winnipeg and northern RRV

A ridge of high pressure brought clear skies and light winds last night to Winnipeg and the northern Red River valley, allowing widespread frost to form early this morning. Temperatures dipped to a low of -1.5C at Winnipeg airport, officially ending the 2010 growing season for the city. Using airport data, this year's growing season was 132 days , 11 days longer than average, and 18 days longer than 2009. This was due to a fairly early start to the growing season this year with the last spring frost recorded on May 9th at the airport.. some 2 weeks ahead of the normal last frost. At Winnipeg airport, the average growing season is about 121 days between an average last spring frost on May 23rd, and a first fall frost on Sept 22nd. Last year, the airport had a 114 day growing season (Jun 7th - Sept 28th), shortened due to a late spring frost in June.

Elsewhere across the Red River valley, most areas north of Highway 3 had frost this morning with overnight lows of 0 to -2C. The southern valley however escaped frost due to cloud cover that spread along the US border. Areas from Morris southward generally stayed above freezing last night.

Increasing cloud cover and moderating temperatures will prevent the threat of frost over the next few days. In fact, long range models are hinting of above normal temperatures moving in for next weekend into the last week of September with temperatures of 20-25C possible. Here's hoping!

Frost likely tonight across Red River valley

Winnipeg and the Red River valley were spared from frost last night due to a steady westerly wind that kept temperatures above zero. Tonight however, winds are expected to be light as a ridge of high pressure builds into southern MB. That ridge brought a hard freeze to much of southern SK and Alberta last night with overnight lows of -2 to -7C. Clear skies and light winds in the ridge allowed for maximum radiational heat loss from the surface, resulting in the frosty temperatures. Overnight lows aren't expected to be quite as cold tonight over southern MB as temperatures moderate somewhat today and some high level cloud moves in tonight, however widespread readings of 0 to -2C are likely by early Sunday morning across the Red River valley including Winnipeg (except downtown which should remain above zero due to the urban heat island effect). The southern Red River valley may also be spared from frost with some thicker cloud cover spreading in from Montana. Overall though it looks like the growing season will officially come to an end Sunday morning in Winnipeg, a good 10 days earlier than last year (first frost last year at Winnipeg airport was on September 29th with a minimum of -2.4C during the city's warmest September on record)

Fall arriving early..

The official first day of fall is next Wednesday Sept 22nd.. but Mother Nature will be bringing in fall like weather a little early this year, as a sharp cold front pushes through southern Manitoba Thursday night. This front will usher in an unseasonably cool airmass from the northern Prairies Friday into the weekend, with temperatures only rising into the low teens along with brisk west to northwest winds. There's even a chance of some snow over northern Manitoba by Saturday as a low pressure system intensifies over the north. High pressure building in by Sunday morning will bring a good chance of widespread frost early Sunday across southern MB. Cool conditions are expected to persist into early next week along with an increasing threat of showers.

Early season snowstorm Sept 12-13 1903

Yes, fall's come early this year.. but it could be worse. On this date in 1903, an early season snowstorm left 10 to 30 cm of wet snow across western Manitoba. The image on the left shows a shot of Birtle MB near the SK border on Sept 13 1903 (image from Brock Holowachuk's book "Impact - A History of Disasters in Manitoba")

Elevation usually plays a major role in early season snowstorms and this one was no exception. Precipitation from this system fell mainly as rain in the Red River valley with 39 mm of rain recorded in Winnipeg and a high of only +9C. Further west however, rain changed to snow over higher elevations west of the Pembina escarpment with the highest amounts over southwestern MB. Snowfall amounts over western MB included..

Hillview .............. 30 cm (between Brandon and Virden)
Rapid City........... 25 cm
Deloraine............. 23 cm
Turtle Mtn ......... 20 cm
Minnedosa ......... 15 cm
Elkhorn ............... 15 cm
Dauphin .............. 15 cm
Brandon .............. 10 cm

Eastern Saskatchewan reports:

Moosomin...........  38 cm
Manor ...............  23 cm (near Carlyle)
Alameda ............. 15 cm (near Oxbow)
Crescent Lake ..... 15 cm (near Yorkton)

The heavy snow and high winds wreaked havoc on crops and infrastructure with heavy losses reported in the wheat crop and numerous telegraph poles downed.  So as cool and wet as it's been this September, it has been worse!

Dry most of the week.. cool outbreak looms for weekend..

A nice looking Sunday is on tap today with mostly sunny skies, a westerly breeze and temperatures close to 20C this afternoon. Cooler weather is expected Monday as northwest winds draw in cooler air from the west, with a risk of patchy frost over southern MB Tuesday morning. Dry weather is expected to continue through through mid week although a storm system moving through Dakotas on Wednesday threatens some rain near the US border. (models currently indicate this system should remain south of the border but we'll keep our eye on any changes) By Friday, a low pressure system tracking across the eastern Prairies will usher in a colder airmass for the weekend, with highs only in the low teens expected along with an increasing potential for frost. Looks like fall is coming early this year..

Another day.. another 25-50 mm..

The third significant rainfall event in the past 12 days has dumped another 25-50 mm of rain over the Red River valley.. boosting totals since Aug 30th into the 100-175 mm range (4-7 inches) This is an abnormally large amount of rain for this time of year, with average September rainfall around 52 mm for the month. The wet weather has ensured the already waterlogged soil conditions remain saturated across the Red River valley, with extensive standing water in fields and ditches making for difficult harvesting conditions this year.

Some rainfall totals over the past 24 hours.. and since Aug 30th.

Winnipeg airport.... 22 mm .... 94 mm since Aug 30
Winnipeg Forks...... 30 mm* .... 108 mm* (estimated)
Winnipeg Chwd...... 35 mm ..... 125 mm /Rob's Obs/
Winnipeg city rainfall maps:
Aug 30-31 / Sept 1-2 / Sept 9-10

Morris...................... 39 mm .... 176 mm
Carman ................... 34 mm .... 128 mm
Elm Creek .............. 27 mm ...... 93 mm
Manitou .................. 47 mm ..... 118 mm
Starbuck.................. 32 mm ..... 95 mm
Dugald..................... 31 mm ..... 120 mm
Letellier.................. 25 mm ..... 113 mm
St Pierre ............... 25 mm ...... 106 mm
Steinbach ............. 27 mm ...... 100 mm
Selkirk ................. 26 mm ........ 86 mm
Teulon ................. 39 mm ........ 105 mm
Woodlands .......... 28 mm ........ 121 mm

NOTE: above data from Manitoba Agriculture Network

The good news is that the heavy rainfall events appear to be over for awhile.. at least through the next week or so as we get into a drier but cool pattern. Unfortunately, limited sunshine and below normal temperatures will make it difficult to get rid of standing water quickly.. which will increase the liklihood of going into the winter with saturated soil conditions.

Storm system threatens significant rainfall Friday

The next storm system coming off the Pacific ocean is forecast to intensify over the next 24 to 48 hours as it moves into the Dakotas and eastern Prairies by Friday. This system will tap an increasingly moist and unstable airmass over the US plains generating widespread showers and embedded thunderstorms as it moves eastward. Rain is expected to move into the Red River valley Thursday night and continue through Friday into Friday night before moving into NW Ontario. At this point, models are indicating a fairly good chance of seeing at least 25 mm of rain with this system over the Red River valley, with amounts of 50 mm possible in some areas. Ditches and fields remain waterlogged across the valley thanks to heavy rains over the past 10 days (100-150 mm).. and it's becoming increasingly difficult to dry up this ground moisture as we get into the fall with weaker sunshine and cooler weather. This next system will further delay chances of drying out appreciably before winter freezeup.

More rain on the way..

Not the news we want to hear, but another round of precipitation is on the way over the Red River valley later today into tonight with some scattered thunderstorms possible. Rain may be locally heavy at times with amounts of 15-25 mm possible mainly tonight into Thursday morning. The rain is unwelcome news after Monday's soaking which brought 40-100 mm of rain through the valley. As this system moves to the east Thursday, gusty north winds will develop with gusts to 60 or 70 km/h by afternoon and temperatures only in the mid teens.. definitely a fall like feel to the day. Things should start clearing out Friday with a nice looking weekend ahead with sunshine and moderating temperatures for Saturday and Sunday. The next weather system threatens showers by Monday or Tuesday of next week.