Freezing cold weather is on the table Friday night. It sounds bad but in terms of our areas climatology, it's very close to the statistical average for the first 32 degree low. A Freeze watch is in effect, more on that in just a bit.
Before I tackle the chill, I've been updating the dryness in the weather pattern regularly for the past 2 weeks. This graphic courtesy of the Iowa Mesonet, indicates that September in Iowa was the 109th driest of 130 years of record. That puts it roughly in the top 15% of all-time driest years. Illinois was not as bad coming at 89th driest thanks to spotty heavier rains in small pockets around the state.
Here's a larger perspective of the rankings for the contiguous United State.
Here are the actual rainfall totals for September 1st through October 6th. It's clear to see where the heavier pockets of rain were centered.
Here's the departures those rainfall numbers represent over that period of time.
The latest drought monitor now reveals widespread dryness from Minnesota southward through Iowa and Missouri. Extreme drought conditions have now expanded into Minneapolis and much of southern Minnesota and sections of NW Iowa. Only 36 percent of the Midwest is not considered at least abnormally dry.
That number is even lower in Iowa where 85 percent of the state's soil moisture is at least abnormally dry. 77 percent of the state is considered to be in moderate to severe drought.
For the past few days models had been hinting at the possibility of the western ridge breaking down in the NW U.S. long enough for better precipitation potential out in the 8-14 day period. That was tied to phasing of the long wave pattern between the northern and southern streams. Today separation exists with phasing off the table. That likely means more of the same when it comes to dry weather. Here's the 15 day rainfall departures forecast on the EURO ending October 21st.
The GFS is just as bad if not worse.
Here again at 500mb is the projected jet stream flow October 13th. See the massive ridge over the Pacific NW that is driving the northwest flow deprived of rain producing moisture. That is also a very chilly look!
Check out the cold air that's delivering October 14th
October 18th the GFS shows lows that look like this. Now that's what I would call a hard freeze. Hopefully later runs will ease up on the depth of the cold air.
For what its worth, these are the temperature departures nearing 20 below normal October 18th...forecast lows are much more typical of December 1st.
THE IMPENDING COLD AND WEEKEND
Over the past 24 hours a cold front cut a path across the region and what a change that has initiated. Cold breezy conditions are back with us ending a streak Friday in the Quad Cities and my southern counties of 7 consecutive 70 degree days. Temperatures at noon Friday will be in the upper 40s to low 50s, in some places 25 degrees colder that at the same time Thursday. A north wind of 10-18 will make things fresh, especially in the morning. Some scattered cumulus clouds are likely but overall partly to mostly sunny skies will prevail.
Friday night is the challenging part of the forecast as the ridge axis reaches the area. Skies will be clear and the air dry. The final piece of the puzzle as far as a freeze is concerned is tied to wind. If it stays light and variable the duration of the night, most areas have a good chance of reaching 32 or a bit lower. There is a chance of just enough mixing to keep readings in some areas more in that 32 to 34 degree range. Models have as much as a 10 degree variance from the mid 20s on the 3k NAM (the coldest) to the mid to upper 30s on the EURO (the warmest). Thus confidence is not high on just how cold it ultimately gets. As a result, instead of a freeze warning the NWS has gone with a freeze watch which I think is a good call. Hopefully the set up is clearer later Friday. For sure there will be frost.
The national blend of models shows this for lows early Saturday.
The official NWS forecast has this.
Whatever happens, the rest of Saturday will be sunny but crisp. A good pumpkin picking day. Highs will generally be in the mid to upper 50s. Sunday return flow initiates a warming trend that lasts into Wednesday of next week. Highs will go from the upper 60s Sunday and Monday into the 70s Tuesday and Wednesday. The next remote chance of showers comes next Tuesday night or Wednesday ahead of another shot of cold air. Amounts look meager.
I will leave you with this because it's fun to look at even though its far from accurate. It's the Thursday version of the EURO weeklies. The control shows this for snowfall between now and November 21st.
Isn't that special. Have a great weekend everybody and of course, roll weather...TS