Final Multi-State Freeze Alert for Tuesday (4:50pm, 3/14/17)
go.ncsu.edu/readext?453967
Good late afternoon,
I realize this has been “a lot” to deal with in terms of figuring out a good strategy for tonight and the next few nights. What I would like to say is that you already have some pretty good (not perfect) tools at your disposal for managing windborne freezes (like tonight), like a row cover! My great concern is that sprinkling alone tonight could result in a real calamity. It still doesn’t look like such a great option for Wed/Thur, but let’s just see what the forecast brings tomorrow? The opportunity to use sprinkling could be better with tomorrow’s forecast for Wed/Thur.
What we are likely going to see tomorrow is a black frost (Wed/Thur), and the combination of a row cover and sprinkling is terrific for this situation! It works! And, so will a double cover for areas like Eric Hunter’s in Easley, SC, that may drop into upper teens. When winds finally do die down in the morning on Thursday, it may even be worth running the drip system from perhaps 3:30 a.m. to sunrise, to add a few precious degrees. Like I said earlier, I’m pretty good with relying on double covers for protection down to 20 F, but below that temperature I am not sure?
To finish out this particular go round of cold protection for this week, it looks like we may have a hybrid of a white frost and black frost on Thur/Fri, and for this sort of event, growers have more flexibility in terms of control options. I think irrigation alone will handle this one. I also think row covers will work fine. I am doubtful we will need both row covers and sprinkling.
The trick is to not over react conditions tonight. If you do not sprinkle on top of your crop tonight, you can still take advantage of super-cooling (by doing nothing). This is a pretty amazing plant process that works best in dry air conditions (like today and tonight) and where the temperature is dropping gradually (1-2 degrees per hour). It is a process that can allow a blossom to survive air temperatures that are even slightly below 28 F. I still remember the excitement of a Georgia grower some years ago who placed a max/min thermometer in his field, and discovered the minimum at canopy level got to 27 F, and he thought for sure he lost everything. He didn’t! He had plans to irrigate that night, but ended up doing nothing because of an irrigation system issue. He actually had excellent blossom survival. In the end, I think experience is the most important factor of all in being able to come up with a successful at cold protection program for a very difficult week like this one. Since the last time we saw an event as serious as this one (Easter Freeze 2007), we have gained a lot of new understanding and experience in managing these kinds of events. I can assure you, losing a lot of crop has a way of being a good teacher! And, the thing that I have noted in the last few days from grower texts and emails, is how healthy an appreciation our industry has gained for the “downside” of using any sprinkling in a windborne freeze event LIKE TONIGHT. This is not a silver bullet. And, that is why many of you are calling, texting and emailing questions about using DRIP in conjunction with covers for this event tonight and tomorrow morning. The problem I see with this is a very limited base of experience. I think it has potential to work very well under lower wind conditions, but it is an untested technology for windborne freezes? And, I continue to hear concerns about systems freezing up. We are definitely short of on time now for coming up with any NEW solutions. But, at the bottom of the advisory I have added some recent thoughts of Tom Baker over in VA Beach regarding drip under covers.
Double-checking your forecast one last time:
For tonight (Windborne FREEZE – Tue/Wed): Let me cut to the chase — > be cautious in testing new, untested approaches. In addition, be very careful in using very old technologies, like sprinkler irrigation (around since the 1950s for strawberry frost protection), in radically different weather conditions, like the ones we are now experiencing.
Take a moment NOW to really study wet bulb temps for all through the night, because this is the temperature your strawberry plants will soon feel if they are encased in ice, and no new water is applied. I can almost guarantee you will lose most of the open blooms and popcorns if you cannot resume sprinkling within about an hour (assuming you have a row cover), and if there is no row cover, major damage occurs within minutes. Thus, the old saying, “you are better off doing nothing (re: sprinkling alone), in a windborne freeze condition,” is still a very good one in my opinion.
6:19 p.m. –NC Grower Question about using sprinkling in area of state with winds above 10 mph tonight and will have wet bulb of less than 33 F for 43 hours – open this document to read more
MD
10-DAY DETAILED HOURLY WEATHER FORECASTS
VA
10-DAY DETAILED HOURLY WEATHER FORECASTS
AWIS Weather Services, Inc. North Carolina Frost/Freeze Forecast Produced at 306 p.m. CDT on Tue Mar 14 2017 ... Forecast for Tonight ... Northeast NC Coast Currituck/Camden/Pasquotank/Tyrrell Counties **** FREEZING TEMPERATURES **** **** LITTLE IF ANY FROST DUE TO CLOUDS/WIND **** Lowest Temperatures: 26 - 32 Elizabeth_City Min 26 Durations at/below 32: 1 - 10 Durations at/below 28: 0 - 4 Range Dewpoint Temps: 16 - 36 Range Wetbulb Temps: 25 - 41 AVG Wind Direction/Speed: NW 14 AVG Sky Condition: Mostly Cloudy Extended Forecast: Range of Lowest Min Temperatures in the Above Zones Min Temps Valid For Morning of Given Date (May NOT include ALL cold pockets) 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 03/21/17 -------- -------- -------- -------- -------- -------- 22 - 30 28 - 34 42 - 48 39 - 45 35 - 41 43 - 49 -------- East Central/SE NC Coast Carteret/Pamlico Counties **** FREEZING TEMPERATURES **** **** LITTLE IF ANY FROST DUE TO CLOUDS/WIND **** Lowest Temperatures: 30 - 31 Morehead_City Min 30 Durations at/below 32: 2 - 4 Range Dewpoint Temps: 20 - 35 Range Wetbulb Temps: 28 - 41 AVG Wind Direction/Speed: NW 15 AVG Sky Condition: Mostly Cloudy Extended Forecast: Range of Lowest Min Temperatures in the Above Zones Min Temps Valid For Morning of Given Date (May NOT include ALL cold pockets) 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 03/21/17 -------- -------- -------- -------- -------- -------- 22 - 27 28 - 31 44 - 46 39 - 42 34 - 39 40 - 46 -------- Southeast NC NWS FORECAST ZONES 87-90,96-101 **** HARD FREEZE **** **** LITTLE IF ANY FROST DUE TO CLOUDS/WIND **** Lowest Temperatures: 25 - 30 Elizabethtown Min 28 Durations at/below 32: 4 - 9 Durations at/below 28: 0 - 4 Range Dewpoint Temps: 14 - 37 Range Wetbulb Temps: 24 - 40 AVG Wind Direction/Speed: NW 14 AVG Sky Condition: Partly Cloudy Extended Forecast: Range of Lowest Min Temperatures in the Above Zones Min Temps Valid For Morning of Given Date (May NOT include ALL cold pockets) 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 03/21/17 -------- -------- -------- -------- -------- -------- 22 - 26 25 - 29 42 - 47 36 - 42 33 - 39 42 - 49 -------- North-Central NC Franklin County Area **** HARD FREEZE **** **** LITTLE IF ANY FROST DUE TO WIND **** Lowest Temperatures: 16 - 27 Louisburg Min 16 Durations at/below 32: 7 - 15 Durations at/below 28: 2 - 13 Range Dewpoint Temps: 7 - 25 Range Wetbulb Temps: 17 - 33 AVG Wind Direction/Speed: NW 12 AVG Sky Condition: Partly Cloudy Extended Forecast: Range of Lowest Min Temperatures in the Above Zones Min Temps Valid For Morning of Given Date (May NOT include ALL cold pockets) 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 03/21/17 -------- -------- -------- -------- -------- -------- 17 - 23 21 - 28 41 - 47 32 - 39 27 - 35 40 - 47 -------- North/Central NC Alamance County Area **** HARD FREEZE **** **** LITTLE IF ANY FROST DUE TO WIND **** Lowest Temperatures: 18 - 23 Graham_AG Min 20 Durations at/below 32: 12 - 15 Durations at/below 28: 7 - 12 Range Dewpoint Temps: 5 - 25 Range Wetbulb Temps: 18 - 33 AVG Wind Direction/Speed: NW 12 AVG Sky Condition: Partly Cloudy Extended Forecast: Range of Lowest Min Temperatures in the Above Zones Min Temps Valid For Morning of Given Date (May NOT include ALL cold pockets) 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 03/21/17 -------- -------- -------- -------- -------- -------- 18 - 23 22 - 27 42 - 47 33 - 38 29 - 34 42 - 46 -------- South/Central NC Richmond County Area **** HARD FREEZE **** **** LITTLE IF ANY FROST DUE TO WIND **** Lowest Temperatures: 22 - 27 Ellerbe Min 27 Durations at/below 32: 7 - 12 Durations at/below 28: 1 - 8 Range Dewpoint Temps: 8 - 31 Range Wetbulb Temps: 21 - 38 AVG Wind Direction/Speed: NW 13 AVG Sky Condition: Partly Cloudy Extended Forecast: Range of Lowest Min Temperatures in the Above Zones Min Temps Valid For Morning of Given Date (May NOT include ALL cold pockets) 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 03/21/17 -------- -------- -------- -------- -------- -------- 20 - 25 25 - 28 42 - 44 34 - 39 33 - 37 45 - 47 -------- Interior/EC-SE NC Wayne County Area **** HARD FREEZE **** **** LITTLE IF ANY FROST DUE TO WIND **** Lowest Temperatures: 25 - 28 Goldsboro_AG Min 27 Durations at/below 32: 5 - 9 Durations at/below 28: 1 - 4 Range Dewpoint Temps: 17 - 32 Range Wetbulb Temps: 25 - 37 AVG Wind Direction/Speed: NW 13 AVG Sky Condition: Partly Cloudy Extended Forecast: Range of Lowest Min Temperatures in the Above Zones Min Temps Valid For Morning of Given Date (May NOT include ALL cold pockets) 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 03/21/17 -------- -------- -------- -------- -------- -------- 22 - 24 26 - 28 41 - 46 37 - 40 32 - 36 41 - 46 -------- For more detailed information visit www.awis.com or call 888-798-9955. Copyright 2017 AWIS Weather Services, Inc. All rights reserved.
10-DAY DETAILED HOURLY WEATHER FORECASTS
SC
10-DAY DETAILED HOURLY WEATHER FORECASTS
GA
10-DAY DETAILED HOURLY WEATHER FORECASTS
KY
10-DAY DETAILED HOURLY WEATHER FORECASTS
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An hour ago, Tom Baker sent an email (below), in which he says,
I think we need a little more than covers alone and think drip is the way to go but I’m concerned about drip system freeze-up (residual water in the skinny drip tapes, drip line valves, even larger hoses and valves—all exposed to the (cold) air and radiant “heat” exchange with cold outer space on few- and no-cloud Wed and Thurs nights). Our drip head hoses, line valves, and 12-18 inches of drip lines are NOT under our row covers.
My plan is to check our systems, zip tie a couple of thermocouple wires to the drip valves (“lowest” and most exposed point in our system) to read “right-there” temp. We’ll turn on drip when temp at valves reads 33 or so.
I’m thinking that running/flowing water will surely not freeze, even if temp drops to 22 as AWIS predicts? If it does, any growers using this strategy would be in deep doo-doo.
This might run more water than would be needed if turn-on time is determined by blossom temps, but would hopefully guarantee no drip line or drip valve freeze up. What would “extra” hours of running the drip hurt??? More leaching of fertilizer, no doubt. But a little extra fertilizer (when the weather improves) is far cheaper than potential blossom losses that could arise from covers that might still be damp, combined with high winds and low temps.
Even if that one outlying AWIS of 22 happens, I think we will still be safe!
Just my thoughts.
Tom