30 Day Ag Weather Outlook MD – VA – TN- NC – SC (Mon. Morning, March 13, 2017)
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Collapse ▲Good morning,
I am expecting to hear back this morning from growers who are presently assessing their Crop Status and Condition – you may wish to do this very quickly this morning before “precipitation events” begin later today (Monday). Having a good handle on Crop Status and Condition at this time is necessary to understanding how this Cold Event may impact your crop, and finally on Crop Protection Strategy. Last evening, we heard some discussion from one grower, Eric Hunter, Easley, SC, who has been “processing” recent changes in his forecast (possibility of 15 F minimum on Thur morning), and based on past experience with irrigation system freezing up at such low temps, his decision may now be to not attempt sprinkling on covers.
I have had an experience with a main line that froze up at Clayton Central Crops during a windborne freeze with temperatures in the teens, and we were unable to get the water running again after about 2 a.m. Thank goodness we had a single layer of row covers on the crop, and we managed to save our emerged tight buds, but everything else got zapped! Back in those years (early 90s), this whole idea of sprinkling on row covers for windborne freeze conditions was just being tried for the first time (by us). I have seen growers have success (keeping open blossoms alive), with this approach with temperatures into the teens, but the sprinkling must remain continuous! You also must have a digital thermometer with thermocouples (at least 5) inserted into individual blooms beneath the covers to monitor “the patient’s” temperature. If blossoms are going below 31 F, you are beginning to enter a critical moment. If they go below 28 F for perhaps just a matter of 10-12 minutes, they’re dead! The good news is that those tight flower buds are much tougher, and it was a pleasant surprise for me to see that this stage had survived despite “losing our irrigation at 2 a.m.” on that fateful night – the covers that had become an “igloo” of ice did trap some ground heat, and kept that stage alive. One last point, it is a well known fact that fruit crops can do some amount of super-cooling in sub-freezing conditions if they are DRY. There is not a lot of good data on this phenomenon in strawberry, but I am well aware of its importance in grapes, and I have discussed super-cooling in grapes in this paper cold protection in winegrapes. What it amounts to is that if you have DRY ROW COVERS going into the BIG DADDY freeze nights (Wed/Thur & Thur/Fri), and NOT WET OR FREEZING UP, it could mean that your strawberry reproductive tissues (green fruit, open blossoms, popcorns and emerged tight buds), may be able to drop below what we normally assume to be the critical temperature of that plant part by perhaps 2 F. But, you cannot take advantage of super-cooling if those plant tissues become frozen up, and I have seen situations where soaking rains just before a deep-freeze event have resulted in plants becoming frozen into the covers, and there can be no doubt that the benefits of having a row cover are seriously compromised when this happens. Over the last week or so, I have had a number of new growers and extension agents contacting me, and there is no doubt that all of this is quite overwhelming! One new grower in the western piedmont of NC purchased an irrigation for his 3 acres of strawberries, but does not have a row cover. Given the kind of weather we’ll be experiencing in the week ahead, I think it is fair to say that an irrigation system by itself is not going to be a satisfactory approach, especially for a grower with no prior experience in running a sprinkler system under such dire conditions as these. Basically, we are now looking at a weather system that is every bit as dangerous as Easter freeze of 2007. Perhaps you have heard it said about sprinkler systems that in windborne freeze conditions (sub-freezing temps and winds of 10 mph, or greater), you are better off doing nothing at all. That is a very true statement. If you are running a sprinkler system that doesn’t have the capacity to handle high winds, incredibly low dew points and temperatures in the teens, your crop will “do better” if you don’t run at all. However, if you can get your hands on a row cover at this last minute, that would be an excellent option, and would allow you a chance of saving those emerged tight flower buds. TWO COVERS would be even better!
Fig. 1. Having a reliable irrigation system + row covers, is your best shot at protecting the entire crop (all the stages) in the kinds of conditions we’ll likely be seeing this Wed/Thur and Thur/Fri – this is an inspiring photo from a young new grower up in Southern NJ who is using the row cover + sprinkling approach in some very very tough conditions up there.
| 1. Crop status | (3/13) | By Variety | Crop Condition? | Damage? | By Variety | |
|
Open blossom? Popcorn Tight buds |
What is remaining? |
Open blossom? Popcorn Tight buds |
||||
| 2. Cold event | Min temp 3/16 (Thur) | Wind speeds? | Wet covers? | Frozen covers? | ||
| 3. Crop protection? | Irrigation alone | Row cover alone | H20 + Row Cover | |||
| What actual approach, or approaches will you use? | -only works to about 7-8 mph winds; big concern evaporative cooling and freezing up | Double covers? if dry can be very effective | – need sprinkling to be uniform and continuous |
30 Day Ag Weather Outlook MD – VA – TN- NC – SC
We have updated the online 30 day forecast below – sorry for slight delay in getting this out. Even though our forecast badly missed the timing of the very cold outbreak this past weekend, we think weunderstand what is behind the current very complex weather pattern and why the forecast models are having such a hard time with the forecasts even a few days out. We think the basic problems with the model forecast are caused by:
(1) The fact that there is a very strong (stronger than usual) thermal gradient from north to south across North America (see the new “items of interest” graphic at the bottom of this advisory). Thus small changes in the wind pattern can rapidly evolve to large difference in the thermal pattern across the US.
(2) The northeastern Pacific and northwestern Atlantic sea surface temperatures patterns favor northern hemispheric atmospheric thermal and jet stream patterns that tend to cause cold weather systems to drop out of Canada into the southeastern US. Over time the sea surface temperatures used by the forecasts models tend to resemble climatology which cause the model to lose the forcing that creates the cold weather pattern in the eastern US.
The following are our forecast trends and reasoning for the next month.
The upcoming week will be another very cold and active weather period. There is reasonable weather forecasts model agreement until about Mar 20. After a week, the the forecast models tend to diverge in their forecast solutions and vary from run-to-run even for the same forecast model. So after March 20 the US, Canadian and European models all show somewhat different forecasts. So after March 20 there is condsiderable uncertainty in the details of the forecasts in terms of timing of systems. However the atmospheric forcing resulting from El Nino-La Nina-Sea Surface Temperature patterns and the North American snowpack – atmospheric thermal pattern strongly indicate conditions will generally favor below normal temperatures with above normal precipitation.
On the longer term, the seasonal forecasts continue to be uncertain because some large scale forcing factors favor above normal temperatures conditions and some favor below normal temperatures in the eastern US. The ENSO cycle remains near neutral, but seems to be slowly switching from weak La Nina to weak El Nino conditions. Features of both a typical La Nina and El Nino are still evident in the tropical and global patterns.
Trying to balance all the factors, our best estimate is that the April to May time frame will tend to see more seasonal temperatures and drier conditions from the mid Atlantic to southeast US. We will make a comprehensive analysis of the long term factors and trends over the next week and update the seasonal outlook in next week’s forecasts.
Forecast discussion day 3 – 5 (15 Mar – 17 Mar) Temperatures very cold, well below normal; scattered snow showers early in the period. To start the period, a strong “nor’easter” will be moving into the Canadian Maritimes causing a strong northwest wind flow in the eastern US. At the same time a very large cold “arctic” high pressure system will be slowly moving southeast out of central Canada into the region. This will result in very cold temperatures, in the range of 15 – 30 F below the seasonal average, from early to late in the period and only warming to 8 – 12 degrees below normal by late in the period. Expect the period to be mostly dry with only the chance of some widely scattered snow showers in the eastern half of the forecast region very early in the period. Expect high temperatures to range from the upper 20s in the far north of the region to the upper 40s in the southern sections of the region early to mid-period. Expect low temperatures to range from the low 10s to mid 20s. Expect temperatures to warm about 10 degrees by late in the period. Precipitation amounts will likely be light in the 0.00 – 0.10” range.
Forecast discussion day 6 – 8: (18 Mar – 20 Mar) Temperatures remain below normal; scattered rain/snow early to mid-period then rain western section late in the period. Expect the cold high pressure system from the last period to remain across the region during this period keeping temperatures 5 – 10 F below normal. Also expect two weak frontal systems to move through the high pressure from west to east bringing rain and snow showers early and rain showers late in the period. Expect high temperatures to range from the mid 30s in the north to low 50s in the south. Low temperatures ranging from the upper 30s to mid 20s. Precipitation amounts will likely in the 0.30 – 0.50” range.
Forecast discussion day 9 – 11: (21 Mar – 23 Mar) Temperatures cool to back to well below normal; rain showers and scattered thunderstorms likely early to mid period. A cold front will movie through the region from the northeast to southeast followed by another strong cold high pressure system, once again bringing the temperatures well below normal. The cold front will likely bring showers and scattered thunderstorms to the region. Expect high temperatures to range from the mid 30s in the north to low 50s in the south. Low temperatures ranging from the upper 30s to low 20s. Precipitation amounts will likely in the 0.15 – 035” range” range.
Forecast discussion day 12 – 14: (24 Mar – 26 Mar) Temperatures warm to slightly below normal; Wide spread rain (snow in the higher elevations) early to mid period. It is still very early for details, but expect the possibility of a strong low pressure system to form in the upper Mid West US and move east through region over the period. Expect periods of wide spread rain with snow in the higher elevations during the forecast look ahead period. Expect high temperatures to range from the low 40s to low 60s. Low temperatures ranging from the upper 20s to low 30s. Precipitation amounts will likely in the 0.15 – 035” range.
Day 15 – 30 Temperature Outlook 1 Apr – 16 Apr
Day 15 – 30 Precipitation Outlook 1 Apr – 16 Apr
| Outlook discussion day 15 – 22: (27 Mar – 3 Apr) Early indications are that temperatures will be below the seasonal average and precipitation above the seasonal average during this period. | Outlook discussion day 23 – 30: (4 Apr – 11 Apr) Early indications are that temperatures and precipitation will be near the seasonal average during this period. |
| General Seasonal Outlook Mar – May 2017 | |
| Expect the forecast region to be generally warmer and wetter than normal for the period Mar – May 2017. The storm track and position of the semi-permanent Atlantic high pressure system will promote warm and moist southerly flow from the Southeastern states into the Mid-Atlantic states during the period. With abundant moisture and expected precipitation, expect that there will be a tendency for the minimum temperatures to be well above normal and the high temperature averaging only slightly above normal. |
MD
10-DAY DETAILED HOURLY WEATHER FORECASTS
VA
10-DAY DETAILED HOURLY WEATHER FORECASTS
NC
10-DAY DETAILED HOURLY WEATHER FORECASTS
SC
10-DAY DETAILED HOURLY WEATHER FORECASTS
GA
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KY
10-DAY DETAILED HOURLY WEATHER FORECASTS
Special State Frost/Freeze Forecasts
AWIS Weather Services, Inc. North Carolina Frost/Freeze Forecast Produced at 504 a.m. CDT on Mon Mar 13 2017 ... Forecast for Tonight ... Northeast NC Coast Currituck/Camden/Pasquotank/Tyrrell Counties *** No Frost And/Or Freeze Danger Tonight *** Lowest Temperatures: 41 - 47 Elizabeth_City Min 45 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) 03/15/17 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 -------- -------- -------- -------- -------- -------- 29 - 35 24 - 31 23 - 32 37 - 43 39 - 46 38 - 45 -------- East Central/SE NC Coast Carteret/Pamlico Counties *** No Frost And/Or Freeze Danger Tonight *** Lowest Temperatures: 46 - 50 Morehead_City Min 46 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) 03/15/17 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 -------- -------- -------- -------- -------- -------- 29 - 34 25 - 28 22 - 30 30 - 39 40 - 44 45 - 46 -------- Southeast NC NWS FORECAST ZONES 87-90,96-101 **** LITTLE IF ANY FROST DUE TO CLOUDS/WIND **** Lowest Temperatures: 39 - 47 Elizabethtown Min 42 Range Dewpoint Temps: 34 - 50 Range Wetbulb Temps: 37 - 50 AVG Wind Direction/Speed: NW 11 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) 03/15/17 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 -------- -------- -------- -------- -------- -------- 25 - 31 21 - 27 23 - 30 29 - 41 39 - 43 43 - 49 -------- North-Central NC Franklin County Area **** FREEZE COLD LOCATIONS **** **** LITTLE IF ANY FROST DUE TO CLOUDS **** Lowest Temperatures: 31 - 42 Louisburg Min 31 Durations at/below 32: 0 - 3 Range Dewpoint Temps: 21 - 32 Range Wetbulb Temps: 32 - 37 AVG Wind Direction/Speed: NW 8 AVG Sky Condition: 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) 03/15/17 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 -------- -------- -------- -------- -------- -------- 20 - 29 17 - 24 20 - 27 30 - 37 34 - 41 37 - 44 -------- North/Central NC Alamance County Area **** NEAR FREEZING COLD LOCATIONS **** **** LITTLE IF ANY FROST **** Lowest Temperatures: 33 - 38 Graham_AG Min 35 Range Dewpoint Temps: 20 - 32 Range Wetbulb Temps: 32 - 37 AVG Wind Direction/Speed: NW 7 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) 03/15/17 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 -------- -------- -------- -------- -------- -------- 21 - 26 18 - 23 21 - 26 25 - 37 36 - 41 39 - 44 -------- South/Central NC Richmond County Area **** NEAR FREEZING COLD LOCATIONS **** **** LITTLE IF ANY FROST **** Lowest Temperatures: 34 - 41 Ellerbe Min 41 Range Dewpoint Temps: 25 - 39 Range Wetbulb Temps: 34 - 40 AVG Wind Direction/Speed: NW 8 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) 03/15/17 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 -------- -------- -------- -------- -------- -------- 23 - 29 21 - 26 24 - 29 37 - 39 38 - 41 43 - 46 -------- Interior/EC-SE NC Wayne County Area **** LITTLE IF ANY FROST DUE TO CLOUDS/WIND **** Lowest Temperatures: 39 - 44 Goldsboro_AG Min 43 Range Dewpoint Temps: 39 - 44 Range Wetbulb Temps: 40 - 44 AVG Wind Direction/Speed: NW 10 AVG Sky Condition: 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) 03/15/17 03/16/17 03/17/17 03/18/17 03/19/17 03/20/17 -------- -------- -------- -------- -------- -------- 27 - 30 22 - 25 25 - 28 29 - 38 38 - 42 41 - 44 -------- For more detailed information visit www.awis.com or call 888-798-9955. Copyright 2017 AWIS Weather Services, Inc. All rights reserved.