Final Multi-State Freeze Alert for Tuesday (4:50pm, 3/14/17)

— Written By Barclay Poling

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

winston que

MD

MD Temp Outlook

10-DAY DETAILED HOURLY WEATHER FORECASTS

Aberdeen Andrews_AFB Annapolis_Naval Baltimore_Sci_Ce
Baltimore/Wash Cambridge/Dorche College_Park_AP Cumberland_AP
Easton_MD Fort_Meade Frederick_MD Gaithersburg_AP
Hagerstown_AP Leonardtown Middle_River Oakland_MD_AP
Ocean_City_AP Patuxent_River Salisbury Stevensville_AP
St_Inigoes/Webst Washington_DC_AP Westminster_AP

VA

VA Temp Outlook

10-DAY DETAILED HOURLY WEATHER FORECASTS

Abingdon Ashland_VA Charlottesville Chesapeake-Ches
Culpeper Danville Dublin/New_Riv Emporia_VA
Farmville Fentress_Naval_A Fort_Belvoir/Da Fort_Eustis/Fel
Franklin/J_B_Ro Hillsville Hot_Springs/Ing Jonesville_AP
Langley_AFB Leesburg/Godfre Louisa-Louisa_C Lynchburg
Manassas_Muni(A Marion/Wythev Martinsville Mecklenburg/Bru
Melfa/Accomack Newport_News Norfolk_Hampton_ Norfolk_NAS
Norfolk_VA Oceana Orange_VA Petersburg_(AWO
Quantico Richlands_AP Richlands_VA Richmond
Richmond_Chester Roanoke Shannon_Arpt Stafford_AP_VA
Staunton-Shenan Suffolk-Suffolk Tappahannock_AP Virginia_Tech_A
Wakefield_AP Wallops_Island Warrenton_Fauqui Washington_Dulle
West_Point_VA Williamsburg_VA Winchester_Rgnl Wise/Lonesome_P

NC NC Temp Outlook

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

Ahoskie-Tri-Cou Albemarle_AP Andrews Asheboro
Asheville_Munic Beaufort-Michae Boone_NC Burlington-Burl
Cape_Hatteras_AG Chapel_Hill-Hor Charlotte Cherry_Point
Clinton_NC Concord_NC Currituck_NC Edenton-Northea
Elizabeth_City Elizabethtown_NC Erwin-Harnett_C Fayetteville_AP
Fort_Bragg/Simm Franklin/Macon_C Gastonia-Gaston Goldsboro_AFB
Goldsboro_NC Greensboro Greenville_AP_NC Hickory
Jacksonville Jacksonville_(A Jefferson_AP_NC Kenansville-Dup
Kill_Devil_Hills Kinston_AP Lexington-David Lincolnton_AP
Louisburg_NC Lumberton_AP_NC Mackall_AAF Manteo/Dare_Co
Maxton Mcalf_Bogue_Fiel Monroe_AP_NC Morganton-Morga
Mount_Airy-Moun New_Bern North_Wilkesbor Oxford_NC
Piney_Island_Bom Pope_AFB Raleigh-Durham Reidsville_AP
Roanoke_Rap_AP Roanoke_Rapids_R Rockingham_NC Rocky_Mount-Wils
Roxboro_AP Rutherfordton Salisbury-Rowan Sanford_NC
Shelby_AP_NC Smithfield_AP Southern_Pines Southport_NC
Statesville-Sta Tarboro_AP Wadesboro_AP Washington-Warr
Whiteville_NC Wilmington_AP_NC Winston-Salem

SC

10-DAY DETAILED HOURLY WEATHER FORECASTS

Aiken_AP Anderson_Co_Air Barnwell_AP Beaufort_Cnty_AP
Beaufort_SC Bennettsville_Je Camden_AP Charleston_Exec_
Charleston_Muni Cheraw_AP Chester_AP Clemson-Clemson
Columbia-Columb Columbia/McEnti Columbia_Metro Conway_AP
Darlington Florence_SC Georgetown_AP_SC Greenville_Donal
Greenville_Down Greenville-Spart Greenwood-Green Hartsville_AP
Hilton_Head_AP Kingstree_AP Lancaster-McWhir Laurens_AP
Manning_AP Marion_AP_SC Moncks_Corner_AP Mount_Pleasant_A
Myrtle_Beach Newberry_AP North_Myrtle_Be Orangeburg-Oran
Pickens_AP Rock_Hill Spartanburg_Down Summerville_AP
Sumter_AP Sumter_SC Walterboro_AP Winnsboro_AP

GA

10-DAY DETAILED HOURLY WEATHER FORECASTS

Albany_Municipa Alma/Bacon_Co Americus_AP Athens_Municipa
Atlanta/DeKalb Atlanta/Fulton Atlanta_Intl_Ar Atlanta_Paulding
Augusta/Bush_Fi Augusta_Daniel_F Bainbridge_GA Blakely_AP
Brunswick_GA Brunswick/Glync Canton_GA Carrollton_AP
Cartersville_AP Claxton_AP Columbus_GA Covington_GA_AP
Dalton-Dalton_M Douglas_Muni Dublin/WHBarron Fitzgerald_AP
Fort_Benning Ft_Stewart/Wrig Gainesville_AP_G Greensboro_GA
Homerville_AP Hunter_(AAF) Jesup_AP La_Grange
Lakeland Lawrenceville_AP Macon_AP Marietta
Marietta/Cobb Milledgeville_AP Moultrie_Muni_AP Newnan-Newnan_C
Peachtree_City Rome_GA Savannah Statesboro_GA
Swainsboro_AP Sylvania_AP_GA Thomaston_AP Thomasville_AP
Thomson_GA Tifton_AP Valdosta Valdosta/Moody
Vidalia Warner_Robins_A Washington_GA Washington_GA
Waycross_AP Winder_AP

KY

10-DAY DETAILED HOURLY WEATHER FORECASTS

Bowling_Green Covington Danville-Powell_ Fort_Campbell
Fort_Knox/Godma Frankfort_AP Glasgow_KY Henderson_City
Jackson_KY Lexington_KY London_Corbin Louisville_AP
Louisville/Bowm Middlesboro_AP Monticello_KY_AP Murray_AP
Owensboro_AP Paducah Richmond_Madison Somerset(AWOS)

——————

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