Friday Morning Update for NC and Region (8:22am, Fri., 3/27/15)

— Written By Barclay Poling
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8:22 a.m. (brief statement about general situation)

Good morning!

In looking at my weather updates from AWIS, Skybit and AccuWeather Pro, I have noted that we are on track for a challenging weekend of weather, and I am hoping that many of you were able to get row covers back on before today’s rains? There may actually be potential for FROST tomorrow morning (Sat) in a number of areas in NC. However, the bigger concern is Sunday morning! 

revised-tableFig. 1. Minimum temperatures on Sunday morning (Fig 2) will easily be cold enough to damage open blossoms and popcorns, but with temperatures in mid-20s in so many areas, there could be serious injury to flower buds you see in photo next to pencil. These buds may tolerate temperatures as low as 20 F, but there is also potential for damage even at 25 F, especially for the larger (more developed) buds.

7daytemp.nc.4Fig. 2. This is the latest AWIS minimum temp map for Sunday morning. Unfortunately, this is much colder than what we were expecting on Thursday (for Sunday). Those lighter red zones are for minimums of 22-24, and that represents a serious threat to emerged flower bud stage which just about everyone in Piedmont is now seeing (even on fields with no covers this winter).

7daytemp.nc.6Fig. 3. This was yesterday’s forecast for Sunday morning, and as you can see the forecast “got worse.”  You can see he virtual disappearance of purple areas in southeast NC in the current minimum temp map above (Fig 2).

I have just now gotten my SkyBit for Clayton as well as a location in Central VA, and all I can say is, “GET READY” for some minimums on Sunday morning that will not only be damaging to open blossoms, but it would appear that with so many areas going into mid-20s and lower, there is good potential for damage to flower buds as well. If you did not apply row covers in anticipation of the cold conditions this weekend, then you will definitely need to really check out your sprinkler system today to make sure it is working properly, as Saturday night/Sunday morning could be a real LuLu (i.e. very tricky conditions related to evaporative cooling and “cold jolt” potential at BOTH start-up and shut-down).

Here is an older bulletin that deals with sprinkler irrigation basics and explains the “cold jolt” problem: StrawberryPlasticulureAdvisoryApril1505

One of the important goals in using irrigation is to make sure you are making CLEAR ICE at all times:

clear iceApplying water at an inadequate rate can result in greater damage to the crop than applying no water at all! If ice-making is occurring too fast (this traps air bubbles in the ice and gives a milky appearance), then you will be cooling the crop to a lower temperature than it would have reached had you done nothing. If you see the formation of “milky ice,” it is essential to increase precipitation rates! (statement from StrawberryPlasticulureAdvisoryApril1505)

For using sprinkler irrigation, you MUST have access to HOURLY wet bulb temperature information (such as shown below), to know when to turn on early Saturday night, and when to shut down on Sunday morning. Go to the section of the advisory below 10-DAY DETAILED HOURLY WEATHER FORECASTS, to see the AWIS forecast of hourly wet bulbs for multiple locations in North Carolina (later in the morning I will add VA, SC, TN, KY and MD).

Hourly wet bulb temps for a location in Farmville, VA: FarmvilleTable 1. For growers who must rely on sprinkling and no row cover, the turn on time on Saturday evening will be when the wet bulb gets to 31 F. Note that this happens at about 1730 (5:30 p.m.) because the wet bulb goes from 33 F at 5 p.m. (1700) to 30 F at 6 p.m. (1800). At 5 p.m. the air temp is 46 F, and at 6 p.m. it will be 42 F. By 7 p.m. (1900) the air temp will be 39, and Dewpoint is NEGATIVE 4 F. This remarkably dry air requires these extra early starting times for sprinkling. At this central VA location, the WB does not get above 30 F until about 10-11 a.m. Sunday.

My SkyBit for Clayton:20150327st1.NCCLYTable 2. Clayton will have canopy low of 22.

7:41 a.m. – Question from grower with similar Skybit to Clayton:

Our sky bit canopy is suppose to be 21 Sunday morning. We are going to cover today. Would it help to turn on water drip during the coldest hours?

Reply:  YES, and with Sunrise of about 7 a.m., I am thinking it would be well to start this procedure at maybe 4:00 a.m. when the air temp will be 23 F (this procedure is best done for a few hours before sunrise, according to my good friend in FL Porter Hare). It could add some valuable heat units in the coldest hours on Sunday morning and make a real difference because a 1.2 oz cover may not make it!

clayt ac

North Carolina Data:

Here is specific information with hourly temperature, dewpoints, winds and wet bulbs for multiple locations across NC (below). Please consult a location near your farm to see the hourly wet bulb info for growers who will be using sprinkling this weekend.

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
AWIS Weather Services, Inc. North Carolina Frost/Freeze Forecast
Produced at  515 a.m. CDT on Fri Mar 27 2015

... Forecast for Tonight ... Northeast NC Coast                      
Currituck/Camden/Pasquotank/Tyrrell Counties      
**** LITTLE IF ANY FROST DUE TO CLOUDS/WIND **** 

Lowest Temperatures:      36 - 42
Elizabeth_City Min          36 
Range Dewpoint Temps:     29 - 47
Range Wetbulb  Temps:     33 - 50
AVG Wind Direction/Speed:   N 11                          
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)

  03/29/15  03/30/15  03/31/15  04/01/15  04/02/15  04/03/15
  --------  --------  --------  --------  --------  --------
   28 - 34   35 - 42   42 - 49   46 - 53   50 - 56   48 - 54
--------

East Central/SE NC Coast                
Carteret/Pamlico Counties                         

**** NEAR FREEZING COLD LOCATIONS  ****
**** LITTLE IF ANY FROST DUE TO CLOUDS/WIND **** 

Lowest Temperatures:      35 - 40
Morehead_City Min           39 
Range Dewpoint Temps:     28 - 52
Range Wetbulb  Temps:     33 - 53
AVG Wind Direction/Speed:  NW 11                          
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)

  03/29/15  03/30/15  03/31/15  04/01/15  04/02/15  04/03/15
  --------  --------  --------  --------  --------  --------
   24 - 30   34 - 38   43 - 46   45 - 48   52 - 56   52 - 54
--------

Southeast NC                            
NWS FORECAST ZONES 87-90,96-101                   

**** NEAR FREEZING COLD LOCATIONS  ****
**** LITTLE IF ANY FROST DUE TO CLOUDS/WIND **** 

Lowest Temperatures:      34 - 41
Elizabethtown Min           40 
Range Dewpoint Temps:     28 - 47
Range Wetbulb  Temps:     35 - 52
AVG Wind Direction/Speed:  NW 10                          
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)

  03/29/15  03/30/15  03/31/15  04/01/15  04/02/15  04/03/15
  --------  --------  --------  --------  --------  --------
   23 - 29   35 - 41   40 - 47   45 - 49   51 - 55   47 - 53
--------

North-Central NC                        
Franklin County Area                              

**** FREEZE COLD LOCATIONS  ****
**** LITTLE IF ANY FROST **** 

Lowest Temperatures:      29 - 40
Louisburg Min               29 
Durations at/below 32:     0 -  5
Range Dewpoint Temps:     24 - 38
Range Wetbulb  Temps:     30 - 41
AVG Wind Direction/Speed:  NW  6                          
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)

  03/29/15  03/30/15  03/31/15  04/01/15  04/02/15  04/03/15
  --------  --------  --------  --------  --------  --------
   20 - 28   33 - 42   37 - 44   43 - 49   49 - 54   45 - 50
--------

North/Central NC                        
Alamance County Area                              

**** FREEZE COLD LOCATIONS  ****
**** LITTLE IF ANY FROST **** 

Lowest Temperatures:      31 - 36
Graham_AG Min               34 
Durations at/below 32:     0 -  3
Range Dewpoint Temps:     24 - 38
Range Wetbulb  Temps:     31 - 41
AVG Wind Direction/Speed:  NW  6                          
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)

  03/29/15  03/30/15  03/31/15  04/01/15  04/02/15  04/03/15
  --------  --------  --------  --------  --------  --------
   22 - 26   37 - 42   39 - 44   44 - 50   49 - 55   46 - 51
--------

South/Central NC                        
Richmond County Area                              

**** FREEZE COLD LOCATIONS  ****
**** LITTLE IF ANY FROST **** 

Lowest Temperatures:      32 - 40
Ellerbe Min                 40 
Durations at/below 32:     0 -  1
Range Dewpoint Temps:     27 - 43
Range Wetbulb  Temps:     31 - 47
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)

  03/29/15  03/30/15  03/31/15  04/01/15  04/02/15  04/03/15
  --------  --------  --------  --------  --------  --------
   25 - 28   37 - 42   41 - 44   45 - 47   50 - 54   47 - 51
--------

Interior/EC-SE NC                       
Wayne County Area                                 

**** NEAR FREEZING COLD LOCATIONS  ****
**** LITTLE IF ANY FROST DUE TO CLOUDS/WIND **** 

Lowest Temperatures:      34 - 38
Goldsboro_AG Min            37 
Range Dewpoint Temps:     28 - 42
Range Wetbulb  Temps:     32 - 43
AVG Wind Direction/Speed:  NW  9                          
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)

  03/29/15  03/30/15  03/31/15  04/01/15  04/02/15  04/03/15
  --------  --------  --------  --------  --------  --------
   25 - 27   33 - 38   41 - 44   44 - 48   51 - 55   49 - 51
--------

For more detailed information visit www.awis.com or call 888-798-9955. Copyright 2015 AWIS Weather Services, Inc. All rights reserved.

Good luck!

Barclay

Updated on Mar 27, 2015
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