Minimal Cold Threat in NC for Tuesday Morning (Issued 2:30pm on Mon., 3/17/14)

— Written By Barclay Poling

Minimal temperatures in NC on Tuesday morning for multiple cities/towns: NC AWIS MIN TEMPS ON TUE MORNING

Dear Growers, Agents, Agronomists & Others,

I have had a few calls this morning about need to apply row covers today for cold protection. The AWIS NC Frost/freeze forecast (below) is saying  there is little if any frost likely due to clouds/winds. However, in one of the locations covered by this AWIS forecast (Ellerbe – a Sandhills location), it is indicated that FREEZING (below 32 F) temperatures are possible tomorrow morning. But it is important to bear in mind that open blossoms can tolerate temperatures a few degrees below 32 F without injury.

It is also important to note that for all the eastern NC locations covered in this advisory as well as central piedmont and sandhills that it says: **** LITTLE IF ANY FROST DUE TO CLOUDS/WIND ****  Thus, in the absence of a frost threat, we are stricly concerned with the minimum temperatures tomorrow morning, and those minimum temperatures are shown in Figure 1.

7daytemp.nc.2

Fig. 1.The purple areas will possibly reach 28 F tomorrow morning, and the pink areas will possibly reach 30 F (including Raleigh). The Sandhills region will be in the 32-34 range, and coastal plain will have minimums of perhaps 34 F. In colder areas of the state the crop is not as advanced, and emerged tight buds can tolerate temperatues into the low and mid 20s.

It is diffcult to pinpoint critical temperatures

Fig. 2. Growers in the Coastal areas, interior coastal plain, sandhills and eastern piedmont areas are concerned about temperatures that could drop below 28 F, but that does not appear to be likely in these areas tomorrow morning.

So, in studying the AWIS forecast information below for 3/18, I don’t see many “red flags” for potential damage to open blossoms, and the popcorn and emerged tight bud stages look quite safe for the areas covered in the AWIS NC Frost/Freeze Forecast (at bottom of advisory). If you have a row crop “ON” already, that is not a problem. Hopefully, the covers can come off Thursday when some better weather conditions will return to the state! On sunny days you want the crop “open” to the sky if the crop is in bloom. Honeybees and wind movement are VIP for strawberry polliination. And, you don’t want those open blooms trapped beneath a damp row cover on a day that is going to be ideal for pollination.

Summary:  The chance of a radiation frost tomorrow morning is very slight due to clouds/rain/winds. If we assume a critical temperature of 28 F for an open blossom, the only area of the state “at risk” is the Upper Mountains. But, in the Upper Mountains, the crop is significantly behind in development and temperatures of 26-28 F will not injure   tight buds. As far as my own Clayton Skybit, it is only showing a low of only 36 tomorrow morning in the canopy. Canopy and air temp (weather shelter) are basically the same under these environmental conditions (note the black dots indicating clouds all the way through until tomorrow morning – further confirmation of what AWIS is also saying in their Frost/Freeze forecast).

20140317st1.NCCLY

B. Poling

AWIS Weather Services, Inc. North Carolina Frost/Freeze Forecast
Produced at  508 a.m. CDT on Mon Mar 17 2014

... Forecast for Tonight ... Northeast NC Coast                      
Currituck/Camden/Pasquotank/Tyrrell Counties      

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

Lowest Temperatures:      35 - 41
Elizabeth_City Min          36 
Range Dewpoint Temps:     30 - 40
Range Wetbulb  Temps:     33 - 43
AVG Wind Direction/Speed:  NE 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)

  03/19/14  03/20/14  03/21/14  03/22/14  03/23/14  03/24/14
  --------  --------  --------  --------  --------  --------
   41 - 47   45 - 51   39 - 46   45 - 51   45 - 51   33 - 41
--------

East Central/SE NC Coast                
Carteret/Pamlico Counties                         
**** LITTLE IF ANY FROST DUE TO CLOUDS/WIND **** 

Lowest Temperatures:      37 - 42
Morehead_City Min           39 
Range Dewpoint Temps:     33 - 41
Range Wetbulb  Temps:     35 - 45
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)

  03/19/14  03/20/14  03/21/14  03/22/14  03/23/14  03/24/14
  --------  --------  --------  --------  --------  --------
   40 - 46   51 - 52   40 - 44   47 - 50   48 - 51   37 - 41
--------

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

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

Lowest Temperatures:      33 - 38
Elizabethtown Min           36 
Range Dewpoint Temps:     32 - 41
Range Wetbulb  Temps:     33 - 41
AVG Wind Direction/Speed:  NE 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)

  03/19/14  03/20/14  03/21/14  03/22/14  03/23/14  03/24/14
  --------  --------  --------  --------  --------  --------
   38 - 42   47 - 54   38 - 43   47 - 52   47 - 52   37 - 41
--------

North-Central NC                        
Franklin County Area                              

**** FREEZING TEMPERATURES ****
**** LITTLE IF ANY FROST DUE TO CLOUDS **** 

Lowest Temperatures:      26 - 36
Louisburg Min               26 
Durations at/below 32:     0 - 15
Durations at/below 28:     0 -  7
Range Dewpoint Temps:     26 - 31
Range Wetbulb  Temps:     28 - 32
AVG Wind Direction/Speed:  NE  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)

  03/19/14  03/20/14  03/21/14  03/22/14  03/23/14  03/24/14
  --------  --------  --------  --------  --------  --------
   33 - 41   38 - 48   35 - 42   43 - 50   40 - 47   32 - 39
--------

North/Central NC                        
Alamance County Area                              

**** FREEZING TEMPERATURES ****
**** LITTLE IF ANY FROST DUE TO CLOUDS/WIND **** 

Lowest Temperatures:      28 - 33
Graham_AG Min               30 
Durations at/below 32:     0 - 15
Durations at/below 28:     0 -  2
Range Dewpoint Temps:     25 - 31
Range Wetbulb  Temps:     28 - 32
AVG Wind Direction/Speed:  NE  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)

  03/19/14  03/20/14  03/21/14  03/22/14  03/23/14  03/24/14
  --------  --------  --------  --------  --------  --------
   35 - 40   39 - 44   36 - 41   45 - 50   42 - 47   34 - 39
--------

South/Central NC                        
Richmond County Area                              

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

Lowest Temperatures:      31 - 35
Ellerbe Min                 35 
Durations at/below 32:     0 -  4
Range Dewpoint Temps:     28 - 36
Range Wetbulb  Temps:     31 - 36
AVG Wind Direction/Speed:  NE 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)

  03/19/14  03/20/14  03/21/14  03/22/14  03/23/14  03/24/14
  --------  --------  --------  --------  --------  --------
   36 - 40   41 - 51   38 - 41   45 - 50   43 - 50   37 - 40
--------

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