Frost/Freeze Update - late afternoon Friday (3/17)

Dear Grower,

Date: Fri, 17 Mar 2000 13:50:08 -0500
From: The Agmaster (agmaster@drought.meso.com)
To: barclay_poling@ncsu.edu
Subject: 'SkyBit Frost Advisory 000317'

E-WEATHER FROST/FREEZE ALERT FOR THE SOUTHEAST
Issued: 03/17/00
GENERAL SUMMARY

The combination of cold, Canadian air and mainly clear skies will
promote isolated frosts early Saturday morning. A storm system should
spread cloudiness into this region Saturday night. If skies are cloudy
enough, frost would be unlikely early Sunday morning.

STATE-BY-STATE SUMMARY

NORTH CAROLINA, SOUTH CAROLINA, VIRGINIA
Mostly clear and cold early Saturday morning with low temperatures of
27-32F. Winds northeast at 4-8 mph after midnight. Dew points
lowering into the 20s.

Copyright(C) 2000, SkyBit, Inc.

Please Note:

This frost/freeze differs from last week in that we have some winds to deal with tonight and a lower dewpoint. In speaking to SkyBit's Ag Meteorologist late this afternoon (March 17) there is going to be a good liklihood of winds in the 4-8 mph range (see precipitation rates below). If you reach a low temperature tomorrow morning of say 27 F, then you will need an irrigation rate of up to 0.14 inch/hour (5-8mph). Also, lower dewpoints require that you start-up the system at a higher temperature. Last week, a start-up of 32 - 33 F was fine, but we need to think in terms of starting the system tonight at about 34 -35 F. There could be a lot of water pumped tonight, and it will be important early next week to make a fungicide application for botrytis control. Good luck!

Table 1. Required irrigation rates, in/hr, for a critical temperature of 28 F
and relative humidity of about 70%.

Air Wind Speed, mph
Temp.
F 0-1 2-4 5-8 9-14*
27 0.10 0.11 0.14 0.16
26 0.10 0.13 0.16 0.17
25 0.10 0.14 0.18 0.21
22 0.10 0.18 0.24 0.29
20 0.11 0.21 0.28 0.34
18 0.12 0.23 0.31 0.38
16 0.13 0.26 0.35 0.43