AGROCLIMATIC INFORMATION FOR AGRICULTURAL PLANNING AND OPERATION IN ILOCOS NORTE PARTICULARLY BATAC AND SURROUNDING AREAS FOR THE MONTH OF JULY

I. AGROCLIMATIC SUMMARY::

Generally cloudy skies with scattered to occasional rains is the normal weather in the area. Total rainfall amount averages 405.4 mm with 16 rainy days. Southwest monsoon rains usually prevail. Total evaporation of 142.0 mm are the normal values for the month.

Soil moisture is generally wet and it is conducive for farming and planting of lowland rice. Humid environment is felt during the month so drying condition is poor. Leaf wetness duration is from 6 to 12 hours. Daylight duration is 13 hours and 03 minutes with 41% total bright sunshine. This situation gives an amount of 19 MJ/m2 of solar radiation during most days of the month. Southerly to southeasterly winds prevail.

The normal maximum and minimum air temperature is 32.4 °C and 23.9 °C.

II. AGROCLIMATIC DATA (AVERAGE)::

Decade Rainfall Rainy P(W)* P(TC)** Tot AIR TEMPERATURE RH Solar Wind
(10 Day) (mm) days % % evap. Max. Min. (%) Rad. Speed
          (mm) (°C) (°C)   MJ/m2 (kpd)
July                    
1-10 146.6 5 50 29 48.1 32.5 24.0 83 19.0 46.8
11-20 99.6 5 50 38 47.2 32.7 23.8 83 19.2 42.9
21-31 159.2 6 79 38 46.7 32.1 24.0 84 18.1 52.3

Ten-day rainfall depth at different probability levels for July in Batac, Ilocos Norte

Decade Mean Rainfall Probable rainfall depth
    25% 50%
1-10 113.6 115.0 18.5
11-20 85.2 87.6 10.0
21-31 176.2 203.4 43.2

* Probability of wet decade (>50 mm per decade)

** Probability of having a Tropical Cyclone

Initial probabilities that a given decade is dry (D) or wet (W) and transitional probabilities that one, two or three days within a decade is dry or wet.

July Initial
(%)
Transitional %
D W DD WD DW WW DDD WDD DWD DDW WWD WDW DWW WWW
1-10 50 50 50 56 44 45 14 16 8 11 7 12 18 15
11-20 45 55 56 44 30 70 13 8 3 13 5 8 17 33
21-31 20 80 50 50 13 87 2 2 3 8 23 9 7 47
DD -- probability of a dry day given that the previous day was dry
DW -- probability of a dry day given that the previous day was wet
WD -- probability of a wet day given that the previous day was dry
WW -- probability of a wet day given that the previous day was wet
DDD -- probability that three consecutive days are dry
WWW -- probability that three consecutive days are wet
WWD -- probability that two consecutive days are wet and the third day is dry
WDW -- probability that within three days the second day is dry

III. TROPICAL CYCLONE

Northern Luzon which includes Ilocos Norte is within the normal tropical cyclone track. Historical record shows the following tropical disturbances that crossed or passed closed over the area (1981-2006).

TC Name Year and Date Occurrence
TS Juling July 19-21, 1981
T Iliang July 27-29, 1982
TS Biring July 2, 1984
T Gading July 8-10, 1986
T Huaning July 17-19, 1988
T Goring July 14-16, 1989
TS Deling July 5-10, 1990
TD Emang July 27-29, 1990
T Gening July 16-19, 1991
TS Herming July 20-23, 1991
TD Ditang July 17-21 1992
TS Narsing July 28-29, 1993
T Emang July 4-6, 1994
T Iliang July 7-10, 1994
TS Loleng July 10-11, 1994
TD Miding July 14-16, 1994
TD Norming July 18-20, 1994
TD Karing July 27-31, 1995
T Gloring July 21-27, 1996
T Huaning July 28-31, 1996
TD-T Edeng July 2-9, 2000
TD Gloring July 13-14, 2000
TD Huaning July 21-24, 2000
T Feria July 3-5, 2001
TS Gorio July 10-11, 2001
TS Huaning July 23-24, 2001
T Isang July 27-29, 2001
T Gloria July 7-9, 2002
TS Hambalos July 8-9, 2002
T Inday July 12-14, 2002
T Harurot July 19-23, 2003
TS Julian July 14, 2004
T Feria July 17-19, 2005
T Ester July 6-9, 2006
T Florita July 10-14, 2006
T Glenda July 23-26, 2006
TD Henry July 29-Aug. 1, 2006

RAINFALL DEPTH AT DIFFERENT PROBABILITIES OF OCCURRENCE FOR JULY 1-31

DATE RAINFALL DEPTH (mm)
25% 50%
1 16.9 4.8
2 7.2 0.8
3 16.1 3.8
4 6.8 1.5
5 4.6 0
6 3.0 0
7 4.2 0
8 13.7 2.4
9 25.4 3.0
10 17.2 2.2
11 16.0 0.6
12 3.0 0.4
13 3.8 0
14 3.2 0.4
15 5.8 0.4
16 4.6 0
17 8.8 1.4
18 26.2 3.6
19 10.4 2.8
20 5.8 0.4
21 10.2 3.0
22 3.2 0
23 13.2 0
24 29.2 8.4
25 25.0 1.5
26 15.2 3.6
27 31.2 9.2
28 30.6 5.8
29 15.8 6.9
30 13.8 2.6
31 16.0 2.2

DAILY RAINFALL PROBABILITY (GRAPH)