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Threat of dangerous surf and rip currents continues for East Coast due to Jose

Tropical Storm Jose will continue to weaken as it moves northeastward then returns southwestward while remaining off the Northeast coast. Jose will produce rain with embedded thunderstorms over parts of coastal Southern New England through Friday. Swells generated by Jose will bring the risk of dangerous surf and rip current conditions for much of the U.S. east coast during the next several days. Read More >

PEAC Seasonal Sea Level Outlook


September - October - November (SON) 2017

 

The following sections describe: (i) the Canonical Correlation Analysis (CCA)-based forecasts for the seasonal MEAN and MAXIMUM sea level anomaly in the SON season of 2017, and (ii) the monthly sea level anomaly observed in the previous season, June - July - August (JJA) of 2017. See Figure 2 at right for location of USAPI tide guage stations.

Note that 'anomalies' are defined as 'deviations or departures from the normal' using 1983-2001 mean sea level values computed at each station. Also, note that the forecasting technique used here does not account for sea level anomalies created by other atmospheric or geological conditions such as tropical cyclones, storm surges or tsunamis.

(i) Seasonal Sea Level Outlook SON 2017

Based on the independent SST values observed in the JJA 2017 season, the resulting CCA model has been used to forecast the sea-level for the SON 2017 season (see Table 1).

tide station location
 
Table 1 : Forecasts of MEAN and MAX sea level anomaly in inches for SON 2017
 
Tide Gauge Station
Forecast Anomaly for SON 2017 (in inches)
 

MEAN
Deviation(1)

Standard Deviation 
SON season
MAX
Deviation (2)
Standard Deviation of SON season
Marianas, Guam
+4
3.5
+20
3.3
Malakal, Palau
+3
4.4
+40
4.2
Yap, FSM 1
+4
4.7
+33
4.9
Chuuk, FSM**
+4
*
+32
*
Pohnpei, FSM
+4
34.3
+34
4.5
Kapingamarangi, FSM
*
*
*
*
Majuro, RMI
+4
3.3
+44
3.7
Kwajalein, RMI
+4
3.5
+42
3.8
Pago Pago, American Samoa
+5
(0)
3.1
+31
(+26)
3.2
Honolulu, Hawaii
+3
1.8
+21
2.5
Hilo, Hawaii
+2
1.8
+23
2.4

+/- indicate positive anomaly (rise) and negative anomaly (fall) respectively. Note that any changes between (0~ ±1) inch is considered to be negligible. Also note that changes within the range of (+/-) 2 inches are unlikely to cause any adverse climatic impact. *** Guesstimated values, ** Data currently unavailable; Figures in parenthesis are year-to-year seasonal anomaly.

1: Difference between the mean sea level for the given month and the 1983 through 2001 mean sea level value at each station (seasonal cycle removed); 2: Same as 1 except for maxima; SD stands for standard deviations.

* In Pago Pago, There was a level shift (approximately 5 inches) in American Samoa at the time of September 2009 earthquake. So, -5 inches has been adjusted (shown in parenthesis) to the current tide-gauge values of Pago Pago. 

 

Forecasts for SON: PEAC-CCA statistical model is predicting above normal sea levels with reasonably high skill. Complementary to PEAC forecasts, some dynamical models are also predicted high sea levels which are based on upper ocean interactions with the atmosphere and Earth’s rotation. High seasonal sea levels, combined with gradually rising oceans because of greenhouse warming, and large astronomical tides (i.e., King Tides) potentially could impact islands with minor coastal flooding or salt water intrusions and increase vulnerability to flooding from storms or large waves

 

(ii) Observed Monthly Sea Level Deviation in  JJA 2017

The monthly time series (JJA 2017) for sea-level anomaly has been taken from the UH Sea Level Center. 

Current Conditions: It is ENSO-neutral, but atmospheric and oceanic signals are leaning towards La Niña. La Niña means higher-than-average sea level in the vicinity of USAPIs. As a result, other than Palau, currently, all stations are above normal. Among others, Guam is 9 inches above normal. All FSM and RMIs are also above normal. This could potentially impact islands with minor coastal flooding or salt water intrusions and increase vulnerability to flooding from storms or large waves.

A combination of the highest astronomical tides of the year ("King Tides"), global sea level rise, delayed sea level effects from the 2014-2016 El Niño, Pacific-wide climate, and localized eddies have caused record-breaking sea level heights in HawaiĘ»i in JJA.

 

 

Table 2 : Observed MEAN anomaly and MAX sea level in inches for JJA 2017

 
Tide Gauge Station
Observed MEAN Sea Level 
Anomaly
Observed MAX Sea Level
 
June
2017
July
2017
August
2017
Standard Deviation of the JJA mean
June
2017
July
2017
August
2017
Standard Deviation of the JJA max
Marianas, Guam
+5
+6
+9
3.5
+22
+22
+22
4.6
Malakal, Palau
+1
+1
+1
4.4
+38
+37
+38
4.4
Yap, FSM
+7
+8
+6
3.9
+37
+33
+33
3.9
Chuuk, FSM
+4
+4
+5
*
*
*
*
*
Pohnpei, FSM
+5
+5
*
3.1
35
35
*
3.3
Kapingamarangi +4 +4 +3 * +31 +32 +28 *
Majuro, RMI
+3
+3
*
2.4
+42
+42
*
2.6
Kwajalein, RMI
+3
+3
+5
2.8
+40
+39
+38
3.0
Pago Pago, American Samoa
+10
(+5)
+8
(+3)
+9
3.6
+33
+33
+33
3.7
Honolulu, Hawaii
+5
+4
+8
1.7
+29
+24
+28
2.3
Hilo, Hawaii
+4
+6
+6
2.0
+28
+33
+28
2.6
Denotes where data is unavailable