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Hurricane ANDRES Forecast Discussion Number 14

2015-05-31 16:32:45| National Hurricane Center (East Pacific)

Issued at 800 AM PDT SUN MAY 31 2015 000 WTPZ41 KNHC 311432 TCDEP1 HURRICANE ANDRES DISCUSSION NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL EP012015 800 AM PDT SUN MAY 31 2015 Andres appears to be maintaining its strength for now. The cloud pattern of the hurricane consists of a central dense overcast with an eye occasionally evident in infrared satellite images. There is some indication of drier air wrapping around the circulation as seen in total precipitate water imagery. The Dvorak classifications from TAFB, SAB, and UW-CIMSS were generally the same as the previous cycle, so the initial wind speed estimate remains 90 kt. Steady weakening is anticipated to begin by tonight when the hurricane moves over progressively cooler water and into a much more stable air mass. Andres is expected to become a remnant low by the end of the forecast period, when it is forecast to be over sea surface temperatures cooler than 24 C. The official intensity forecast is unchanged from the previous one and is in line with much of the guidance. Andres has made the expected turn toward the west-northwest, and the latest initial motion estimate is 290/7. This general motion is expected to continue for the next few days while the system remains on the southwestern side of a mid-level ridge. After that time, there remains significant spread in the model guidance. The GFS, GEFS ensemble mean, UKMET, and HWRF models show Andres stalling and then turning northeastward toward a mid- to upper-level trough. Conversely, the ECMWF model shows Andres moving slowly westward during the 72-120 hour time frame in the low-level flow. The official track forecast is a little north of and slower than the previous one at 72 hours and beyond. This forecast continues to lean toward the ECMWF model, especially in the longer range, which appears to have the most realistic solution of a decaying tropical cyclone moving over cool water. FORECAST POSITIONS AND MAX WINDS INIT 31/1500Z 15.5N 118.1W 90 KT 105 MPH 12H 01/0000Z 15.8N 119.0W 85 KT 100 MPH 24H 01/1200Z 16.4N 120.3W 75 KT 85 MPH 36H 02/0000Z 17.0N 121.8W 65 KT 75 MPH 48H 02/1200Z 17.8N 123.5W 55 KT 65 MPH 72H 03/1200Z 19.3N 126.0W 40 KT 45 MPH 96H 04/1200Z 19.8N 126.8W 30 KT 35 MPH 120H 05/1200Z 19.9N 127.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Cangialosi

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Hurricane ANDRES Forecast Discussion Number 12

2015-05-31 04:52:45| National Hurricane Center (East Pacific)

Issued at 800 PM PDT SAT MAY 30 2015 000 WTPZ41 KNHC 310252 TCDEP1 HURRICANE ANDRES DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL EP012015 800 PM PDT SAT MAY 30 2015 Andres has strengthened further today despite moderate northwesterly shear. The cyclone had been maintaining a symmetric central dense overcast (CDO), and the eye had slowly warmed until about 0000 UTC. Over the past few hours though, the CDO has become more irregularly shaped and the eye more indistinct. Dvorak T-numbers were 5.5/102 kt at 0000 UTC from both agencies, and UW-CIMSS ADT values leveled off at 5.7/107 kt. These data suggest that Andres may have been a major hurricane at that time, but satellite data suggest that the cyclone has since begun to weaken. The initial intensity is set at 95 kt, slightly lower than 0000 UTC intensity estimates. Andres is still moving generally northwestward in response to a weakness in the subtropical ridge around 120w. Most of the track guidance shows a high pressure ridge north of the cyclone strengthening on Sunday which should cause the cyclone to turn west-northwestward. Beyond 48 hours, the track models significantly diverge, with the GFS-based guidance depicting a stronger cyclone being steered northwestward over cool waters, followed by an eastward turn. The ECMWF shows a weaker version of Andres eventually turning westward, with its solution on the southern side of the guidance envelope. The official NHC forecast is close to the multi- model consensus (TVCE) through 36 hours. After that, the overly strong GFS run is disregarded, resulting in a track forecast relatively far left of TVCE. The shear over Andres is forecast to decrease dramatically within 24 hours, but the cyclone will be moving over gradually cooler waters and ingesting drier and more stable air during the next couple of days. This competition between dynamic and thermodynamic factors should result in a slow weakening through 48 hours. After that time, even more unfavorable thermodynamic conditions could result in a quicker rate of weakening, and Andres is expected to become a remnant low by day 5. The NHC intensity forecast is close to LGEM and somewhat lower than the multi-model consensus ICON. FORECAST POSITIONS AND MAX WINDS INIT 31/0300Z 15.1N 116.8W 95 KT 110 MPH 12H 31/1200Z 15.6N 117.8W 95 KT 110 MPH 24H 01/0000Z 16.1N 119.1W 85 KT 100 MPH 36H 01/1200Z 16.5N 120.4W 75 KT 85 MPH 48H 02/0000Z 17.0N 122.0W 65 KT 75 MPH 72H 03/0000Z 18.4N 125.1W 50 KT 60 MPH 96H 04/0000Z 19.3N 128.2W 35 KT 40 MPH 120H 05/0000Z 19.3N 130.1W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Kimberlain

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Hurricane ANDRES Forecast Discussion Number 11

2015-05-30 22:37:12| National Hurricane Center (East Pacific)

Issued at 200 PM PDT SAT MAY 30 2015 000 WTPZ41 KNHC 302037 TCDEP1 HURRICANE ANDRES DISCUSSION NUMBER 11 NWS NATIONAL HURRICANE CENTER MIAMI FL EP012015 200 PM PDT SAT MAY 30 2015 Andres' cloud pattern has not changed much during the last several hours. The eye of the hurricane remains evident in visible and infrared satellite images, but it has been occasionally obscured by high-level clouds. Recent microwave data show that the western side of the eyewall has eroded slightly, which is likely the result of northwesterly shear and drier air that is wrapping into that side of the circulation. The Dvorak classifications from TAFB, SAB, and the UW-CIMSS ADT are all 5.0/90 kt, and accordingly, the initial wind speed is held at that value. Andres continues on a northwestward track at about 6 kt toward a weakness in the subtropical ridge. The models are in agreement that the hurricane should turn west-northwestward tonight or early Sunday when the ridge builds to the north of the cyclone. The 12Z GFS solution has changed considerably from the previous cycle, and now shows Andres stalling and then moving eastward in the 96-120 hour time frame in response to a mid- to upper-level trough. That model is considered an outlier as it is likely keeping Andres too deep over cool waters. The official track forecast is a little to the north and slightly slower than the previous one after 72 hours. The hurricane is forecast to maintain its strength for about a day while it remains over warm water and in an environment of decreasing shear. Steady weakening is anticipated beyond that time, however, when Andres moves over progressively cooler water and into a much more stable air mass. The official intensity forecast is basically an update of the previous one and is in good agreement with the intensity model consensus. The 34-kt and 50-kt wind radii were expanded on the east side of the circulation based on a 1650 UTC ASCAT-B pass. The 12-ft sea radii were also expanded based on a recent altimeter pass that showed sea heights as high as 28 ft. FORECAST POSITIONS AND MAX WINDS INIT 30/2100Z 14.8N 116.3W 90 KT 105 MPH 12H 31/0600Z 15.4N 117.4W 90 KT 105 MPH 24H 31/1800Z 15.9N 118.6W 85 KT 100 MPH 36H 01/0600Z 16.3N 119.8W 75 KT 85 MPH 48H 01/1800Z 16.9N 121.2W 65 KT 75 MPH 72H 02/1800Z 18.5N 124.2W 55 KT 65 MPH 96H 03/1800Z 19.5N 127.3W 40 KT 45 MPH 120H 04/1800Z 19.5N 129.0W 30 KT 35 MPH $$ Forecaster Cangialosi

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Hurricane ANDRES Forecast Discussion Number 10

2015-05-30 16:35:14| National Hurricane Center (East Pacific)

Issued at 800 AM PDT SAT MAY 30 2015 000 WTPZ41 KNHC 301435 TCDEP1 HURRICANE ANDRES DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL EP012015 800 AM PDT SAT MAY 30 2015 Andres has strengthened a little more this morning. The cloud pattern has become better organized with the eye of the hurricane intermittently appearing in satellite images. Recent microwave data show a well-defined eyewall, but most of the banding features are concentrated on the east side of the circulation, likely due to northwesterly shear. The initial intensity is raised to 90 kt, in agreement with the Dvorak classifications from TAFB and SAB, making Andres a category 2 hurricane on the Saffir-Simpson Hurricane Wind Scale. The hurricane still has about another day over warm water and the SHIPS model lowers the current shear during that time. Therefore, some additional short-term strengthening is possible even though none of the models suggest intensification. After that time, however, Andres is expected to move over progressively cooler water and into a more stable airmass. These unfavorable conditions should promote a steady weakening trend. The official forecast is a little higher than the previous one during the next 36 hours to account for the higher initial intensity. Andres is moving northwestward at about 6 kt toward a weakness in the subtropical ridge. A turn to the west-northwest is expected to occur tonight or on Sunday when the ridge builds to the north of the hurricane, and that general motion should continue for the remainder of the forecast period. Little change was made to the previous forecast track, and it lies close to the middle of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 30/1500Z 14.5N 115.9W 90 KT 105 MPH 12H 31/0000Z 15.1N 116.8W 95 KT 110 MPH 24H 31/1200Z 15.8N 118.0W 90 KT 105 MPH 36H 01/0000Z 16.3N 119.2W 80 KT 90 MPH 48H 01/1200Z 16.8N 120.6W 70 KT 80 MPH 72H 02/1200Z 18.2N 123.7W 60 KT 70 MPH 96H 03/1200Z 19.1N 127.1W 45 KT 50 MPH 120H 04/1200Z 19.2N 129.6W 35 KT 40 MPH $$ Forecaster Cangialosi

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Hurricane ANDRES Forecast Discussion Number 9

2015-05-30 10:37:42| National Hurricane Center (East Pacific)

Issued at 200 AM PDT SAT MAY 30 2015 000 WTPZ41 KNHC 300837 TCDEP1 HURRICANE ANDRES DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL EP012015 200 AM PDT SAT MAY 30 2015 Andres is producing a relatively compact area of strong convection, but the high-level cirrus canopy continues to obscure an eye in infrared satellite imagery. A 0501 UTC AMSU pass showed that the bulk of the deep convection is located within the eastern and southern eyewall--probably the result of 15-20 kt of north- northwesterly shear. Nonetheless, Dvorak estimates have notched upward just a bit (T5.0/90 kt from TAFB, T4.5/77 kt from SAB, and T4.5/77 kt from the UW-CIMSS ADT), and the initial intensity is therefore set at 80 kt. The hurricane is currently located due south of a weakness in the subtropical ridge, resulting in a northwestward motion of 325/6 kt. Mid-level ridging is expected to strengthen to the north and northwest of Andres during the next couple of days, which should induce a west-northwestward turn by tonight. The track guidance is in good agreement during the first 48 hours but then diverges thereafter. The GFS appears to keep Andres as a hurricane for too long after it reaches colder water, and its solution is therefore considered to be a northern outlier. Otherwise, the remainder of the guidance is in relatively good agreement, and the official track forecast is nearly on top of the previous one. Global model fields and SHIPS guidance suggest that the shear affecting Andres will continue for another 18-24 hours. However, the shear doesn't appear quite strong enough to significantly disrupt the circulation, and the thermodynamic environment remains conducive for some further short-term strengthening. After 24 hours, the oceanic heat content falls to zero, so Andres will begin to upwell colder water and start a steady weakening trend that will continue through the end of the forecast period. The intensity guidance is in general agreement of this scenario, and the new NHC intensity forecast is just an update of the 0300Z forecast, close to the multi-model consensus (ICON). FORECAST POSITIONS AND MAX WINDS INIT 30/0900Z 14.0N 115.6W 80 KT 90 MPH 12H 30/1800Z 14.7N 116.4W 85 KT 100 MPH 24H 31/0600Z 15.4N 117.6W 80 KT 90 MPH 36H 31/1800Z 16.0N 118.8W 75 KT 85 MPH 48H 01/0600Z 16.5N 120.0W 70 KT 80 MPH 72H 02/0600Z 17.8N 122.9W 60 KT 70 MPH 96H 03/0600Z 19.0N 126.5W 50 KT 60 MPH 120H 04/0600Z 19.0N 129.5W 35 KT 40 MPH $$ Forecaster Berg

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