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Tropical Storm Cristina Forecast Discussion Number 13

2020-07-09 22:36:57| National Hurricane Center (East Pacific)

Issued at 300 PM MDT Thu Jul 09 2020 437 WTPZ45 KNHC 092036 TCDEP5 Tropical Storm Cristina Discussion Number 13 NWS National Hurricane Center Miami FL EP052020 300 PM MDT Thu Jul 09 2020 Satellite images and microwave data indicate that the structure of Cristina has improved since this morning. Banding features have become more prevalent, while deep convection has persisted over the center throughout the day. In addition, the average of the satellite intensity estimates from TAFB and SAB has increased since this morning's advisory. Therefore, the initial intensity has been raised to 60 kt. The storm will remain in a favorable environment for intensification through Friday morning, and it is expected to become a hurricane by that time. By late Friday, the cyclone will cross the 26 C isotherm and move into a progressively more stable and dry atmospheric environment. This should result in steady weakening. There is some spread in the guidance as to how quickly Cristina will lose its convection later on in the forecast period. The GFS suggests this will not occur until 120 h, while the Canadian and ECMWF indicate this will happen in 96 h and 72 h, respectively. Based on a blend of these, Cristina is now expected to become a remnant low by 96 h. The NHC intensity forecast is very similar to the previous one and is close to the consensus aids. Cristina's initial motion is west-northwest at 10 kt. The mid-level ridge centered over the southwestern U.S. is expected to strengthen a little over the next day or so, which should keep Cristina on the same path but with a slight increase in forward speed. Over the weekend, as the cyclone weakens, a gradual turn to the west is expected. The guidance shifted slightly northward beyond day 3, so the NHC track forecasted was nudged a little north for that time frame. Otherwise, the latest NHC track forecast is little changed compared to the previous one. FORECAST POSITIONS AND MAX WINDS INIT 09/2100Z 17.9N 111.1W 60 KT 70 MPH 12H 10/0600Z 18.7N 112.6W 65 KT 75 MPH 24H 10/1800Z 19.7N 115.0W 65 KT 75 MPH 36H 11/0600Z 20.5N 117.8W 60 KT 70 MPH 48H 11/1800Z 21.0N 120.7W 55 KT 65 MPH 60H 12/0600Z 21.4N 123.5W 45 KT 50 MPH 72H 12/1800Z 21.5N 126.3W 40 KT 45 MPH 96H 13/1800Z 21.9N 131.9W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 14/1800Z 22.3N 137.3W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Latto

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Tropical Storm Cristina Forecast Discussion Number 12

2020-07-09 16:42:56| National Hurricane Center (East Pacific)

Issued at 900 AM MDT Thu Jul 09 2020 000 WTPZ45 KNHC 091442 TCDEP5 Tropical Storm Cristina Discussion Number 12 NWS National Hurricane Center Miami FL EP052020 900 AM MDT Thu Jul 09 2020 Cristina's convective structure has evolved into a large curved band over the past several hours. The improving appearance has not yet materialized in an increase in intensity, but may be indicative that some strengthening may soon occur. The initial wind speed estimate of 55 kt, is based on the most recent TAFB Dvorak satellite intensity estimate. The storm will remain in a favorable environment for intensification for another 24 h or so. And, with the convective structure beginning to show some improvement, it is reasonable to assume that some strengthening is likely through tonight. After 24 h, the cyclone will cross the 26 C isotherm and move into a progressively more stable and dry atmospheric environment. This should result in steady weakening. By 120 h, Cristina is expected to have lost all of its deep convection and become a remnant low. The official forecast is essentially an update of the previous one, indicating that Cristina should become a hurricane by tomorrow morning and then begin to weaken shortly thereafter. Cristina's initial motion is west-northwest at 9 kt. A mid-level ridge centered over the southwestern U.S. is expected to strengthen a little over the next day or so, which should keep Cristina on the same path but with a slight increase in forward speed. Over the weekend, as the cyclone weakens, a gradual turn to the west is expected. The latest NHC track forecast is very similar to the previous one, and is in the middle of tightly clustered guidance. FORECAST POSITIONS AND MAX WINDS INIT 09/1500Z 17.4N 110.2W 55 KT 65 MPH 12H 10/0000Z 18.2N 111.6W 60 KT 70 MPH 24H 10/1200Z 19.2N 113.8W 65 KT 75 MPH 36H 11/0000Z 20.1N 116.6W 60 KT 70 MPH 48H 11/1200Z 20.7N 119.5W 55 KT 65 MPH 60H 12/0000Z 21.1N 122.5W 50 KT 60 MPH 72H 12/1200Z 21.2N 125.5W 45 KT 50 MPH 96H 13/1200Z 21.4N 131.3W 35 KT 40 MPH 120H 14/1200Z 21.5N 137.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Latto

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Tropical Storm Cristina Forecast Discussion Number 11

2020-07-09 10:31:21| National Hurricane Center (East Pacific)

Issued at 300 AM MDT Thu Jul 09 2020 000 WTPZ45 KNHC 090831 TCDEP5 Tropical Storm Cristina Discussion Number 11 NWS National Hurricane Center Miami FL EP052020 300 AM MDT Thu Jul 09 2020 Although deep convection has been increasing tonight in association with Cristina, the overall cloud pattern and structure of the storm has changed little and it continues to lack banding features. The satellite intensity estimates range from 45 to 60 kt, and a recent ASCAT pass showed maximum winds of around 40 kt. Based on these data, the initial intensity is held at a possibly generous 55 kt. Cristina has not strengthened as much as anticipated. However, the storm still has about another 36 hours in favorable environmental conditions of wind shear of 10 kt or less, mid-level humidities between 75 and 80 percent, and SSTs of 26 C or warmer. During that period it still seems likely that Cristina will strengthen and it could become a hurricane. After 36 hours, Cristina is expected to move over much cooler waters and into a notably drier and more stable air mass. These conditions should promote a steady weakening trend, and Cristina will likely become a remnant low in 4 or 5 days. The NHC intensity forecast is a little lower than the previous one and in good agreement with the IVCN consensus model. The storm is moving west-northwestward at about 10 kt. A mid-level ridge located over the southwestern U.S. is expected to strengthen in place, and that should cause Cristina to move a little faster to the west-northwest during the next few days. After that time, the weaker and likely vertically shallow storm should turn toward the west in the low-level trade wind flow. The model tracks remain tightly packed, and the new NHC track forecast is largely an update of the previous one. FORECAST POSITIONS AND MAX WINDS INIT 09/0900Z 16.8N 109.4W 55 KT 65 MPH 12H 09/1800Z 17.6N 110.8W 60 KT 70 MPH 24H 10/0600Z 18.6N 112.9W 65 KT 75 MPH 36H 10/1800Z 19.6N 115.3W 65 KT 75 MPH 48H 11/0600Z 20.3N 118.2W 60 KT 70 MPH 60H 11/1800Z 20.9N 121.2W 50 KT 60 MPH 72H 12/0600Z 21.1N 124.1W 45 KT 50 MPH 96H 13/0600Z 21.2N 129.7W 35 KT 40 MPH 120H 14/0600Z 21.4N 135.2W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Cangialosi

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Tropical Storm Cristina Forecast Discussion Number 10

2020-07-09 04:33:17| National Hurricane Center (East Pacific)

Issued at 900 PM MDT Wed Jul 08 2020 000 WTPZ45 KNHC 090233 TCDEP5 Tropical Storm Cristina Discussion Number 10 NWS National Hurricane Center Miami FL EP052020 900 PM MDT Wed Jul 08 2020 After the earlier convective hiatus, Cristina is now going through a little bit of a bursting phase with new inner-core convection developing just west of the center, with the latter feature showing up quite nicely in 0139 UTC SSMI/S microwave satellite imagery. The intensity has been increased to 55 kt based on satellite classifications of T3.5/55 kt from TAFB, and 57 kt and 59 kt from UW-CIMSS ADT and SATCON, respectively. Cristina is moving northwestward or 305/11 kt. The strong subtropical ridge to the north and northeast of the tropical cyclone should keep Cristina moving in that general direction tonight, followed by a turn toward the west-northwest at about the same forward speed by Thursday morning. By 96 h and beyond, a rapidly weakening and vertically shallow Cristina should turn westward under the influence of brisk easterly trade wind flow. The latest NHC model guidance remains in strong agreement on this evolving track scenario, and the new track forecast closely follows the tightly packed consensus models, which are a little south of the previous advisory track. Environmental and oceanic conditions are expected to remain conducive for strengthening during the next 36-48 h while Cristina remains over SSTs greater than 26 deg C. By 72 h and beyond, the cyclone will be moving over much cooler water characterized by SSTs near 22C by 96-120h, which is expected to induce steady weakening despite the low vertical wind shear conditions. The new NHC intensity forecast is similar to the previous advisory and the IVCN intensity consensus, with Cristina still expected to become a hurricane by late Thursday or early Friday. FORECAST POSITIONS AND MAX WINDS INIT 09/0300Z 16.4N 108.6W 55 KT 65 MPH 12H 09/1200Z 17.3N 110.0W 60 KT 70 MPH 24H 10/0000Z 18.3N 111.9W 65 KT 75 MPH 36H 10/1200Z 19.2N 114.1W 70 KT 80 MPH 48H 11/0000Z 20.0N 116.7W 70 KT 80 MPH 60H 11/1200Z 20.6N 119.6W 65 KT 75 MPH 72H 12/0000Z 21.0N 122.4W 50 KT 60 MPH 96H 13/0000Z 21.2N 127.8W 35 KT 40 MPH 120H 14/0000Z 21.6N 133.7W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart

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Tropical Storm Cristina Forecast Discussion Number 9

2020-07-08 22:50:39| National Hurricane Center (East Pacific)

Issued at 300 PM MDT Wed Jul 08 2020 000 WTPZ45 KNHC 082050 TCDEP5 Tropical Storm Cristina Discussion Number 9 NWS National Hurricane Center Miami FL EP052020 300 PM MDT Wed Jul 08 2020 Cristina is having some difficulty this afternoon in maintaining deep convection over its center. Briefly, the low-level center became apparent via GOES-16 visible imagery just north of its main convective mass. This exposed center was also confirmed by a 1756Z 37 GHz color image from the GPM satellite. The more-easily-observed center allows for a confident assessment of its northwest motion at 11 kt. Cristina should turn back to the west-northwest at about the same rate of forward speed tomorrow as a broad mid-level ridge builds north of the tropical storm. That motion should continue for the next few days until Cristina turns to the west and accelerates slightly as its remnant low is steered by the near-surface trade winds. The global and hurricane dynamical models are in close agreement on this forecast track, which is slightly north of the previous advisory due to the more northward initial position of Cristina. The Dvorak classifications from SAB and TAFB not changing at 18Z as well as the partially exposed center indicate that the earlier intensification has temporarily ceased. A 50-kt maximum wind remains the current intensity, though the ASCAT-A pass and SATCON satellite consensus suggests that this may be somewhat generous. Conditions are quite conducive for intensification in the short term, as SSTs are above 28C, mid-level humidity is near 75 percent, and deep tropospheric vertical shear is only 5-10 kt. However, the SSTs are already cooling along the track of Cristina and it should pass over the 27C SST isotherm in about 36-48 hours. After 48 hours, the thermodynamic components quickly become hostile for the system. The statistical and mesoscale hurricane models have backed off some more and the peak intensity has been lowered slightly compared to the previous advisory. It does appear that the opportunity for Cristina to rapidly intensify is diminishing. Cristina is expected to become a remnant low in four to five days, once deep convection ceases. The aforementioned ASCAT-A scatterometer pass confirmed the rather small size - 60 nm maximum wind radii in the southeastern quadrant - of Cristina this afternoon. Only a modest increase in size is expected over the next couple of days based on the RVCN consensus technique. FORECAST POSITIONS AND MAX WINDS INIT 08/2100Z 16.0N 107.7W 50 KT 60 MPH 12H 09/0600Z 17.0N 109.0W 55 KT 65 MPH 24H 09/1800Z 18.0N 111.0W 60 KT 70 MPH 36H 10/0600Z 18.9N 113.0W 65 KT 75 MPH 48H 10/1800Z 19.8N 115.3W 70 KT 80 MPH 60H 11/0600Z 20.6N 118.1W 65 KT 75 MPH 72H 11/1800Z 21.1N 120.8W 55 KT 65 MPH 96H 12/1800Z 21.5N 126.2W 40 KT 45 MPH 120H 13/1800Z 22.0N 132.0W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ Forecaster Landsea

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