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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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