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Tropical Storm CRISTOBAL Forecast Discussion Number 5

2014-08-24 22:51:01| National Hurricane Center (Atlantic)

Issued at 500 PM EDT SUN AUG 24 2014 000 WTNT44 KNHC 242050 TCDAT4 TROPICAL STORM CRISTOBAL DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014 500 PM EDT SUN AUG 24 2014 Cristobal's convective cloud pattern has not changed much during the past 6 hours, other than cloud tops having warmed some. Aircraft and satellite data indicate that the inner-core wind field is still broad, with multiple small swirls rotating around a mean center. Air Force Reserve and NOAA reconnaissance aircraft data indicate the central pressure has remained steady at 1001 mb, so the initial intensity will be kept at 40 kt for this advisory. The initial motion is northward or 360/7 kt. The NHC model guidance has come into much better agreement on this cycle with the GFS track having shifted westward and the ECMWF model having shifted eastward. The rest of the models are reasonably close to the GFS and ECMWF solutions. There is one main difference, however, which is the track speed, with the GFS model lagging behind the ECMWF model and some of the other models by more than 500 n mi at 120 hours. Cristobal is expected to continue moving northward through a weakness in the subtropical ridge and slow down over the next 72 hours as a strong upper-level trough east of North Carolina lifts out to the northeast. A second trough currently over the upper Midwest is forecast to dig southeastward along the U.S. east coast by Days 4 and 5 and accelerate the cyclone northeastward over the north Atlantic. The official forecast track has been shifted eastward through 72 hours, and then shows a faster forward speed similar to the ICON consensus model at 96 and 120 hours. Light to moderate northwesterly to northerly shear is forecast to affect Cristobal through 72 hours, which should allow for only slow strengthening to occur. When Cristobal makes a northeastward turn and accelerates after that time, the shear is expected to decrease while the cyclone is over near-29C SST, which should allow Cristobal to strengthen into a hurricane. The NHC intensity forecast is similar to the previous advisory, and closely follows the consensus intensity model ICON. FORECAST POSITIONS AND MAX WINDS INIT 24/2100Z 24.5N 73.0W 40 KT 45 MPH 12H 25/0600Z 24.9N 73.1W 45 KT 50 MPH 24H 25/1800Z 25.7N 73.0W 50 KT 60 MPH 36H 26/0600Z 26.6N 72.8W 55 KT 65 MPH 48H 26/1800Z 28.4N 72.5W 60 KT 70 MPH 72H 27/1800Z 31.9N 71.8W 65 KT 75 MPH 96H 28/1800Z 35.0N 66.5W 70 KT 80 MPH 120H 29/1800Z 39.5N 58.0W 70 KT 80 MPH $$ Forecaster Stewart

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Hurricane MARIE Forecast Discussion Number 12

2014-08-24 22:32:01| National Hurricane Center (East Pacific)

Issued at 200 PM PDT SUN AUG 24 2014 000 WTPZ43 KNHC 242031 TCDEP3 HURRICANE MARIE DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132014 200 PM PDT SUN AUG 24 2014 Marie has developed a fairly steady-state structure, with a solid area of white (in the Dvorak satellite enhancement) surrounding a 10 n mi wide eye. Dvorak final-T numbers have risen to T7.0/140 kt from TAFB, SAB, and the objective ADT, and that value is set as the initial intensity. This makes Marie the first category 5 hurricane in the eastern North Pacific basin since Hurricane Celia in 2010. Unless Marie can develop even colder cloud tops in the convection surrounding the eye, continued strengthening is probably not likely. The SHIPS model shows additional intensification for the next 12-18 hours, but much of the contribution comes from persistence and not the environment itself. Plus, a 1709 UTC AMSU pass indicates that a secondary eyewall is already forming, making it likely that an eyewall replacement will occur during the next day or so. Therefore, fluctuations in intensity are expected in the short term, but the NHC intensity forecast keeps Marie as a major hurricane through 48 hours. After that time, the hurricane will quickly move over colder water, and it is likely to weaken to a tropical storm between day 3 and 4, and then become post-tropical by day 5. This scenario is not really different from the previous forecast, except maybe showing a little faster weakening after 48 hours in line with the most recent SHIPS and LGEM guidance. Trochoidal motions appear to be influencing Marie's recent short term movement, but the hurricane's longer-term 12-hour motion is 270/12 kt. The track guidance remains tightly clustered and insists that Marie should resume a west-northwestward or even northwestward motion in the next 12-24 hours. That general trajectory should continue through day 4, with Marie turning north-northwestward by day 5 when it reaches the western edge of the subtropical ridge. As in the previous forecast, no significant changes to the NHC track forecast were required on this advisory. Although Marie is expected to remain well off the coast of Mexico, very large swells will affect southwestern Mexico through tomorrow and much of the Pacific coast of the Baja California peninsula during the next few days. Southerly swells will also reach the coast of southern California by Tuesday, producing life-threatening surf and rip currents, as well as minor coastal flooding. FORECAST POSITIONS AND MAX WINDS INIT 24/2100Z 16.0N 112.2W 140 KT 160 MPH 12H 25/0600Z 16.6N 113.7W 140 KT 160 MPH 24H 25/1800Z 17.9N 115.4W 135 KT 155 MPH 36H 26/0600Z 19.5N 117.3W 120 KT 140 MPH 48H 26/1800Z 20.7N 119.4W 105 KT 120 MPH 72H 27/1800Z 23.0N 124.5W 70 KT 80 MPH 96H 28/1800Z 26.0N 129.0W 45 KT 50 MPH 120H 29/1800Z 29.5N 131.5W 35 KT 40 MPH...POST-TROPICAL $$ Forecaster Berg

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Hurricane MARIE Forecast Discussion Number 11

2014-08-24 16:48:27| National Hurricane Center (East Pacific)

Issued at 800 AM PDT SUN AUG 24 2014 000 WTPZ43 KNHC 241448 TCDEP3 HURRICANE MARIE DISCUSSION NUMBER 11 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132014 800 AM PDT SUN AUG 24 2014 Marie's eye has cleared out and warmed during the past few hours, with very cold convective tops surrounding the center. As a result, TAFB and SAB measured data T-numbers of 7.0/140 kt, but both were constrained by Dvorak rules and settled on final-T estimates of T6.5/127 kt. Also, a UW-CIMSS intensity estimate from a 0938 AMSU pass was 126 kt. Based on these data, Marie's initial intensity is raised to 130 kt. The 12-hour motion estimate is 285/13 kt, although Marie has actually been moving more westward during the past few hours. The hurricane is located to the south of a mid-level ridge which extends from Texas to the northern Baja peninsula, and this feature should propel Marie basically west-northwestward during the next 3-4 days. Thereafter, Marie will be located between strengthening ridging over northwestern Mexico and a weakness in the ridge leftover by Post-Tropical Cyclone Lowell, and it should begin to turn north-northwestward by day 5. There is very little spread among the track guidance, and the updated NHC forecast essentially lies between the previous forecast and the TVCE multi-model consensus, which has shifted a bit to the right beyond day 2. Intensity fluctuations are always possible once hurricanes like Marie get this strong. Assuming unforeseen internal dynamics and/or an eyewall replacement do not take over soon, the environment around Marie should be able to support a little more strengthening during the next 12-24 hours. Thereafter, slow weakening is likely until about day 3 when Marie will begin weakening more quickly over waters colder than 26C and in a more stable air mass. The new NHC intensity forecast shows a slightly higher peak intensity to account for the recent strengthening rate, but otherwise no significant changes were required. Although Marie is expected to remain well off the coast of Mexico, very large swells will affect southwestern Mexico through tomorrow and much of the Pacific coast of the Baja California peninsula during the next few days. These swells will cause dangerous life-threatening surf and rip currents. FORECAST POSITIONS AND MAX WINDS INIT 24/1500Z 16.0N 111.4W 130 KT 150 MPH 12H 25/0000Z 16.5N 112.9W 140 KT 160 MPH 24H 25/1200Z 17.6N 114.5W 135 KT 155 MPH 36H 26/0000Z 18.9N 116.2W 130 KT 150 MPH 48H 26/1200Z 20.3N 117.9W 115 KT 135 MPH 72H 27/1200Z 22.5N 122.0W 85 KT 100 MPH 96H 28/1200Z 25.5N 127.5W 55 KT 65 MPH 120H 29/1200Z 28.5N 131.0W 35 KT 40 MPH...POST-TROPICAL $$ Forecaster Berg

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Tropical Storm KARINA Forecast Discussion Number 47

2014-08-24 16:47:27| National Hurricane Center (East Pacific)

Issued at 800 AM PDT SUN AUG 24 2014 000 WTPZ41 KNHC 241447 TCDEP1 TROPICAL STORM KARINA DISCUSSION NUMBER 47 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014 800 AM PDT SUN AUG 24 2014 Karina's deep convection has expanded some this morning, and the strong temperature gradient in the infrared imagery on the east side of the cyclone has weakened. Both would be indicative of the large vertical shear diminishing some, consistent with the CIMSS analysis of 5-10 kt shear. The GFS-based SHIPS shear, on the other hand, is diagnosed as being about 20 kt. The intensity estimates widely range from 45-75 kt, depending on whether a shear or embedded center pattern is used in the Dvorak technique. The initial intensity is lowered slightly to 55 kt, but this estimate has more than the usual uncertainty. Even if the shear has subsided some currently, this should pick up more shortly as the outflow from major hurricane Marie affects Karina. The combination of strong vertical shear, marginally warm SSTs, and fairly dry air should lead to at least a gradual - if not quick - weakening of the tropical cyclone. The intensity forecast is based upon a blend of the SHIPS, LGEM, and HWRF models and is quite similar to that from the previous advisory. An ASCAT pass from late last night indicated tropical-storm-force winds extending out about 60 nm on the eastern semi-circle. The initial size is assessed the same as that previously, and a gradual reduction in tropical-storm-force wind radii is anticipated as the cyclone weakens. Karina is being steered east-northeastward at 8 kt around the large circulation of post-tropical Lowell to its north-northeast. The absence of microwave imagery over Karina and the lack of visible imagery before sunrise makes the current position and motion somewhat unclear. The steering influence of Lowell will diminish in about a day as the distance between the systems increases, and Karina should respond by slowing down and turning gradually to the east-southeast. In about two days, Karina's track will mainly be influenced by the approaching very large and strong Marie. Karina should be accelerated along toward the east until it becomes absorbed within Marie in about three to four days. The forecast track is based upon a blend of the GFS, GFDL, HWRF, and ECMWF models and is slightly faster than that issued in the previous advisory. FORECAST POSITIONS AND MAX WINDS INIT 24/1500Z 18.0N 131.4W 55 KT 65 MPH 12H 25/0000Z 18.0N 130.1W 45 KT 50 MPH 24H 25/1200Z 18.0N 128.7W 35 KT 40 MPH 36H 26/0000Z 17.8N 127.9W 30 KT 35 MPH 48H 26/1200Z 17.5N 127.3W 25 KT 30 MPH 72H 27/1200Z 16.9N 124.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 28/1200Z...DISSIPATED $$ Forecaster Landsea

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Tropical Storm CRISTOBAL Forecast Discussion Number 3

2014-08-24 10:49:58| National Hurricane Center (Atlantic)

Issued at 500 AM AST SUN AUG 24 2014 000 WTNT44 KNHC 240849 TCDAT4 TROPICAL DEPRESSION FOUR DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014 500 AM AST SUN AUG 24 2014 The satellite presentation of the tropical depression has gradually improved overnight. Convection has increased to the northeast of the center and a little more banding is noted. Although the pressure has dropped a few millibars during the past 6 to 12 hours, data from an Air Force Reserve Hurricane Hunter aircraft indicate that the cyclone remains a 30-kt tropical depression. Fixes from the aircraft yield an initial motion of 325/8 kt. The cyclone is expected to slow down and turn north-northwestward today into a break in the ridge caused by a mid- to upper-level trough that is currently moving off the U.S. east coast. This trough is forecast to dig southeastward during the next 24 to 36 hours before lifting northeastward on Tuesday. The track guidance has shifted significantly eastward this cycle, with the exception of the latest ECMWF, which is very similar to its 1200 UTC run. The eastward shift in most of the models appears to be the result of increased interaction of the cyclone with the aforementioned trough during the next 48 hours. This leads to a more north-northwestward or northward motion during the next day or so. Once the trough lifts out, most of the guidance shows a bend back toward the northwest, before the cyclone turns northward and northeast around a subtropical ridge to its east. The NHC track has been shifted eastward, but it remains along the western side of the guidance envelope out of respect for the ECMWF and continuity of the previous forecasts. The new track forecast is closest to the HWRF, but is well west of the latest multi-model consensus. Future eastward adjustments may be required if the eastward model trend continues. Given that a large spread remains in the guidance, the confidence in the track forecast remains lower than normal. Light to moderate northwesterly shear is expected during the next few days. However, the shear is not expected to be strong enough to prevent strengthening, and the official forecast calls for gradual intensification throughout the forecast period. The NHC intensity forecast is close to the SHIPS guidance and the intensity consensus ICON. FORECAST POSITIONS AND MAX WINDS INIT 24/0900Z 22.9N 73.3W 30 KT 35 MPH 12H 24/1800Z 23.7N 73.7W 40 KT 45 MPH 24H 25/0600Z 24.4N 73.9W 45 KT 50 MPH 36H 25/1800Z 25.0N 74.0W 50 KT 60 MPH 48H 26/0600Z 25.9N 74.1W 55 KT 65 MPH 72H 27/0600Z 28.5N 75.5W 60 KT 70 MPH 96H 28/0600Z 31.5N 75.0W 65 KT 75 MPH 120H 29/0600Z 34.0N 70.0W 70 KT 80 MPH $$ Forecaster Brown

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