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Hurricane CRISTOBAL Forecast Discussion Number 11

2014-08-26 10:37:09| National Hurricane Center (Atlantic)

Issued at 500 AM EDT TUE AUG 26 2014 000 WTNT44 KNHC 260837 TCDAT4 HURRICANE CRISTOBAL DISCUSSION NUMBER 11 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014 500 AM EDT TUE AUG 26 2014 As indicated by my predecessor, Cristobal's cloud pattern is not typical of a hurricane on IR images. The convection is quite linear and the system appears to be embedded within the tail of a frontal zone. However, an reconnaissance planes recently measured winds of 73 kt at flight level and a minimum central pressure of 987 mb. This supports an initial intensity of 65 knots. Most of the global models intensify the cyclone, and given that the shear is gradually decreasing, the NHC forecast calls for some strengthening at a rate very close to the latest intensity consensus model ICON. By day 4, Cristobal is expected to be over cooler waters losing tropical characteristics. Cristobal has been meandering during the past 12 hours or more, but recently, it has begun to move toward the north at about 10 knots. The cyclone is located at the base of a narrow mid-latitude trough, and squeezed between the Atlantic subtropical ridge and a high pressure over the United States. Most of the global models show that the flow around the western side of the Atlantic ridge will steer the cyclone northward for the next 36 hours or so. Cristobal will then encounter the mid-latitude westerlies and turn to the northeast with an increase in forward speed. The guidance in general shifted slightly to the west in the latest run due to a small expansion of the Atlantic ridge. The NHC track forecast was also adjusted slightly westward during the next 24 to 36 hours, following the multi-model consensus, and placed very close to the consensus between the EMCWF and the GFS. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 26.0N 71.9W 65 KT 75 MPH 12H 26/1800Z 28.1N 71.6W 70 KT 80 MPH 24H 27/0600Z 30.6N 71.2W 70 KT 80 MPH 36H 27/1800Z 32.6N 70.3W 80 KT 90 MPH 48H 28/0600Z 35.0N 68.0W 80 KT 90 MPH 72H 29/0600Z 41.0N 55.5W 70 KT 80 MPH 96H 30/0600Z 48.0N 40.0W 60 KT 70 MPH...POST-TROP/EXTRATROP 120H 31/0600Z 57.0N 30.0W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ Forecaster Avila

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Hurricane CRISTOBAL Forecast Discussion Number 10

2014-08-26 04:43:06| National Hurricane Center (Atlantic)

Issued at 1100 PM EDT MON AUG 25 2014 000 WTNT44 KNHC 260243 TCDAT4 HURRICANE CRISTOBAL DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014 1100 PM EDT MON AUG 25 2014 Based on a blend of SFMR, flight-level, and dropsonde wind data collected by a NOAA Hurricane Hunter aircraft a little earlier this evening, Cristobal was upgraded to a 65-kt hurricane. Similar to Hurricane Bertha earlier this year in roughly the same location, this system's cloud pattern does not resemble that of a hurricane, with little or no evidence of banding on satellite images. Some additional strengthening is expected, however, since the SHIPS guidance shows a decrease in vertical shear during the next few days, and an increase in upper-level divergence is indicated by the global models. The official intensity forecast is a little higher than the previous one, and is close to the latest LGEM guidance. The center fixes by the NOAA aircraft indicated an eastward wobble several hours ago, but recent satellite imagery hints that a slow north-northeastward motion has resumed. The initial motion estimate is a rather uncertain 030/2 kt. In spite of the erratic motion and eastward shift of the center, the track model guidance remains in good agreement that Cristobal will move along a track similar to the previous NHC forecast. Over the next couple of days, the hurricane is expected to move through a weakness between two mid-level high pressure areas. Thereafter, as Cristobal begins to enter the mid-latitude westerlies and a shortwave trough moves off the northeast United States coastline, the tropical cyclone should accelerate northeastward into the North Atlantic. The current official forecast is not much different from the previous one, and close to the GFS ensemble mean solution. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 25.1N 71.9W 65 KT 75 MPH 12H 26/1200Z 26.9N 71.5W 70 KT 80 MPH 24H 27/0000Z 29.3N 70.8W 70 KT 80 MPH 36H 27/1200Z 31.8N 70.0W 75 KT 85 MPH 48H 28/0000Z 34.0N 68.0W 75 KT 85 MPH 72H 29/0000Z 39.0N 58.0W 75 KT 85 MPH 96H 30/0000Z 45.0N 45.0W 60 KT 70 MPH...POST-TROP/EXTRATROP 120H 31/0000Z 51.0N 35.0W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch

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Hurricane MARIE Forecast Discussion Number 17

2014-08-26 04:39:43| National Hurricane Center (East Pacific)

Issued at 800 PM PDT MON AUG 25 2014 000 WTPZ43 KNHC 260239 TCDEP3 HURRICANE MARIE DISCUSSION NUMBER 17 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132014 800 PM PDT MON AUG 25 2014 Satellite data indicate that Marie has gradually been weakening. Inner-core deep convection has been slowly warming, with coldest tops now south of center. Additionally, the eye has become less defined and has cooled significantly since the last advisory. A 2210 UTC TRMM overpass shows that the hurricane has also been maintaining a classic concentric eyewall structure - a double eyewall within 60 n mi of the center, with the inner eyewall possibly in the process of collapsing. A third, less-defined eyewall was noted at around 110 n mi radius, separated by a prominent dry slot. The initial intensity for this advisory is reduced to 100 kt, based on the latest Dvorak CI numbers from SAB and the UW-CIMSS ADT. Continued slow weakening is expected in the short term due to gradually decreasing sea surface temperatures and the possibility of the current eyewall replacement evolving further. Even though the vertical shear is forecast to be light, Marie will be crossing the 26 deg C isotherm in 12-18 hours and should reach sub-24 deg C waters by 48 hours. With the thermodynamic environment worsening so quickly, near-rapid weakening is likely after about 24 hours until the cyclone becomes post-tropical by day 3. The cyclone will then continue to spin down over even cooler waters, but the remnant circulation could linger beyond the end of the forecast period. The intensity forecast has been lowered a bit relative to the previous one due mostly to the greater rate of weakening observed since the last advisory. Marie is continuing on a steady northwestward course of 305/11. Mid-level ridging extending west-southwestward from the eastern United States in the subtropical eastern Pacific should continue to steer Marie on a west-northwestward to northwestward path during the next few days. After losing its deep convection by day 3 or so, the cyclone's track should bend north-northwestward or even northward and slow down. There continues to be little change with regard to the track guidance and little in the way of modifications was made to the previous track. The new NHC track is in the center of guidance envelope and close to the multi-model consensus TVCE. Although Marie is expected to remain well offshore, very large swells will continue to affect southwestern Mexico through tonight 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 26/0300Z 19.2N 116.7W 100 KT 115 MPH 12H 26/1200Z 20.2N 118.3W 90 KT 105 MPH 24H 27/0000Z 21.3N 120.6W 75 KT 85 MPH 36H 27/1200Z 22.4N 123.0W 60 KT 70 MPH 48H 28/0000Z 23.5N 125.5W 45 KT 50 MPH 72H 29/0000Z 26.5N 130.0W 35 KT 40 MPH...POST-TROPICAL 96H 30/0000Z 29.4N 132.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 31/0000Z 30.8N 133.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Kimberlain

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Tropical Depression KARINA Forecast Discussion Number 53

2014-08-26 04:33:38| National Hurricane Center (East Pacific)

Issued at 800 PM PDT MON AUG 25 2014 000 WTPZ41 KNHC 260233 TCDEP1 TROPICAL DEPRESSION KARINA DISCUSSION NUMBER 53 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014 800 PM PDT MON AUG 25 2014 The upper-level outflow from Hurricane Marie continues to strongly shear Karina, though a persistent area of deep convection continues in the western quadrant of the cyclone. The initial intensity remains 30 kt as a blend of satellite intensity estimates from TAFB and SAB. Due to the ongoing shear, Karina is expected to degenerate into a remnant low in about 12 hours, and then be absorbed into the much larger Marie in 24-36 hours. The initial motion is 095/4. A general east-southeastward motion with some increase in forward speed is expected until the cyclone is absorbed. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 17.2N 127.3W 30 KT 35 MPH 12H 26/1200Z 16.9N 126.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 24H 27/0000Z 16.4N 125.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 27/1200Z...DISSIPATED $$ Forecaster Beven

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Tropical Storm CRISTOBAL Forecast Discussion Number 9

2014-08-25 23:16:36| National Hurricane Center (Atlantic)

Issued at 500 PM EDT MON AUG 25 2014 000 WTNT44 KNHC 252116 TCDAT4 TROPICAL STORM CRISTOBAL DISCUSSION NUMBER 9...CORRECTED NWS NATIONAL HURRICANE CENTER MIAMI FL AL042014 500 PM EDT MON AUG 25 2014 Corrected forecast motion through 72 hours Cristobal remains in a moderate shear environment with the low-level center still fully exposed on the north side of the deep convection. A recent Air Force Reserve reconnaissance flight indicated maximum 850 mb flight-level winds of 65 kt in the southeast quadrant where SFMR winds of 51 kt were noted, and the central pressure has remained at 993 mb. Based on these data, the initial intensity has been held at 50 kt. Aircraft fixes indicate that Cristobal is now moving at a more reliable north-northeastward motion of 020/04 kt. There is no significant change to the previous forecast track or reasoning. The latest NHC model guidance continues to be in excellent agreement on the subtropical ridge to the north of Cristobal slowly eroding due to a strong mid/upper-level trough just off the U.S. southeast coast continuing to dig southward as noted in water vapor imagery. The combination of increasing southwesterly flow on the east side of the trough and a building ridge to the south of the cyclone should act to lift Cristobal slowly northeastward over the next 72 hours. After that, Cristobal is forecast to become embedded in deep mid-latitude westerlies and accelerate off to the northeast and east-northeast, becoming a large and powerful extratropical cyclone over the far north Atlantic by 120 hours. The official forecast track is essentially just an update of the previous advisory track, and lies just to the right of the consensus model TVCA. The shear is forecast to ebb and flow over the next 48 hours or so, and the intensity forecast has followed this trend with strengthening indicated during the periods when the vertical shear subsides. Cristobal is still expected to become a hurricane when the cyclone passes to the west and north of Bermuda on Wednesday and Thursday. On Days 4 and 5, Cristobal will be passing over much cooler waters and encountering strong southwesterly wind shear as the cyclone becomes embedded in the mid-latitude westerlies, which will result in extratropical transition by 120 hours. However, the system is likely to receive a boost from baroclinic effects, remaining as a strong extratropical cyclone. Owing to the slow motion of Cristobal, heavy rainfall and possible flooding will remain a threat for the southeastern Bahamas and the Turks and Caicos through Tuesday. Heavy rainfall is expected to continue across Bermuda through Wednesday ahead of Cristobal. FORECAST POSITIONS AND MAX WINDS INIT 25/2100Z 25.3N 72.5W 50 KT 60 MPH 12H 26/0600Z 26.6N 71.9W 55 KT 65 MPH 24H 26/1800Z 28.9N 71.2W 55 KT 65 MPH 36H 27/0600Z 31.2N 70.4W 60 KT 70 MPH 48H 27/1800Z 33.4N 68.5W 70 KT 80 MPH 72H 28/1800Z 38.1N 60.5W 65 KT 75 MPH 96H 29/1800Z 44.3N 47.3W 60 KT 70 MPH 120H 30/1800Z 51.5N 34.5W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ Forecaster Stewart

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