CRISTOBAL heads Out to Sea / Invest 98 in GOM / Disturbance approaches CARIB

(By Steve Gregory - Subbing for Dr. Masters who is on Vacation.)

HURRICANE CRISTOBAL

CRISTOBAL is located about 360NM SE of Cape Hatteras moving North at around 11Kts. The storm remains a minimal hurricane with sustained surface winds around 65Kts. ALL models call for the storm to turn NNE and then NE at an accelerated pace as an upper air, mid-latitude TROF moves into the Northeastern US. While the storm may see some additional intensification from the high level divergent flow ahead of the NE U.S. TROF and associated baroclinic forcing – the storm will be transitioning rather quickly tomorrow to an extratropical storm as it heads northeast into the NORATL shipping lanes. (I for one am glad to see this extremely tough system to forecast departing our area of interest!)

INVEST 98L and ‘EX INVEST 97L’

While NHC dropped 97L early yesterday – it added INVEST 98L earlier this morning. INVEST 98L in the NW GOM originated at the ‘tail end’ of a very strong mid-level Dry Line that surged south/southwest from the SE US across Florida and into the northern Gulf of Mexico (GOM) 2 days ago – triggering a line of very strong T-storms along and ahead of it. While the dry line boundary has begun to fade away (though relatively dry air continues to dominate much of the GOM) a small surface circulation has formed in the NW GOM, centered about 200NM east of Corpus Christi, TX. An area of convection, with some isolated deep convection, is near and to the North and Northeast of the Low itself. The convection and surface circulation is quasi-stationary, and with wind shear of 30Kts over most of the system, significant development is unlikely for at least the next 24 hours. The first run of specialized tropical cyclone models (12Z cycle) are in remarkably good agreement on forecasting the system to move slowly westward into south Texas in 48-72 hours. With a generally anti-cyclonic flow aloft, and some of the warmest SST’s seen in years in this part of the GOM, and falloff in wind shear to under 15Kts could allow this small disturbance to spin-up prior to moving inland. That said - I doubt the system could ever develop beyond depression intensity.

' EX INVEST 97L' STILL WORTH WATCHING’

While yesterday’s Global model runs had forecast what was 97L to develop into a significant cyclone, the last few runs have completely backed away on this. However, most of the global models now forecast this elongated wave near the eastern CARIB to move across the CARIB towards the Yucatan over the weekend, with some models showing a small cyclone formation in the southern GOM next week.

There has been a dramatic increase in moisture both with the westbound wave and with a moisture plume from the deep (Equatorial) tropics in South America (SOAMER) that has been surging northward ahead of the wave for over 24 hours. Though wind shear is over 30Kts over much of the eastern CARIB (and will remain relatively high for the next few days) there is a somewhat anti-cyclonic flow developing between a small upper air Low/TROF in the west central CARIB and the approaching T.W. in the far eastern CARIB. This anti-cyclonic curvature of the high level wind field may develop further and move westward as the tropical wave traverses the CARIB over the next few days – and shear speeds may drop off during the weekend. Clearly a system worth monitoring over the coming days.

STRONG DISTURBANCE STILL WESTBOUND OVER AFRICA

One of the season's strongest ‘Cape Verde’ disturbances is emerging off the West African coast, with virtually all global models forecasting the system to gradually intensify over the weekend as it heads West/Northwest. This strong wave with a cyclonic circulation field has a long history since it developed in the highlands of east-central Africa last weekend and has maintained a low-mid level circulation and significant convection as it crossed north Africa. The most reliable models (especially the GFS) have consistently shown this system developing into a strong cyclone this weekend and early next week – but also shows the system turning Northwestward and eventually northward as it approaches the central Atlantic. The latest (12Z GFS) model run has shown this recurvature occurring a bit further west than earlier runs - but the ‘theme’ of ultimately turning this system out to sea before it can impact the CARIB or US remains unchanged.

ONCE POWERFUL HURRICANE MARIE POUNDING CALIFORNIA COAST WITH LARGE SWELLS

Hurricane MARIE should soon be downgraded to a Tropical storm – and then Depression - within 24 hours as the storm’s rapidly warming cloud tops clearly indicate the storm is moving over much cooler SST’s (under 24°C). The storm is about 900NM SW of Los Angeles and continues to move W/NW at about 13Kts, and will turn more Northwestward in 24-36 hrs and gradually fade away.

The very large and damaging swells from Marie along the Baja and southern CA coast beaches (and to a lessor degree, the original wave action from Karina which became coherent with the large swells from Marie) appear to have peaked this morning, with reported swell heights overnight reaching 10-15 feet, and isolated 20ft heights in some ‘coves’ along the south/southwest facing beach’s. The NWS has maintained advisories for beaches from Ventura to San Diego for “damaging high surf, very strong rip currents and minor coastal flooding.” The LAX areas expecting the highest surf are Long Beach through the Palos Verdes Peninsula, including Cabrillo Beach and Point Fermin, as well as Malibu and Zuma beaches. The biggest waves are expected to hit in Orange County, especially the Huntington and Newport Beach areas. Wave heights should gradually decline over the next 48 hours, with heights expected to fall off to near normal on Saturday.



Fig 1: Early morning imagery shows departing CRISTOBAL, along with the small Low pressure area in the far NW GOM (INVEST 98L) - the large, elongated Tropical Wave near the eastern CARIB (EX 97L) – and the strong tropical wave/Low near the west African coast. The forecast tracks for these system are based on the consensus of the 00Z Global Model solutions and the 12Z Early Model runs in the case of 98L.



Fig 2: The above Water Vapor image from earlier this AM shows a small convective ‘ball’ with isolated deep convection, and a surface Low that is INVEST 98L. This formed at the tail end of a remarkably strong ‘Dry Line’ that pushed S/SW into the northern GOM 2 days ago. Much of the Gulf remains under a very dry environment – in stark contrast to the rapidly moistening CARIB as a moisture plume continues to develop in the central CARIB along with expansive moisture (and isolated to scattered deep convection) associated with the elongated Tropical Wave in the far eastern CARIB. Based on imagery loops, moisture from the ITCZ south of the Tropical Wave also appears to be moving northward towards the wave itself.



Fig 3: The early morning wind shear analysis shows high shear values of 30Kts+ over 98L and 20-30Kts over the eastern CARIB. There is a chance that the anti-cyclone over the central GOM may shift further northward allowing shear values to fall, allowing for a more favorable venting environment for the system to develop before it moves inland on Saturday.



Fig 4: Should atmospheric conditions become more favorable for development for 98L, SST’s of 30°C or higher will certainly provide more than enough energy for quick development.



Fig 5: The IR image with satellite derived winds shows the still quite strong Tropical Low/Wave complex emerging off the West African coast. It also shows the large convective complex that was over east Africa that developed just west of southernmost Saudi Arabia several days ago. However, unlike the leading wave near the Cape Verdes, the central African wave does not have a well defined rotation – though a fairly strong African Easterly Jet (AEJ) with E/NE winds over 60Kts (not shown) from south of Saudi Arabia and nosing east/southeast into the central African Wave, may yet help to develop this wave. At this point though, none of the models show significant development of this system.



Fig 6: Hurricane MARIE is weakening rapidly, but the large swells generated by the storm earlier this week continue to move into the Baja and southern CA coast. Offshore Buoys show swells heights of 8-11 ft. However, under water topography – and the possibility of ‘rogue’ waves - mean swell heights could still reach 20+ ft along some southern CA locations today and early tonight before swell wave train heights lower significantly.

The next update will be by Dr. Jeff Masters tomorrow.

For those interested , you can follow my Tropical updates on my own blog tomorrow (located Here).

Steve Gregory