ERIKA ‘Gone’ as Hurricane IGNACIO Threatens Hilo
SUNDAY, 30AUG15 / 6:20 PM CDT
RETURNING TO NORMAL WX UPDATE SCHEDULE STARTING WEDNESDAY ASSUMING
THERE ARE NO UNEXPECTED TROPICAL DEVELOPMENTS
REMNANTS OF ERIKA BRING LOCALLY HEAVY RAINS TO FLORIDA
While T.S. ERIKA dissipated early yesterday as was generally expected, locally heavy & possibly flooding rains and gusty winds from the remnants of the cyclone will continue to impact much of Florida during the next 48 hours. With an upper Low along the northern Gulf coast expected to persist through much of the week, widespread shower and T-storm activity is likely to continue across much of the Gulf coast region during the week ahead.
HURRICANE IGNACIO WEAKENS BUT REMAINS A THREAT TO HAWAII EVEN AS IT IS LIKELY TO
PASS NORTH OF THE ISLANDS TUESDAY
What was Major Hurricane Ignacio is now about 400NM east of Hilo, with MAX sustained surface winds now down to around 90Kts. RECON data last night reported Max Flite Level winds of 126Kts with a central pressure near 941mb – a ‘solid’ CAT 4 Hurricane - with a thermal eye-wall Temp differential of 10˚C. However, the latest RECON within the past 2 hours reported the eye-wall had opened up in the SE sector, the pressure had risen to 960mb, and the Max Flite level winds had fallen to 107 Kts. The significant degradation in the storm’s satellite signature and other RECON reported metrics strongly suggests IGNACIO has weakened to a CAT 2 storm as west-southwest shear has begun to take its toll on the storm’s inner core structure.
The Hurricane models and GFS have all been very consistent in showing the storm staying on a NW course – and should pass about 200NM north of the Islands on Tuesday – and will likely be down to a strong Tropical Storm Intensity as progressively stronger wind shears should impact the storm as it progresses towards the Islands.
MAJOR HURRICANE JIMENA NOT SEEN AS A THREAT TO HAWAII BUT ITS REMNANTS
MAY FIND ITS WAY TO THE WEST COAST OF NORTH AMERICA IN 10-15 DAY
MAJOR CAT 4 Hurricane JIMENA located about midway between Hawaii and Baja, California with estimated 120Kt winds is heading WNW at 13 Kts, and should begin recurving towards the NW by the end of the week as the sub-tropical ridge that extends from northern Mexico westward to north of the storm weakens and the remarkably strong TROF off the PAC NW coast digs south. With cooler ocean Temps ahead and increasing wind shear – this storm is also expected to weaken as the week progresses – probably falling to below hurricane force by next weekend. The global models continue to ‘pick up’ on this system – eventually turning it Northeast and merging it with an approaching frontal boundary in about 10-12 days – possibly bringing heavy rains and isolated storm force winds to some locations along the west coast of North America.
REMEMBER KILO?
Once Tropical Depression KILO passed west of Hawaii – we ‘all’ lost interest in what was to become a Major Hurricane. The CAT 4 Hurricane is now near the Dateline, roughly 1,200NM West of Hawaii, drifting Northward – though the latest model runs have the storm turning westward again later Monday. ALL intensity models keep KILO as a CAT 4 Hurricane through the week.
TROPICAL STORM ‘FRED’ NEAR THE CAPE VERDES
The very strong Tropical Wave/Low that we’ve been following across Africa since last week came off the African coast yesterday morning and is now Tropical Storm FRED with estimated sustained surface winds of around 45 Kts. The storm is expected to move Northwest across the Cape Verdes during the next 24-48 hrs and intensify to near Hurricane intensity before it begins to weaken as it comes under the increasing influence of the SAL and higher wind shear by mid-week. All models show the storm eventually heading out to sea – and it could dissipate by next weekend.
UNSEASONABLY WARM TEMPS FROM THE ROCKIES EASTWARD
As the large scale TROF in the east weakens, a very strong TROF has moved into the PAC NW with storm force winds and locally heavy rains near the coast last night. At the same time, upper level heights are rising across the rest of the country, and this will bring unseasonably warm Temps from the Rockies to east coast during the week ahead.
With the polar jet stream bringing winds of over 160Kts in the Gulf of Alaska – more typical of mid-winter than the end of summer – the TROF over the EPAC will persist into the start of Week 2 before finally weakening. As it starts to weaken, it will eject out a series of short wave TROFS eastward across the northern US, weakening the broad upper level high and allowing the development of a deeper TROF in the northeastern US. This will bring cooler Temps to the central and eastern US during Week 2.
**
CLICK IMAGE to Open FULL size image in a new window
Fig 1: IR (Infra-Red) Satellite image of the Tropical Atlantic The remnants of ERIKA continues to fire up locally heavy T-Storm activity from near Cuba northward across Florida, while Tropical Storm FRED can be seen near the Cape Verdes Islands off the west African coast. Dry and stable air – the hallmark feature of the entire hurricane season this year - along with high wind shear – continues to dominate much of the tropical Atlantic basin, with the Tropical Wave in the central Atlantic having no chance of development.
Fig 2: Satellite derived upper level wind analysis from CIMSS for the ATL basin shows the unseasonably deep upper level Low and TROF in the GOM, with remnant moisture from ERIKA streaming northward across Florida ahead of the TROF. The complex upper Low over the central Atlantic extending SW to the CARIB – and an upper level High/ridge to its East is leading to a fairly chaotic upper level wind pattern, from the central Atlantic westward across the CARIB. While shears (not shown) are relatively light along 40˚W longitude, the air is remarkably stable – and hostile to tropical cyclone formation.
Fig 3: Satellite derived upper level wind analysis from CIMSS for the EPAC Three MAJOR Hurricanes simultaneously in the CPAC/EPAC basin - a 'first' as far as I know – with KILO in the far west, IGNACIO approaching Hawaii, and JIMENA near 130˚W longitude, Note the upper level High’s that are sitting atop each Hurricane, providing the outflow for the air rushing into the storm near the surface. To the north – jet stream winds over 160Kts are streaming across the GOA over the top of the large upper High south of the Aleutians (another highly uncommon location for a HIGH). The strong jet stream winds are digging southeastward into a deep, upper Low and TROF off the west coast of Canada southward to just west of the California coast. Eventually, the digging TROF is expected to 'pick-up' the remnant moisture and vorticity from JIMENA, sending it 'somewhere' into the west coast of North America in 10-14 days.
Fig 4: IR (Infra-Red) image of IGNACIO when it was near its peak intensity of 941mb early this AM. The perfectly clear skies within the eye of the storm are a result of the warm, sinking air emanating from the High pressure/anti-cyclone that sits atop the storm’s eye.
Fig 5: Satellite Derived Low Level winds from CIMSS. via ‘radar’ and Micro-wave sensors. Even with the relatively high resolution of the SAT sensors – it is unable to resolve the extreme wind speeds near the eyewall – which RECON reported were over 120Kts this AM. Nonetheless – this type of satellite derived information has greatly helped to improve Hurricane forecasts over the past 15 years.
Fig 6: CPHC (Central Pacific Hurricane Center) chart showing the probability of Storm Force Winds during the next 5 days. The effects of both IGNACIO and JIMENA can be seen – with the Big Island given a 30% chance of experiencing Storm force winds.
Fig 7: Tropical Cyclone Track and Intensity Forecast chart for IGNACIO from the US NAVY. The track and intensity forecasts closely follow the model consensus forecasts, with the storm expected to pass ~180NM north of Hilo and 250NM north of Honolulu as a strong Tropical Storm on Tuesday.
Fig 8: IR (Infra-Red) Image of Intensifying Hurricane JIMENA Early morning VIS image of JIMENA – while not quite as strong as it was yesterday, the storm still has CAT 4 winds. The eye was becoming cloud-filled, suggesting some type of weakening – but this was NOT really the case. (See next Fig.)
Fig 9: MICRO-WAVE Image of JIMENA taken a few hours before the above VIS image – shows JIMENA with 2 and possibly 3 eye-walls! This occurs with powerful hurricanes as they undergo Eye-wall Replacement Cycles (ERC). Intense hurricanes partially derive their strong winds as the eye of the cyclone slowly shrinks down. (This phenomena will be discussed in a very short ‘course’ on Hurricanes I’ll be posting hopefully later this week - time permitting.) Eventually, the eye gets ‘too small’ – and the storm develops an outer eye wall ring, with the inner eye wall eventually dissipating. This ‘cycling’ of eye-walls was captured on this early AM image, with the brighter ‘red tones’ associated with the intense eye walls. But as this process unfolds, storm intensity varies - falling off before it re-strengthens once the ERC completes.
Fig 10: VISIBLE ‘True-Color’ Image of T.S. FRED from the MODIS Satellite imagingThis 1KM REZ image from earlier today shows the remarkably well developed cyclone we began tracking when it was still over central Africa last TUES. You can clearly see the strong T-Storms wrapping around the centroid of the storm’s circulation field – along with the dust-filled air within the SAL that came along with the storm as it emerged off the coast yesterday. Despite the warm waters and amazing well-developed circulation, the storm is already heading Northwestward (a more typical heading at the end of SEP – not at the seasonal ‘peak’ which is where we are now). By Tuesday, FRED will likely start ingesting the dry & dusty air associated with the SAL. This, combined with the cooler SST’s to the northwest and higher wind shears – should start the weakening process, and the cyclone could become a depression by next weekend.
Fig 11: Color Enhanced IR image of FRED with Shear analysis overlay. While the dry and stable SAL air will be the primary cause for the anticipated weakening of FRED – wind shear of over 20Kts will likely ensure the storm weakens to a depression – or even dissipates – by next weekend. However, until mid-week, it's advisable to closely monitor this storm as any strengthening of the sub-tropical ridge to its north could turn the storm towards the west – potentially changing the environmental dynamics for the storm later this week..
Fig 12: Satellite derived wind field around FRED. This chart is created using a variety of satellite ‘radar & micro-wave’ based imaging sensors. While these charts can be used for wind analysis over land – their primary use is for over-water analysis where the ‘friction layer’ is much shallower (under 1,000’ vs 3,000’+ over ‘flat’ land). In this case, sustained near surface winds of tropical storm intensity (39Kts) allowed NHC to upgrade the system to Tropical Storm FRED.
Fig 13: NHC Track/Intensity forecast for FRED. Evidently, the NAVY took the day off (just kidding) – so their Track forecast Chart wasn’t available today. Instead - we have the NHC chart...
Fig 14: Temperature ANOMALY forecast for Week 1 is based STRICTLY on the MOS data forecasts from the todays 12Z operational GFS model run with minor adjustments towards the raw model data points. WARM Temps will overspread the entire eastern US this week as cooler than normal Temps dominate much of the west. Confidence in the forecast anomaly Pattern and magnitude is still above average with reading of ‘4’ for the anomaly pattern, and ‘3’ for the anomaly magnitude on a Scale from 1 to 5.
Fig 15: Running Precipitation totals for US during the next 10-days (and only for totals > 0.75”) based STRICTLY on the GFS A wet week likely for the immediate Gulf coast region as the remnants of ERIKA and a moist tropical flow envelopes the region. A band of heavier Precip across the Rockies will come from the combined effects of the summer monsoon and the relatively strong cold front dividing the nation - with warm air to the east - and cooler air in the west.
Fig 16: The Week 2 Temperature ANOMALY forecast is based on the 12Z run of the GFS (80%) integrated with the 12Z GFS Ensemble (20%) using the projected pattern along with explicit surface and 850mb (~5,000 FT) Temp forecasts. Some Temps are adjusted for known / expected anomalous thermal patterns & projected storm system passages.As the TROF in the EPAC weakens a bit, a new TROF will start developing in the east - bringing cooler conditions to the east during Week 2. Overall Confidence in the forecast anomaly Pattern and magnitude is near average for this time of year.
✭ RETURNING TO NORMAL WX UPDATE SCHEDULE STARTING MONDAY ASSUMING THERE ✭
ARE NO UNEXPECTED TROPICAL DEVELOPMENTS✭
Want to be alerted when I post an Update? Then follow me on Twitter!
Steve
SUNDAY, 30AUG15 / 6:20 PM CDT
RETURNING TO NORMAL WX UPDATE SCHEDULE STARTING WEDNESDAY ASSUMING
THERE ARE NO UNEXPECTED TROPICAL DEVELOPMENTSREMNANTS OF ERIKA BRING LOCALLY HEAVY RAINS TO FLORIDA
While T.S. ERIKA dissipated early yesterday as was generally expected, locally heavy & possibly flooding rains and gusty winds from the remnants of the cyclone will continue to impact much of Florida during the next 48 hours. With an upper Low along the northern Gulf coast expected to persist through much of the week, widespread shower and T-storm activity is likely to continue across much of the Gulf coast region during the week ahead.
HURRICANE IGNACIO WEAKENS BUT REMAINS A THREAT TO HAWAII EVEN AS IT IS LIKELY TO
PASS NORTH OF THE ISLANDS TUESDAY What was Major Hurricane Ignacio is now about 400NM east of Hilo, with MAX sustained surface winds now down to around 90Kts. RECON data last night reported Max Flite Level winds of 126Kts with a central pressure near 941mb – a ‘solid’ CAT 4 Hurricane - with a thermal eye-wall Temp differential of 10˚C. However, the latest RECON within the past 2 hours reported the eye-wall had opened up in the SE sector, the pressure had risen to 960mb, and the Max Flite level winds had fallen to 107 Kts. The significant degradation in the storm’s satellite signature and other RECON reported metrics strongly suggests IGNACIO has weakened to a CAT 2 storm as west-southwest shear has begun to take its toll on the storm’s inner core structure.
The Hurricane models and GFS have all been very consistent in showing the storm staying on a NW course – and should pass about 200NM north of the Islands on Tuesday – and will likely be down to a strong Tropical Storm Intensity as progressively stronger wind shears should impact the storm as it progresses towards the Islands.
MAJOR HURRICANE JIMENA NOT SEEN AS A THREAT TO HAWAII BUT ITS REMNANTS
MAY FIND ITS WAY TO THE WEST COAST OF NORTH AMERICA IN 10-15 DAY MAJOR CAT 4 Hurricane JIMENA located about midway between Hawaii and Baja, California with estimated 120Kt winds is heading WNW at 13 Kts, and should begin recurving towards the NW by the end of the week as the sub-tropical ridge that extends from northern Mexico westward to north of the storm weakens and the remarkably strong TROF off the PAC NW coast digs south. With cooler ocean Temps ahead and increasing wind shear – this storm is also expected to weaken as the week progresses – probably falling to below hurricane force by next weekend. The global models continue to ‘pick up’ on this system – eventually turning it Northeast and merging it with an approaching frontal boundary in about 10-12 days – possibly bringing heavy rains and isolated storm force winds to some locations along the west coast of North America.
REMEMBER KILO?
Once Tropical Depression KILO passed west of Hawaii – we ‘all’ lost interest in what was to become a Major Hurricane. The CAT 4 Hurricane is now near the Dateline, roughly 1,200NM West of Hawaii, drifting Northward – though the latest model runs have the storm turning westward again later Monday. ALL intensity models keep KILO as a CAT 4 Hurricane through the week.
TROPICAL STORM ‘FRED’ NEAR THE CAPE VERDES
The very strong Tropical Wave/Low that we’ve been following across Africa since last week came off the African coast yesterday morning and is now Tropical Storm FRED with estimated sustained surface winds of around 45 Kts. The storm is expected to move Northwest across the Cape Verdes during the next 24-48 hrs and intensify to near Hurricane intensity before it begins to weaken as it comes under the increasing influence of the SAL and higher wind shear by mid-week. All models show the storm eventually heading out to sea – and it could dissipate by next weekend.
UNSEASONABLY WARM TEMPS FROM THE ROCKIES EASTWARD
As the large scale TROF in the east weakens, a very strong TROF has moved into the PAC NW with storm force winds and locally heavy rains near the coast last night. At the same time, upper level heights are rising across the rest of the country, and this will bring unseasonably warm Temps from the Rockies to east coast during the week ahead.
With the polar jet stream bringing winds of over 160Kts in the Gulf of Alaska – more typical of mid-winter than the end of summer – the TROF over the EPAC will persist into the start of Week 2 before finally weakening. As it starts to weaken, it will eject out a series of short wave TROFS eastward across the northern US, weakening the broad upper level high and allowing the development of a deeper TROF in the northeastern US. This will bring cooler Temps to the central and eastern US during Week 2.
**
CLICK IMAGE to Open FULL size image in a new window
Fig 1: IR (Infra-Red) Satellite image of the Tropical Atlantic The remnants of ERIKA continues to fire up locally heavy T-Storm activity from near Cuba northward across Florida, while Tropical Storm FRED can be seen near the Cape Verdes Islands off the west African coast. Dry and stable air – the hallmark feature of the entire hurricane season this year - along with high wind shear – continues to dominate much of the tropical Atlantic basin, with the Tropical Wave in the central Atlantic having no chance of development.
Fig 2: Satellite derived upper level wind analysis from CIMSS for the ATL basin shows the unseasonably deep upper level Low and TROF in the GOM, with remnant moisture from ERIKA streaming northward across Florida ahead of the TROF. The complex upper Low over the central Atlantic extending SW to the CARIB – and an upper level High/ridge to its East is leading to a fairly chaotic upper level wind pattern, from the central Atlantic westward across the CARIB. While shears (not shown) are relatively light along 40˚W longitude, the air is remarkably stable – and hostile to tropical cyclone formation.
Fig 3: Satellite derived upper level wind analysis from CIMSS for the EPAC Three MAJOR Hurricanes simultaneously in the CPAC/EPAC basin - a 'first' as far as I know – with KILO in the far west, IGNACIO approaching Hawaii, and JIMENA near 130˚W longitude, Note the upper level High’s that are sitting atop each Hurricane, providing the outflow for the air rushing into the storm near the surface. To the north – jet stream winds over 160Kts are streaming across the GOA over the top of the large upper High south of the Aleutians (another highly uncommon location for a HIGH). The strong jet stream winds are digging southeastward into a deep, upper Low and TROF off the west coast of Canada southward to just west of the California coast. Eventually, the digging TROF is expected to 'pick-up' the remnant moisture and vorticity from JIMENA, sending it 'somewhere' into the west coast of North America in 10-14 days.
Fig 4: IR (Infra-Red) image of IGNACIO when it was near its peak intensity of 941mb early this AM. The perfectly clear skies within the eye of the storm are a result of the warm, sinking air emanating from the High pressure/anti-cyclone that sits atop the storm’s eye.
Fig 5: Satellite Derived Low Level winds from CIMSS. via ‘radar’ and Micro-wave sensors. Even with the relatively high resolution of the SAT sensors – it is unable to resolve the extreme wind speeds near the eyewall – which RECON reported were over 120Kts this AM. Nonetheless – this type of satellite derived information has greatly helped to improve Hurricane forecasts over the past 15 years.
Fig 6: CPHC (Central Pacific Hurricane Center) chart showing the probability of Storm Force Winds during the next 5 days. The effects of both IGNACIO and JIMENA can be seen – with the Big Island given a 30% chance of experiencing Storm force winds.
Fig 7: Tropical Cyclone Track and Intensity Forecast chart for IGNACIO from the US NAVY. The track and intensity forecasts closely follow the model consensus forecasts, with the storm expected to pass ~180NM north of Hilo and 250NM north of Honolulu as a strong Tropical Storm on Tuesday.
Fig 8: IR (Infra-Red) Image of Intensifying Hurricane JIMENA Early morning VIS image of JIMENA – while not quite as strong as it was yesterday, the storm still has CAT 4 winds. The eye was becoming cloud-filled, suggesting some type of weakening – but this was NOT really the case. (See next Fig.)
Fig 9: MICRO-WAVE Image of JIMENA taken a few hours before the above VIS image – shows JIMENA with 2 and possibly 3 eye-walls! This occurs with powerful hurricanes as they undergo Eye-wall Replacement Cycles (ERC). Intense hurricanes partially derive their strong winds as the eye of the cyclone slowly shrinks down. (This phenomena will be discussed in a very short ‘course’ on Hurricanes I’ll be posting hopefully later this week - time permitting.) Eventually, the eye gets ‘too small’ – and the storm develops an outer eye wall ring, with the inner eye wall eventually dissipating. This ‘cycling’ of eye-walls was captured on this early AM image, with the brighter ‘red tones’ associated with the intense eye walls. But as this process unfolds, storm intensity varies - falling off before it re-strengthens once the ERC completes.
Fig 10: VISIBLE ‘True-Color’ Image of T.S. FRED from the MODIS Satellite imagingThis 1KM REZ image from earlier today shows the remarkably well developed cyclone we began tracking when it was still over central Africa last TUES. You can clearly see the strong T-Storms wrapping around the centroid of the storm’s circulation field – along with the dust-filled air within the SAL that came along with the storm as it emerged off the coast yesterday. Despite the warm waters and amazing well-developed circulation, the storm is already heading Northwestward (a more typical heading at the end of SEP – not at the seasonal ‘peak’ which is where we are now). By Tuesday, FRED will likely start ingesting the dry & dusty air associated with the SAL. This, combined with the cooler SST’s to the northwest and higher wind shears – should start the weakening process, and the cyclone could become a depression by next weekend.
Fig 11: Color Enhanced IR image of FRED with Shear analysis overlay. While the dry and stable SAL air will be the primary cause for the anticipated weakening of FRED – wind shear of over 20Kts will likely ensure the storm weakens to a depression – or even dissipates – by next weekend. However, until mid-week, it's advisable to closely monitor this storm as any strengthening of the sub-tropical ridge to its north could turn the storm towards the west – potentially changing the environmental dynamics for the storm later this week..
Fig 12: Satellite derived wind field around FRED. This chart is created using a variety of satellite ‘radar & micro-wave’ based imaging sensors. While these charts can be used for wind analysis over land – their primary use is for over-water analysis where the ‘friction layer’ is much shallower (under 1,000’ vs 3,000’+ over ‘flat’ land). In this case, sustained near surface winds of tropical storm intensity (39Kts) allowed NHC to upgrade the system to Tropical Storm FRED.
Fig 13: NHC Track/Intensity forecast for FRED. Evidently, the NAVY took the day off (just kidding) – so their Track forecast Chart wasn’t available today. Instead - we have the NHC chart...
Fig 14: Temperature ANOMALY forecast for Week 1 is based STRICTLY on the MOS data forecasts from the todays 12Z operational GFS model run with minor adjustments towards the raw model data points. WARM Temps will overspread the entire eastern US this week as cooler than normal Temps dominate much of the west. Confidence in the forecast anomaly Pattern and magnitude is still above average with reading of ‘4’ for the anomaly pattern, and ‘3’ for the anomaly magnitude on a Scale from 1 to 5.
Fig 15: Running Precipitation totals for US during the next 10-days (and only for totals > 0.75”) based STRICTLY on the GFS A wet week likely for the immediate Gulf coast region as the remnants of ERIKA and a moist tropical flow envelopes the region. A band of heavier Precip across the Rockies will come from the combined effects of the summer monsoon and the relatively strong cold front dividing the nation - with warm air to the east - and cooler air in the west.
Fig 16: The Week 2 Temperature ANOMALY forecast is based on the 12Z run of the GFS (80%) integrated with the 12Z GFS Ensemble (20%) using the projected pattern along with explicit surface and 850mb (~5,000 FT) Temp forecasts. Some Temps are adjusted for known / expected anomalous thermal patterns & projected storm system passages.As the TROF in the EPAC weakens a bit, a new TROF will start developing in the east - bringing cooler conditions to the east during Week 2. Overall Confidence in the forecast anomaly Pattern and magnitude is near average for this time of year.
✭ RETURNING TO NORMAL WX UPDATE SCHEDULE STARTING MONDAY ASSUMING THERE ✭
ARE NO UNEXPECTED TROPICAL DEVELOPMENTS✭Want to be alerted when I post an Update? Then follow me on Twitter!
Steve
No comments:
Post a Comment