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SW Louisiana Forecast Discussion...Tuesday's forecast went exactly according to plan. Skies were Mostly Sunny and much drier air enveloped the region. A breath fresh air was around for the early morning hours with temperatures into the 60s just about area wide. The official low at LCH was 66; this was the coolest minimum since way back in the first half of May. These readings in the mid 60s were closer to normal than the mid to upper 70s we've experienced for the majority of our long summer. Temperatures warmed up rapidly with wall to wall sunshine and the lower humidity in place. High temperatures once again continued their above normal moniker with readings in the mid to upper 90s across the forecast area. Absolutely no rainfall occurred across the area with the anomalous dry air in place. The lower dew points remain with us tonight, and this will allow for another pleasant mid-September night. Expect readings to bottom out in the mid to upper 60s; a few degrees warmer than last night. A light offshore flow will prevail with Mostly Clear skies.
The drier air will begin vacating the region on Wednesday as the current surface high pressure begins to move away, and the surface wind flow kicks around to the Gulf once again. Enter the humidity...once again! High pressure will remain in close enough proximity to keep rain chances at bay, thus no mention of rain is expected for the mid-week period. High temperatures will warm up quickly once again, and have no trouble reaching the low to mid 90s. However, it should be a few degrees cooler officially given the return of the onshore flow, but the heat index will come back into play. Higher dew points will return in the afternoon, and it will be noticeably more humid by that time. The quiet weather will continue into the overnight hours of Wednesday, but of course, the brief pleasantry to the air will be a fast fading memory as lows return to the 70s area wide. Mid 70s are expected for most locations with lower 70s North of the Hwy. 190 corridor. Not much cooling at all will occur near the coast with lows hovering around the 80 degree mark.
The forecast for the end of the week is becoming a bit more certain now given what has transpired down int the Caribbean Sea today. Rain chances will return to the forecast on Thursday as the low-levels moisten up considerably. High pressure will remain in place at the mid and upper levels, and a typical Bermuda high pattern will become re-established. Expect Thursday to feature Partly Cloudy skies with a slight chance for afternoon showers and thunderstorms scattered at random across the forecast area. A sea breeze pattern is favored given the persistent onshore flow, and the fact that the Gulf will be open for business once again. Rain chances will remain slight with the upper level ridging processes holding firm. At the same time, newly formed Tropical Storm Karl will be moving towards the Yucatan Peninsula through Wednesday, and into the Southern Gulf of Mexico on Thursday. If you remember back to yesterday, I explained that if this system developed our rain chances would remain low, but if it remained a disorganized tropical low then our rain chances would increase. That being said, any hope for a soaking rain is dwindling now as Karl has formed, and will continue gaining strength except for while its over the Yucatan. It should be a tropical storm over the Southern Gulf on Thursday.
The only effects from Karl here will be very humid conditions and a deep flow of tropical air from the Southern Gulf. It is daytime heating alone that will generate scattered activity beginning Thursday, and continuing into the weekend. Rain chances will be no higher than 20% through the weekend as high pressure aloft remains anchored over the Gulf Coastal Plain. It is this high pressure which will steer Karl safely to our South. We could stand to use the rain, but it appears as though only a lucky few will receive rain each day. Sky conditions for Friday through Sunday will be Partly Cloudy and temperatures will be above normal for the middle of September. Expect morning lows to be well into the 70s for Saturday, but by Sunday morning lows will drop a bit as some drier air filters in behind Karl. Highs will continue to reach the lower 90s, but with high humidity in place expect heat indices to be close to 100 across the area. Any rain that occurs during the day will cease and desist by the evening hours, and there will no threat of rain for all the High School Football games on Friday night. Very warm and humid conditions under Partly Cloudy skies are to be expected with temperatures in the 80s during each contest. It's a case of deja vu this weekend with similar conditions abound. Karl will be making landfall in old Mexico by Saturday, and the deep flow of tropical moisture from the Gulf will continue to surge Northward. Daytime heating will induce a few storms for both Saturday and Sunday, but it is possible that I will need to lower rain chances all together as the orientation of Karl allows high pressure to strengthen over the area. This will act as an atmospheric suppression. Similar temperatures are on the docket for this third weekend in September. Any weekend plans you have get the green light. The forecast for the LSU-Mississippi State in Baton Rouge Saturday night looks fine...just hot and humid, prepare to sweat! Temperatures will be in the 80s during the game, and in the 90s for tailgating before the game. McNeese is idle this week.
The same weather pattern carries over into next week. Typical late summer weather will continue to be the story around these parts for Monday. Still no better than a 20% chance of an afternoon shower or storm is to be expected. Skies will remain Partly Cloudy and lots of humidity will be in place. It is still possible that rain chances will be removed entirely for this period as well, but I will leave in a slight chance for now. Lows will remain just above the norm for mid-late September in the lower 70s. Afternoon highs will still reach the lower 90s with plenty of sunshine to heat up the atmosphere. An onshore flow will continues with the Bermuda high in place across a large portion of the Gulf Coastal Plain. At the end of the forecast period, not much change hangs in the balance. I will leave Tuesday's forecast as is for now, very similar to Monday. However, I should mention that by the end of the forecast period perhaps we can turn our attention to the North. Models are depicting the approaching of what may turn out to be a more significant cold front. This front, if it were to come through, would be here just beyond the scope of this forecast period. It could at least help to raise rain chances a bit if nothing else, most likely on Wednesday of next week. Timing discrepancies will dictate exactly what happens; it is conceivably possible that rain chances will need to be raised for Tuesday, but given the uncertainties this far out it is not necessary at this juncture to reflect this solution. We watch and wait for a real cold front, and watch the tropics at the same time. More on the tropics below, but it does appear that the tropics will remain active through the forecast period.
Preliminary Numbers & Zone Forecast:
LCH 68/92 74/92 75/91 0 0 0 20 0 20
LFT 67/92 73/92 75/92 0 0 0 20 0 20
BPT 70/93 75/92 75/91 0 0 0 20 0 20
AEX 63/94 68/93 71/93 0 0 0 20 0 20
POE 64/94 68/93 71/93 0 0 0 20 0 20
ARA 69/92 75/91 76/90 0 0 0 20 0 20
Today...Partly Cloudy. High 93. SSE wind 10 mph.
Tonight...Clear. Low 74. Light SSE wind.
Thursday...Partly Cloudy with a 20% chance of afternoon showers & thunderstorms. SSE wind 10-15 mph.
Thursday Night...Mostly Clear. Low 75. Light SSE wind.
Friday...Partly Cloudy with a 20% chance of afternoon showers & thunderstorms. SSE wind 10-15 mph.
Wednesday 9/15/10 Daily Planner
6a.m.
Weather: Mostly Clear
Temp: 68
Rain: 0%
Wind: E 2
9a.m.
Weather: Partly Cloudy
Temp: 78
Rain: 0%
Wind: SSE 5
Noon
Weather: Partly Cloudy
Temp: 87
Rain: 0%
Wind: SSE 8
H.I.: 90
3p.m.
Weather: Partly Cloudy
Temp: 92
Rain: 0%
Wind: SSE 10
H.I.: 95
6p.m.
Weather: Partly Cloudy
Temp: 88
Rain: 0%
Wind: SSE 10
H.I.: 92
9p.m.
Weather: Mostly Clear
Temp: 83
Rain: 0%
Wind: SSE 4
Drew's 7 Day Outlook
Wednesday
9-15-10
Low: 68
High: 92
Rain: 0%
Wind: SSE 10
H.I.: 88-93
U.V.: 11- Very High
Thursday
9-16-10
Low: 74
High: 92
Rain: 20%
Wind: SSE 10-15
H.I.: 95-100
U.V.: 10- High
Friday
9-17-10
Low: 75
High: 91
Rain: 20%
Wind: SSE 10-15
H.I.: 95-100
U.V.: 11- Very High
Saturday
9-18-10
Low: 75
High: 90
Rain: 20%
Wind: SSE 10-15
H.I.: 95-100
U.V.: 10- High
Sunday
9-19-10
Low: 72
High: 91
Rain: 20%
Wind: SSE 8-13
H.I.: 93-98
U.V.: 11- Very High
Monday
9-20-10
Low: 71
High: 90
Rain: 20%
Wind: SSE 5-10
H.I.: 93-98
U.V.: 10- High
Tuesday
9-21-10
Low: 72
High: 90
Rain: 20%
Wind: SSW 5-10
H.I.: 93-98
U.V.: 10- High
...Tropical Update...
Just look at the Atlantic basin, you can tell it is prime time. We now have 3 named storms. Igor continues to be a monster, and now his kid sister, Julia is trying to catch up with him. Julia has become a major hurricane in the Far Eastern Atlantic. Finally, the tropical wave that I've discussed for the past several days has indeed become Tropical Storm Karl, and is bearing down on the Yucatan Peninsula this morning. Of course the fact that we have three storms at once is noteworthy, but we all know the old adage...."it's not how many they are, it's where they go". That certainly applies here. It's time to take a look at each one.
Igor...This monster storm continues to intensify. It is a very impressive category 4 hurricane that now is bordering on category 5 strength. Any further strengthening, and Igor will become just that. Igor is reaping the benefits of perfect conditions for strengthening over the open waters of the Atlantic. High pressure anchored to the North of the storm is producing light winds over the top of Igor, and sea surface temperatures are more than sufficient to support strengthening. Igor should be near its climax at this point, however, some additional further strengthening can't be ruled out given the highly favorable environment. Igor continues to move WNW around the SW flank of a large Atlantic subtropical ridge, but it is nearing a weakness in said ridge, and should begin to be nudged to the NW over the next 24 hours. This will keep Igor well out over the open waters, and safely away from the Lesser Antilles. Igor will make steady headway to the NW for the next several days, and gradual weakening should take shape by Thursday as internal dynamics and some wind shear off to the NW of Igor begin to influence the cyclone. I believe Igor may very well become a category 5 briefly on Wednesday before its weakening ensues. Igor is no threat to the United States at all, but could still track very close to or over Bermuda as a strong hurricane over the weekend. It seems the most likely time for Igor to impact Bermuda will come late Saturday into Sunday. The questions remain how strong will Igor be when he affects Bermuda, and what track in relation to Bermuda will Igor take? A wobble one way or the other will likely determine the degree of adversity Bermuda will experience from Igor. Models still diverge a bit beyond 4 days in how Igor will track in relation to the small island nation. Igor should begin to feel the influence of an Atlantic trough by the end of the period, so a more Northerly motion should commence over the weekend.
Hurricane Igor Advisory
10p.m. CDT Tuesday, September 14, 2010
...Igor Intensifies...Nearing Category 5 Strength...Could Threaten Bermuda Over the Weekend in a Weakening State...
Latitude: 19.0 N
Longitude: 53.9 W
This is about 605 miles E of the Northern Leeward Islands and 1,140 miles SE of Bermuda.
Maximum Sustained Winds: 155 mph w/ higher gusts. This makes Igor a very powerful category 4 storm on the Saffir-Simpson Hurricane wind scale. Little change in strength is expected over the next 24 hours. Hurricane force winds extend outward to 45 miles from the center, and tropical storm force winds extend outward to 225 miles from the center.
Movement: WNW or 295 degrees @ 9 mph. This motion is expected to continue in the short term, with a turn to the NW by Thursday. Little change in the forward motion is expected.
Minimum Central Pressure: 27.32" or 925 mb.
Julia...Julia is cooking in the open waters of the Eastern Atlantic. This cyclone is undergoing a period of rapid intensification. If you recall it was just a budding tropical storm 24 hours ago, well now it is a fierce competitor. Julia has ramped up into a major hurricane, the season's 4th. Julia is feasting on the same ideal atmospheric conditions as her big brother, Igor. Julia should be near its peak intensity, however. An environment containing wind shear awaits Julia over the next couple of days as she begins to gain latitude and take on a more NW component of motion. Julia will be steered around the periphery of the same Atlantic subtropical ridge that is guiding Igor. Julia will be moving into an unfavorable environment by weeks' end with colder waters and the increasing shear to the North of the cyclone. Julia should start weakening by Thursday, and begin to decay beyond that time frame. It will die a slow death over the weekend. An intensity of tropical storm status is indicated by Sunday. Julia is no threat to land, and will pass safely to the East of Bermuda. It may generate some additional large swells to Bermuda and the Lesser Antilles over the next several days, but that's about it.
Hurricane Julia Advisory
10p.m. Tuesday, September 14, 2010
...Julia Rapidly Intensifies Into the Season's 4th Major Hurricane...No Threat to Land...
Latitude: 16.9 N
Longitude: 31.3 W
This is about 490 miles W of the Cape Verde Islands.
Maximum Sustained Winds: 125 mph w/ higher gusts. This is a category 3 on the Saffir-Simpson Hurricane Wind Scale. Additional strengthening is possible today, before weakening begins on Thursday. Hurricane force winds extend outward to 25 miles from the center, while tropical storm force winds extend outward to 105 miles from the center.
Movement: WNW or 295 degrees @ 9 mph. A turn to the NW and an increase in forward speed is expected later today, while a turn back to the WNW and a continued increase in forward speed is expected Thursday.
Minimum Central Pressure: 28.20" or 985 mb.
Karl...Call me Karl with a 'K'! The tropical wave that has been festering in the Caribbean for the last several days was investigated by Hurricane Hunter Aircraft Tuesday afternoon. There was enough conclusive evidence to classify the system as Tropical Storm Karl. Every now and then, there are systems that form that skip the Tropical Depression phase, and go straight to Tropical Storm status. Karl is intensifying this morning, but is also bearing down on the Yucatan Peninsula. Karl is in a favorable environment for the development, the Western Caribbean is a hotbed for development during prime time. Karl's development will be impeded later on today by its interaction with Yucatan Peninsula. Karl should move ashore as a strong tropical storm over the Southern portion of the Yucatan Peninsula later this morning. Tropical storm Karl will produce some tropical storm conditions for places such as Cancun, Cozumel, and Chetumal, Mexico. The main threats there will be heavy rain and flash flooding with minor storm surge flooding. Karl will not be a major storm for that area, but a big inconvenience. Karl is being steered WNW around the Southern edge of a large anti-cyclone over the Gulf Coast states. The overall structure of Karl hasn't changed in the past 12 hours, and the forecast philosophy remains the same as well.
Karl will make its landfall over the Yucatan later today, and then quickly advance across Southern Mexico before emerging into the warm waters of the Southern Gulf of Mexico sometime on Thursday. Karl, of course, will weaken over the Yucatan as it will be cut off from its breeding ground. However, the environment over the Gulf is one that favors re-intensification. The only question is how intact will the center of circulation be as it emerges into the Gulf. Given the expected swift motion, Karl should emerge with its center intact , but as a Tropical Depression. Karl may slow down a bit over land, due to the typical friction that interaction with land generates, but the steering currents largely support a continued swift progression to the WNW. Karl is forecast to re-strengthen over the Gulf of Mexico, and I see no reason to believe it won't. The forecast track takes Karl on a continued W to WNW heading into Northern Mexico over the weekend. Karl may become a hurricane before making its final landfall over the weekend. This is reflected in the current forecast. Karl is no threat to the United States, and will have no direct impacts. Moisture levels may increase somewhat over our area to increase rain chances just a bit for Friday into the weekend if Karl remains a weaker entity, but a stronger Karl would mean lesser rain chances around these parts. This is the extent of what impacts Karl will have on our area. There is absolutely no way Karl can impact the Northern Gulf Coast because high pressure in firmly in control over the Gulf Coastal Plain. High pressure acts as a buffer with respect to tropical systems. Karl will move inland Friday night into Saturday morning, and decay over the mountains of Mexico. It will become a life-threatening flash flood and mudslide producer at that time.
Tropical Storm Karl Advisory
1a.m. CDT Wednesday, September 15, 2010
...Karl, the Season's 11th Named Storm Intensifies a Bit More, & is Nearing the Yucatan Peninsula...
Latitude: 18.6 N
Longitude: 86.0 W
This is 150 miles E of Chetumal, Mexico.
Maximum Sustained Winds: 45 mph w/ higher gusts. Some further strengthening is expected before Karl reaches the Yucatan Peninsula later today. Weakening will ensue after that while Karl is over land, and then re-strengthening is expected over the Gulf of Mexico beginning Thursday. Tropical storm force winds extend outward to 35 miles from the center.
Movement: WNW or 290 degrees @ 15 mph. This general motion is forecast to continue for the next few days, with a gradual decrease in forward speed as Karl moves inland over the Yucatan. On this track, the system will move over the Yucatan later today, and emerge into the Southern Gulf of Mexico on Thursday.
Minimum Central Pressure: 29.50" or 999 mb.
Watches/Warnings...A Tropical Storm Warning is in effect for the East Coast of the Yucatan Peninsula from Chetumal at the Belize/Mexico border Northward to Cabo Catoche. A Tropical Storm Watch is in effect for the coast of Belize from Belize City to the Belize/Mexico border.
Wind...Tropical storm conditions will reach the Yucatan Peninsula later this morning.
Storm surge...Storm surge flooding will occur along and to the North of where the center makes landfall. The surge will be accompanied by large and damaging waves.
Elsewhere, no tropical cyclone formation is expected through Thursday.
...Marine Forecast...
Today...East winds 5 to 10 knots becoming southeast 10 to 15 knots in the afternoon. Seas 1 to 2 feet.
Tonight...East winds 10 to 15 knots. Seas 2 to 3 feet.
Thursday...East winds 10 to 15 knots. Seas 3 feet. A slight chance of showers and thunderstorms.
Thursday Night...East winds 10 to 15 knots. Seas 2 to 3 feet. A slight chance of showers and thunderstorms.
Friday...East winds 10 to 15 knots. Seas 2 to 3 feet building to 3 to 4 feet in the afternoon. A slight chance of showers and thunderstorms.
Have a great Wednesday & God Bless!
-DM-
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