Updraft: August 28, 2012 Archive

Update: Slow moving Isaac pounds New Orleans

Posted at 10:19 PM on August 28, 2012 by Paul Huttner (1 Comments)
Filed under: Heat, Hurricanes

10:30 pm Update:

10 foot storm surge at Shell Beach Louisiana just SE of New Orleans

85 mph wind gust in Gulf of Mexico SE of Grand Isle, LA

PRELIMINARY LOCAL STORM REPORT NATIONAL WEATHER SERVICE NEW ORLEANS LA 801 PM CDT TUE AUG 28 2012

0712 PM HURRICANE 1 SSE GRAND ISLE CMAN 29.26N 89.96W
08/28/2012 JEFFERSON LA C-MAN STATION

MEASURED N 58KT/67MPH GUST 74KT/85MPH.

230,000 without power late Tuesday night and growing fast

Source: Entergy New Orleans

Radar loop shows Isaac's eye near Grand Isle.
Source: WxUndergorund

Hurricane Isaac made a brief landfall over the mouth of the Mississippi Tuesday night, then the center wobbled over open water.

HURRICANE ISAAC DISCUSSION NUMBER 32 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012 1000 PM CDT TUE AUG 28 2012

ISAAC PASSED OVER THE MISSISSIPPI RIVER DELTA IN EXTREME SOUTHEAST LOUISIANA AROUND 2345 UTC. SINCE THAT TIME...THE CENTER HAS WOBBLED WESTWARD AND HAS MOVED BACK OVER WATER. A NORTHWESTWARD MOTION HAS RECENTLY RESUMED AND A SECOND LANDFALL SHOULD OCCUR LATER TONIGHT NEAR GRAND ISLE.

Most of Isaac's circulation is still over the warm open waters of the Gulf of Mexico, and that means Isaac may maintain hurricane strength for a longer period overnight.

Spiraling bands of hurricane strength will continue to spin into New Orleans overnight and into Wednesday morning.

Isaac will slowly come ashore overnight, and the slow moving storm will linger and batter New Orleans with bands of heavy rain, wind and storm surge.

The story of Isaac will be told on Wednesday as we find out how well the levees and pumps withstand sustained surge and 10"+ rainfall barrage.

PH

****

"Hurricane" Isaac - Isaac finally reaches hurricane strength

80 mph - Category 1 storm

Gaining strength - Isaac better organized than ever before

6 to 12 foot storm surge battering Louisiana Coast

Landfall tonight near the mouth of the Mississippi River

Live streaming coverage of Isaac from WWL TV in New Orleans

Free desktop streaming application by Ustream

Isaac crawls ashore:

The "forecast" part of Isaac is almost over now. The "news" part of the storm is in full swing, and will take over coverage in the coming days.

Here's the Tuesday 4 PM NHC update on Isaac in the hours before he comes ashore. Isaac is likely at or near peak strength.

400 PM CDT TUE AUG 28 2012

...ISAAC GETTING BETTER ORGANIZED AS IT NEARS SOUTHEASTERN
LOUISIANA...FLOODING FROM STORM SURGE AND RAINFALL EXPECTED...

SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...28.7N 89.2W
ABOUT 30 MI...45 KM SSW OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 105 MI...170 KM SSE OF NEW ORLEANS LOUISIANA
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...975 MB...28.79 INCHES

Isaac has become more circular today, and may be slightly stronger just before landfall. He is also a large, slow moving storm. That means the impacts will last for a good 24+ hours in and near New Orleans.

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 80 MPH...130 KM/H... WITH HIGHER GUSTS. ISAAC IS A CATEGORY ONE HURRICANE ON THE SAFFIR- SIMPSON HURRICANE WIND SCALE. SOME SLIGHT STRENGTHENING IS POSSIBLE BEFORE ISAAC MAKES LANDFALL. GRADUAL WEAKENING IS EXPECTED AFTER LANDFALL OCCURS.

HURRICANE-FORCE WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM...MAINLY TO THE NORTHEAST AND EAST OF THE CENTER. TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 185 MILES...295 KM. TROPICAL STORM CONDITIONS ARE OCCURRING ALONG THE COASTAL AREAS OF SOUTHEASTERN LOUISIANA...MISSISSIPPI...AND ALABAMA. NOAA BUOY 42040...LOCATED EAST OF THE MOUTH OF THE MISSISSIPPI RIVER...RECENTLY MEASURED SUSTAINED WINDS OF 63 MPH...100 KM/H...AND A GUST TO 83 MPH... 135 KM/H.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 975 MB...28.79 INCHES.

What are the likely effects from Isaac?

The biggest threats with Isaac are the levee battering storm surge and the potential for multi inch rainfall totals that can overwhelm city pumps and resources.

HAZARDS AFFECTING LAND
----------------------
STORM SURGE...THE COMBINATION OF A STORM SURGE AND THE TIDE WILL
CAUSE NORMALLY DRY AREAS NEAR THE COAST TO BE FLOODED BY RISING
WATERS. THE WATER COULD REACH THE FOLLOWING DEPTHS ABOVE GROUND IF
THE PEAK SURGE OCCURS AT THE TIME OF HIGH TIDE...

* MISSISSIPPI AND SOUTHEASTERN LOUISIANA...6 TO 12 FT
* ALABAMA...4 TO 8 FT
* SOUTH-CENTRAL LOUISIANA...3 TO 6 FT
* FLORIDA PANHANDLE...3 TO 6 FT
* APALACHEE BAY...2 TO 4 FT
* REMAINDER OF FLORIDA WEST COAST...1 TO 3 FT

THE DEEPEST WATER WILL OCCUR ALONG THE IMMEDIATE COAST IN AREAS OF ONSHORE WINDS. SURGE-RELATED FLOODING DEPENDS ON THE RELATIVE TIMING OF THE SURGE AND THE TIDAL CYCLE...AND CAN VARY GREATLY OVER SHORT DISTANCES. FOR INFORMATION SPECIFIC TO YOUR AREA...PLEASE SEE PRODUCTS ISSUED BY YOUR LOCAL WEATHER SERVICE OFFICE. NEAR THE COAST...THE SURGE WILL BE ACCOMPANIED BY LARGE AND DANGEROUS WAVES.

WIND...TROPICAL STORM CONDITIONS WILL CONTINUE TO SPREAD ACROSS THE WARNING AREA THIS EVENING...AND HURRICANE CONDITIONS SHOULD SPREAD ONSHORE ACROSS SOUTHEASTERN LOUISIANA DURING THE NEXT FEW HOURS.

WINDS AFFECTING THE UPPER FLOORS OF HIGH-RISE BUILDINGS WILL BE SIGNIFICANTLY STRONGER THAN THOSE NEAR GROUND LEVEL. AT ABOUT THE 30TH STORY...WINDS WOULD LIKELY BE ONE SAFFIR-SIMPSON CATEGORY STRONGER THAN AT THE SURFACE.

RAINFALL...ISAAC IS EXPECTED TO PRODUCE TOTAL RAINFALL AMOUNTS OF 7 TO 14 INCHES...WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 20 INCHES...OVER MUCH OF LOUISIANA...SOUTHERN MISSISSIPPI...SOUTHERN ALABAMA...AND THE EXTREME WESTERN FLORIDA PANHANDLE. THESE RAINS COULD RESULT IN SIGNIFICANT LOWLAND FLOODING.

TORNADOES...TORNADOES ARE POSSIBLE ALONG THE NORTHERN GULF COAST THROUGH TONIGHT.

Eye on Isaac detected by doppler:

Isaac is close enough to NWS radar to see the eyewall as it spins toward shore. The eyewall is the most intense part of the hurricane, and will pack the highest wind gusts as the squalls move through.

Source: WxUnderground

The worst of the storm from a wind perspective will be tonight as the still developing eyewall spins into New Orleans. With several hours of 80+ mph winds, I expect significant tree, window and roof damage from Isaac. Widespread power outages are likely by tonight in and near New Orleans.

Minnesota Forecast: "Heat Storm" ahead

It looks like we're in for one more blast from the hot summer of 2012.

A blast furnace like dome of high pressure is moving into Minnesota this week.

Temperatures soared well over 100 degrees in Nebraska & South Dakota Tuesday.

Source: Sioux Falls NWS

I'm forecasting 96 for the metro Wednesday, and near 100 Thursday. The record both days is 96 degrees.

Get ready for one more shot of intense summer heat in Minnesota.

PH

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