Tropical Storm Cristobal Advisory Number 24
NWS National Hurricane Center Miami FL AL032020
1000 AM CDT Sun Jun 07 2020
...CRISTOBAL MOVING CLOSER TO SOUTHEASTERN LOUISIANA...
...HEAVY RAINFALL AND STORM SURGE EXPECTED FROM SOUTHEASTERN
LOUISIANA EASTWARD TO THE FLORIDA PANHANDLE...
SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...28.7N 90.0W
ABOUT 90 MI...145 KM S OF NEW ORLEANS LOUISIANA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...N OR 355 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...994 MB...29.36 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
None.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for...
* Mouth of the Mississippi River to Ocean Springs Mississippi
* Lake Borgne
A Storm Surge Watch is in effect for...
* East of Morgan City Louisiana to the mouth of the Mississippi
River
A Tropical Storm Warning is in effect for...
* Intracoastal City Louisiana to the Okaloosa/Walton County
Florida line
* Lake Pontchartrain and Lake Maurepas
A Storm Surge Warning means there is a danger of life-threatening
inundation, from rising water moving inland from the coastline,
during the next 36 hours in the indicated locations. For a depiction
of areas at risk, please see the National Weather Service Storm
Surge Watch/Warning Graphic, available at hurricanes.gov. This is a
life-threatening situation. Persons located within these areas
should take all necessary actions to protect life and property from
rising water and the potential for other dangerous conditions.
Promptly follow evacuation and other instructions from local
officials.
A Storm Surge Watch means there is a possibility of life-
threatening inundation, from rising water moving inland from the
coastline, in the indicated locations during the next 48 hours.
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within the next 24 hours.
For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.
DISCUSSION AND OUTLOOK
----------------------
At 1000 AM CDT (1500 UTC), the center of Tropical Storm Cristobal
was located near latitude 28.7 North, longitude 90.0 West. Cristobal
is moving toward the north near 12 mph (19 km/h), and this general
motion is expected to continue today, followed by a gradual turn
toward the north-northwest late today or tonight. On the forecast
track, the center of Cristobal will approach the northern Gulf of
Mexico coast this afternoon, then move inland across Louisiana late
today through Monday morning, and northward across Arkansas and
Missouri Monday afternoon into Tuesday.
Data from an Air Force Reserve reconnaissance aircraft and NOAA
Doppler weather radars indicate that maximum sustained winds remain
near 50 mph (85 km/h) with higher gusts. Little change in strength
is forecast before landfall. Gradual weakening will begin once
Cristobal moves inland.
Tropical-storm-force winds extend outward up to 205 miles (335 km),
mainly to the east of the center. A Weatherflow site at Bayou
Bienvenue, Louisiana, recently measured a sustained wind of 37 mph
(60 km/h) and a gust to 47 mph (76 km/h).
The estimated minimum central pressure is 994 mb (29.36 inches).
HAZARDS AFFECTING LAND
----------------------
Key messages for Cristobal can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT3, WMO header WTNT43 KNHC, and
on the web at http://www.hurricanes.gov/text/MIATCDAT3.shtml
STORM SURGE: The combination of a dangerous storm surge and the
tide will cause normally dry areas near the coast to be flooded by
rising waters moving inland from the shoreline. The water could
reach the following heights above ground somewhere in the indicated
areas if the peak surge occurs at the time of high tide...
Mouth of the Mississippi River to Ocean Springs MS including Lake
Borgne...3-5 ft
Morgan City LA to Mouth of the Mississippi River...2-4 ft
Ocean Springs MS to Marco Island FL including Mobile Bay, Pensacola
Bay, and Tampa Bay...1-3 ft
The deepest water will occur along the immediate coast in areas of
onshore winds and will likely extend along the coast well to the
east of the center. 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 National Weather Service forecast
office.
WIND: Tropical storm conditions are expected within the Tropical
Storm Warning area along the northern Gulf coast through tonight.
RAINFALL: Cristobal is expected to produce total rainfall
accumulations of 4 to 8 inches across portions of the central Gulf
Coast into the Lower Mississippi Valley, with isolated amounts to
12 inches. Rainfall totals of 2 to 4 inches with local amounts to
6 inches are expected across portions of the eastern Gulf Coast,
along with the Mid to Upper Mississippi Valley and Northern Plains
near and in advance of Cristobal. This rainfall will likely lead
to flash flooding and widespread flooding on smaller streams across
portions of the central Gulf Coast into the Lower Mississippi
Valley. New and renewed significant river flooding is possible
along the central Gulf Coast and into the Mississippi Valley.
TORNADOES: A few tornadoes are possible today and tonight across
eastern Louisiana, southern Mississippi, southern Alabama, and
northern Florida.
SURF: Swells generated by Cristobal will affect portions of the
northern and eastern Gulf coast during the next couple of days.
These swells are likely to cause life-threatening surf and rip
current conditions. Please consult products from your local
weather office.
NEXT ADVISORY
-------------
Next intermediate advisory at 100 PM CDT.
Next complete advisory at 400 PM CDT.
$$
Forecaster Stewart
Tropical Storm Cristobal Discussion Number 24
NWS National Hurricane Center Miami FL AL032020
1000 AM CDT Sun Jun 07 2020
Cristobal's inner-core remains disorganized as multiple low-level
circulations are seen rotating around the mean center used in the
advisory. A large swirl just west of the alleged center has been
dropping southward, and this could become a new center of
circulation later today. Since the previous advisory, Cristobal's
overall appearance in satellite imagery has started to look more
like a tropical cyclone with several small curved convective bands
developing, especially in the eastern semicircle, along with some
anticyclonic cirrus outflow noted. NOAA Doppler radar have
indicated average velocities of 55-58 kt between 5000-8000 ft over
the Chandeleur Sound, which equates to 45-48 kt surface winds in
the northeastern quadrant. Also, an earlier Air Force Reserve
reconnaissance mission sampled a long fetch of 55-59 kt at 925 mb in
the southeastern quadrant, which equates to 41-44 kt surface winds.
Therefore, the initial intensity is being held at 45 kt for this
advisory, which is consistent with satellite intensity estimates of
45 kt from both TAFB and UW-CIMSS ADT.
The initial motion is an uncertain 355/10 kt due to the uncertainty
in the center position. Due to the broad inner-core wind field,
there may be some erratic motion for the next 6 hours or so.
Otherwise, the models remain in very good agreement in Cristobal
turning north-northwestward later today. That motion is expected to
continue until the 36-h period as the cyclone rounds the western
periphery of a deep-layer ridged parked over the southeastern U.S.
and Tennessee Valley area. By 48 hours and beyond, the ridge is
forecast to slide eastward, allowing Cristobal to turn toward the
north on day 2, and then move northeastward on days 3 and 4. A
merger with an extratropical cyclone over the Great Lakes area is
expected by day 5. The new NHC forecast track is similar to the
previous advisory track, and lies close to the tightly packed
consensus models.
The continued broad structure of Cristobal and significant dry air
entrainment should prevent any significant intensification before
landfall, and the current intensity forecast holds the intensity
constant at 45 kt through 12 h. Although the center is expected to
be inland at that time, the long southerly wind fetch on the east
side could keep winds to 45 kt over the Chandeleur Sound, near the
coast of Mississippi and Alabama, and possibly over the inland
lakes of southeastern Louisiana. Gradual weakening is forecast after
landfall, with Cristobal weakening below tropical-storm strength
by the 24-h time period. The new intensity forecast is similar to
the previous advisory, and continues to show some slight
re-intensification after the cyclone becomes extratropical at
72-96 hours, which is in agreement with the global model guidance.
Cristobal remains a broad and asymmetric storm. Therefore, one
should not focus on the exact forecast track, since the associated
winds, storm surge, and rainfall extend well away the center.
Key Messages:
1. There is a danger of life-threatening storm surge outside of the
Hurricane and Storm Damage Risk Reduction System from the Mouth of
the Mississippi River to Ocean Springs, Mississippi, and a Storm
Surge Warning is in effect for those areas. Life-threatening storm
surge remains possible in other portions of southern and
southeastern Louisiana where a Storm Surge Watch is in effect.
Residents in these locations should follow advice given by local
emergency officials.
2. Tropical storm force winds should spread along the northern Gulf
coast from central Louisiana to the western Florida Panhandle,
including metropolitan New Orleans today, and a Tropical Storm
Warning is in effect for this area. These winds will arrive well
in advance of and extend well east of Cristobal’s center.
3. Heavy rainfall will continue across north Florida this morning,
spreading from east to west across the eastern and central Gulf
Coast from the Florida Panhandle into Louisiana today. The Central
Gulf Coast region will be most prone to issues after the passage of
the center of Cristobal from Sunday night into Monday. This heavy
rain will move up the Lower and Mid Mississippi Valley Monday into
Tuesday, then across the Upper Mississippi Valley and Northern
Plains Tuesday and Tuesday night. Flash flooding, and new and
renewed significant river flooding is possible, especially where
heavier rainfall occurs over portions of the Gulf Coast through the
Mississippi Valley.
FORECAST POSITIONS AND MAX WINDS
INIT 07/1500Z 28.7N 90.0W 45 KT 50 MPH
12H 08/0000Z 30.2N 90.5W 45 KT 50 MPH...INLAND
24H 08/1200Z 32.6N 91.6W 30 KT 35 MPH...INLAND
36H 09/0000Z 35.2N 92.2W 25 KT 30 MPH...INLAND
48H 09/1200Z 38.9N 91.6W 25 KT 30 MPH...INLAND
60H 10/0000Z 43.5N 89.6W 25 KT 30 MPH...INLAND
72H 10/1200Z 47.8N 87.1W 30 KT 35 MPH...POST-TROP/EXTRATROP
96H 11/1200Z 52.6N 83.1W 30 KT 35 MPH...POST-TROP/EXTRATROP
120H 12/1200Z...DISSIPATED
$$
Forecaster Stewart