Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 201950
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
350 PM EDT Thu Apr 20 2017

.DISCUSSION...

The ongoing convective cluster over Lower Michigan is expected to be
followed by one more round of storms along and ahead of the cold
front as it moves through the region during late afternoon and early
evening. Severe thunderstorm watch 151 is in effect until 8 PM.

Ongoing activity continues to have some potential for organization
along and south of the I-96 corridor which is about the position of
the surface warm front at press time. So far, this activity has been
marginally severe as 0-1km MLCAPE remained less than 1000 J/kg.
Similar concerns exist for the last phase of the event as the system
attempts to recover some instability between the ongoing convection
and the cold front over SW Lower Michigan. Discrete storms observed
over Indiana at press time are expected to develop northward into
Lower Michigan with a chance of gradually evolving into linear mode
thanks to increasing 0-6km effect shear. The improved wind profile
and larger scale vertical motion field will be produced by the upper
level wave moving into the region while the surface low moves into
northern Lower Michigan. This leaves a narrow window of opportunity
open for severe weather in our area through the watch expiration
and before the front exits into Ohio/Ontario.

Wraparound moisture associated with the low pressure system
will remain over the northern Great Lakes during Friday. This will
be followed by high pressure that will keep Southeast Michigan dry
while producing chilly nights this weekend and for the start of next
week. Low temperatures in the mid to upper 30s will be common each
night while typically colder locations making a run at freezing.
Daytime temperatures are projected to be in the upper 50s to around
60 degrees through Monday before readings warm back into the 60s by
middle of next week. The next chances for any precipitation is
expected by Tuesday as a shortwave skirts along the northern Great
Lakes region.

&&

.MARINE...

Surface low over central Lake Michigan will track across northern
Lane Huron tonight.  Strong easterly flow will weaken somewhat
tonight as the winds veer to the west by morning. Winds will
increase during the day Friday to about 15 to 20 knots while
veering to the northwest as high pressure approaches.  Winds and
waves may be high enough to warrant small craft advisories for the
nearshores of southern Lake Huron Friday.  Winds will weaken
over the weekend as high pressure crosses the area.

&&

.PREV DISCUSSION...
Issued at 1252 PM EDT Thu Apr 20 2017

AVIATION...

Low pressure over south central Lake Michigan will track northeast
across north central lower Michigan this afternoon. Surface warm
front currently along the southern Michigan border will struggle to
lift very far north this afternoon as cool marine layer from
northeasterly flow off the lakes produces resistance. Low stratus
ceiling less then 1kft will occur along and north of the front while
mixing in the warm sector behind the front will produce broken cu
above 3k ft. Expecting the warm front to make it through the southern
tafs sites around or shortly after taf issuance but may not make it
to PTK. Winds north of front will remain light northeasterly, winds
behind front somewhat gusty sw. Elevated showers and few
thunderstorms will occur north of the front effecting the northern
sites while more surface based showers and storms will effect the
southern sites. Some storm across the south may be severe with one
inch hail, wind gusts to 60 mph and slight chance for a tornado. All
of this activity will end from west to east in the 21-00z time frame
as a surface cold front swings . through. After west northwest flow
and low level moisture wrapping around departing low will produce
mainly mvfr ceilings through the rest of the taf period.

For DTW...Surface warm just to south will slowly lift to the north
around or shortly after taf issuance time.  Light northeasterly flow
ahead of the front is producing low stratus layer from marine layer
moisture.  South of the front diurnal mixing producing broken
ceilings aob 4kft.  Showers and thunderstorms will be on the
increase this afternoon ahead of an approaching cold front.  Some
storms may be severe with potential for wind gusts to 60mph, one
inch hail and possibly a tornado.  All activity should clear the
airport by around 00z. After, west northwest flow and low level wrap
around moisture from departing low will produce stratus below 3k ft.

//DTW THRESHOLD PROBABILITIES...

* High in ceilings below 5000 ft through taf period.

* High for thunderstorms this afternoon.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...NONE.

Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ442-443.

     Small Craft Advisory until 10 AM EDT Friday for LHZ421-441.

Lake St Clair...NONE.

Michigan waters of Lake Erie...NONE.

&&

$$

DISCUSSION...BT/BT
MARINE.......DRC
AVIATION.....DRC


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