Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46

000
FXUS63 KDTX 141646
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1146 AM EST Tue Feb 14 2017


.AVIATION...

Probabilistic wind information continues to supports gusts exceeding
15 knots with at least a moderate confidence in reaching 25 knots as
well. Given the fact that gusts have already reached the 15-20 knot
range, will maintain gusts up to 25 knots, both in WSW flow this
afternoon and also NW flow tonight in wake of passing cold front.
Stratus/strato-cumulus field associated with this system remains a
bit chaotic, but generally should see a trend to MVFR as the cold
cyclonic northwest flow regimes becomes established tonight. Would
also expect at least scattered rain/snow showers in advance of the
front this evening the dynamic nature of the parent shortwave.

For DTW...Winds will veer to WSW this afternoon and then NW late
this evening as strong cold front passes. Will maintain TEMPO group
this evening for rasn showers, but lack of moisture should keep this
activity rather scattered in nature. Wind gusts should range between
20 and 25 knots at times.

//DTW THRESHOLD PROBABILITIES...

* Moderate in ceilings below 5000 ft tonight.

* Low in crosswind thresholds being exceeded this evening.

&&

.PREV DISCUSSION...
Issued at 305 AM EST Tue Feb 14 2017

DISCUSSION...

Another day with temperatures exceeding 40 degrees, ahead of a cold
front which will track through southern Lower Michigan this evening.
00z Raob out of MSP showed a 925 mb temp of 4 C, and although the
bulk of this warm air will sink southeast into the Northern Ohio
Valley, 00z euro/RAP/Regional Gem still sporting temps of 1-3 C at
925 mb during the afternoon, and based on yesterday`s results,
favor warmer NAM/Euro mos guidance for Today, mid to upper 40s.

Latest water vapor imagery shows strong upper wave sliding through
Northwestern Ontario, which will become more elongated in southeast-
northwest fashion as it tracks through Lower Michigan late this
evening. 700 MB cold pool (around -20 C) swinging through Tonight,
with 850 mb temps a bit slow to cool, only to around -10 C by 12z
Wednesday, before falling into the -12 to -15 C range during the day
on Wednesday. Lack of moisture and short window of steeper 925-700
mb lapse rates (7-7.6 C/KM) to work with, argues for just chance
pops, highest across northern thumb region where lapse rates are
steepest. Low pops also supported by local SREF weighted
probabilistic guidance, and thus most locations will not see any
measurable snow. With surface temps climbing into the 40s during
day, precip type could even be rain showers initially into early
evening hours.

Cold cyclonic flow during Wednesday will support plenty of clouds,
but mostly flurries and just isolated snow showers with low
inversion heights around 5 kft. Will have to watch the eastern thumb
shoreline closely for possible accumulating snow shower activity
however, as low level winds approach northerly direction Wednesday
Evening. With the well mixed boundary layer during the day, should
be able to tap into 25+ knots, and thus gusts between 25-30 mph
expected. Looking at highs around 30/lower 30s based off 925 mb
temps holding around -7 C.

Large upper level low slow to exit off the New England Coast on
Thursday, and low level thermal trough over Lower Michigan looks
to persist, keeping maxes near normal in the lower 30s.

Big warm-up then commences on Friday, as pronounced upper level ridge
axis (562-566 DAM at 500 mb) arrives Saturday morning, with 850 mb
temps of 10 C. If low clouds/fog does not materialize, 60 degrees is
in play for Saturday as 925 mb temps surge to at least 9 c.

MARINE...

A low pressure system will dig southeastward to north of Georgian
Bay this evening, sending a cold front through the central Great
Lakes overnight. A bit of uncertainty exists with the forecast as
overall model data is surprisingly quite muted on the forecasted
environmental wind profile throughout the lower troposphere.
In fact, modeled winds in the lowest 10 kft agl struggle to climb
much above 30 knots. Synoptic scale dynamics appear very favorable
at least with degree of support for strong frontal circulation.
Isallobaric forcing is weakening steadily during the tonight period
while missing Lake Huron to the north and east. The interesting item
for this event in particular is multiple forecast datasets that are
forecasting a very sharp thermal trough feature that will push
directly across the northern Lake Huron Basin. Local compaction of
the pressure gradient especially with possible interaction with
coastal convergence effects could allow for overachievement over
central Lake Huron. So despite, what is very lackluster
environmental wind profile, will keep the Gale Watch going for a
smaller footprint of the open waters of the northern Lake Huron
basin.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Gale Watch from late tonight through Wednesday morning for LHZ362-
     363.

Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

AVIATION.....DG
DISCUSSION...SF
MARINE.......CB


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.