Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 240934
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
534 AM EDT Fri Mar 24 2017

.UPDATE...
Issued at 437 AM EDT Fri Mar 24 2017

Temps still hovering in the lower 30s in the tip of the mitt with
another batch of showers now spreading into the region and
dewpoints still under 30F. Apparently enough cooling to produce
light icing on area roads (particularly back roads) as reported
from incoming shift and local schools. Thus, have decided to
hoist WW.Y for parts of northern lower Michigan through 9 am.

&&

.NEAR TERM...(Today through Tonight)
Issued at 327 AM EDT Fri Mar 24 2017

...Periodic light freezing rain...

High Impact Weather Potential...light freezing rain/icing this
morning and possibly again tonight.

Pattern Synopsis/Forecast...Split flow pattern across the CONUS
this morning with the southern branch diving into a closed mid
level circulation across the SW CONUS where a strong mid level
short wave and occluding surface low pressure system is
found...and warm front arcing up through the midwest/southern
lower Michigan. Northern branch runs across the northern tier of
states and across the Great Lakes with a strengthening upper jet
core running across the far northern lakes region. Northern stream
surface low resides across Hudson Bay with a cold front swinging
through Ontario...pressing into the far northern lakes. Strong
Warm advection forcing along and north of the warm front has
produced several batches of precip (and spotty thunder) sliding
across the state overnight. Precip is mainly liquid...causing some
FZRA issues across upper Michigan. Temps are above freezing
across northern lower Michigan although dewpoints remain in the
20s and some spotty light icing has also been reported by a few
ASOS obs across the higher terrain and the tip of the mitt.

Occluded low pressure near the Kansas/Colorado border will slowly
advance through the south-central plains today and into Missouri
tonight...while associated warm front remains somewhat stationary
arcing through the midwest and across far southern lower Michigan.
Northern stream cold front sags into northern Michigan...while
strong canadian high pressure builds through Ontario and noses
into the northern lakes region by Saturday morning. Northern
Michigan remains between these two systems with increasing
confluent mid level flow/deformation setting up across the region.

Primary Forecast Concerns...Icing concerns this morning and again
tonight.

Initial batch of warm advection forcing/precip will push east of
the region early this morning. But...increasing confluent
flow/and a relatively narrow low-mid level deformation axis will
set up across Wisconsin and eastward across northern lower
Michigan...then remain in place through much of the day. One can
already see this setting up upstream per regional radar plots
along with a nice push of moisture from the upstream low
spreading northeastward into the midwest. Shaping up to for a
narrow axis of rainfall/high POPs/higher QPF pointing right
across the CWA...with guidance right now suggesting areas north of
M-72 to the straits seeing the best chances/highest QPF.
Fortunately, surface temps will be warming safely above freezing
everywhere by mid/late morning...ending the icing threat. Will
let the current advisory for freezing rain run it`s course through
15Z...although day shift may be able to trim it earlier.

Tonight: High pressure anticipated to develop across Ontario,
suppressing tighter thermal gradient/deformation axis/precip
southward with time, while colder air begins to spread into
northern Michigan. Will probably begin to see wintry mix
precip/light icing issues once again along the northern edge of
precip axis as it pushes south...which may ultimately warrant
another winter weather advisory for parts of northern lower
Michigan tonight. But...will let day crew assess those
possibilities.

&&

.SHORT TERM...(Saturday through Sunday)
Issued at 327 AM EDT Fri Mar 24 2017

...To Ice or not to Ice Part Deux...

High Impact Weather Potential...Icing potential will impact portions
of NE Lower and E Upper Saturday night and Sunday night. The best
night for the icing with significant amounts looks to be Saturday
night.

Pattern Synopsis/Forecast...The sfc low at 12z/Sat is in central
Missouri with the 500 mb low stacked up over it. This produces an
easterly flow from the James Bay high, undercutting the warm air
aloft with cool, dry air. This keep the rain south of the Straits
for the day, but as the low crosses the Mississippi River into
Illinois 06z/Sun, the moisture and the warm front moves north
bringing the precipitation north to E Upper. soundings for E Upper
show that the likelihood of FZRA is pretty high. Models suggest that
around 0.1" is possible. Of course, as has been said the last few
days, there is a cycle to this, with Sunday starting with FZRA,
changing to -RA as the temperatures warm. Sunday night, the
temperatures in E Upper again fall below freezing with the continued
dry easterly flow. Although it looks like the temperatures in N
Lower remain above freezing through the night.

Primary Forecast Concerns...The model profiles again have the region
on the razors edge of freezing temperatures at the sfc, but are have
a decent warm nose in the mid levels. This will lead to freezing
precipitation or non-freezing precipitation. Think that with the
cool, dry easterly flow in E Upper and in NE Lower that it is more
likely to be below freezing for several hours, while the west side
of the state remains above freezing.

.LONG TERM...(Monday through Thursday)
Issued at 327 AM EDT Fri Mar 24 2017

High Impact Weather Potential...None

Extended (Monday through Thursday)...With the original low from
Sunday having filled in, a secondary low forms over southern
Missouri and begins to move up the Ohio Valley. This puts the
forecast area on the back side of the low, and we again get cooling,
but looking at the model profiles, it is of the whole column, so
will expect snow over the region (probably minor accumulations at
this point) as the low moves into New England on Tuesday. High
pressure then builds into the region and stays over the Upper Great
Lakes through the day on Thursday. Thursday night, we may be getting
into a similar situation like what we have now, with a low moving
out of the C Plains and cool, dry flow out of Ontario. There is some
uncertainty with the how this evolves, but it is something to watch.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 534 AM EDT Fri Mar 24 2017

CIGS will lower to MVFR at all terminal sites...possibly IFR at
times...as axis of rainfall sets up across northern lower
Michigan. Rain...low clouds will stick around through tonight
although high pressure and some drier will nose down into the tip
of the mitt tonight...ending precip at KPLN and KAPN. Winds will
be under 10 knots through tonight but increase on Saturday.

&&

.MARINE...
Issued at 437 AM EDT Fri Mar 24 2017

Winds/waves continue to diminish this morning and have thus
trimmed remaining small craft advisory just a little early.
Winds/waves will remain below small craft advisory criteria
through tonight. They will increase again on Saturday as low
pressure tracks up into the midwest and high pressure builds down
out of Canada. Another round of small craft advisories may be
needed for Saturday into Sunday.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY until 11 AM EDT this morning for MIZ008-
     015.
     WINTER WEATHER ADVISORY until 9 AM EDT this morning for
     MIZ016>018-022>024-028>030.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...TBA
NEAR TERM...TBA
SHORT TERM...JSL
LONG TERM...JSL
AVIATION...TBA
MARINE...TBA



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