Area forecast discussion
National Weather Service Marquette Michigan
757 am EDT Thursday may 23 2013
Update...
issued at 729 am EDT Thursday may 23 2013
Increasing clouds...particularly in the north...with the middle to low
clouds pushing in from south central Canada and across Lake
Superior. Even the small scale/local forecast models did not pick this
up well. There looks to be some breaks in the clouds as they move
across Lake Superior...but with strong northerly flow...expect them
to stick around through much of the morning hours over the northern
reaches of the County Warning Area.
&&
Short term...(today and tonight)
issued at 455 am EDT Thursday may 23 2013
As has been the case over the past couple of mornings...we have been
keeping a close eye on a few of the rivers over the west half of Upper
Michigan...that have been rising with our steady rains. The rain continues
to shift to our southeast...as of 830z southeast of a line from Pembine and Powers
to Grand Marais. Expect all but a little lingering dz by 12z over
the far east.
The main threats over the next 24 hours will be the gusty north-north-northwest
winds today and frost/freeze overnight. The increased pressure
gradient between the exiting surface low stretching from the lower Great
Lakes to S Quebec...and strong high sinking in from central Canada
will keep gusts in the 20-25kt range through much of the day. Expect
the stronger winds to diminish west to east through the day today.
If we did not have as much rain as we have had since may 19th...and
high temperatures were going to be a bit warmer...today may have been
considered a fire day. High temperatures should be in the 40s near Lake
Superior...while in the 50s well inland. Precipitable water values in all the cold
dry air will fall to around 20-25 percent of normal /or around
0.2in/ over west and central Upper Michigan by 18z today...with relative humidity values
bottoming out 25-30 percent over the interior west half.
As for tonight...the lowest temperatures to be over the typical cool
locations of the interior west half of Upper Michigan. Under a strong
inversion...light winds should help surface temperatures fall into the low 20s.
Along the central and Eastern Lake shores temperatures in the middle 30s will
be more common. Precipitable water values will rebound slightly...up to around 40
percent of normal by 12z /or around 0.3in/. It/S the perfect time to
remember that normal lows are generally in the low 40s for this time
of year...and frost/freeze conditions are common. We will officially
begin our frost/freeze headline program on may 27th. Until then the
potential will continue to be highlighted in the forecast and in the
severe weather potential statement.
Long term...(friday through wednesday)
issued at 455 am EDT Thursday may 23 2013
Upper air pattern will consist of a 500 mb trough in the eastern U.S.
With a closed 500 mb low and trough in the Pacific northwest and a ridge
between the two troughs over the central U.S. 12z Friday. Trough in the
eastern U.S. Moves slowly the the eastern Seaboard 12z Sat with the
ridge building into the plains and this remains into 12z sun.
Interesting to note that the models keep trying to generate some
precipitation on Friday night into Sat over the western County Warning Area. Looks like the
right rear quadrant of a jet streak is moving across the area...but
thinking is that moisture will be hard to come by with the surface ridge
in place and dry air will win out...so continued the dry forecast
for Friday night into Sat. Think the models might be overdone with
their moisture and with the jet streak near the area...will see some
middle and high level clouds instead. Did go slightly cooler for high
and low temperatures for Friday and Saturday based on mixing 850 mb
temperatures down to the surface. At best...this gives ME lower 60s for
highs on Saturday and lowered a few degrees from going forecast
based on this and also the cold start to the morning on Friday
night. Ideal radiational cooling conditions set up for Friday night and
Sat night which would argue for lower temperatures with the light
winds. Other than that...kept forecast dry and kept some frost in
the forecast even though frost and freeze products are not done yet
with growing season not really starting until after Memorial Day.
In the extended...GFS and European model (ecmwf) all show a 500 mb trough in the
Pacific northwest and one over New England with a closed low there and a
ridge over the plains 12z sun. The ridge moves east into the
Mississippi River valley 12z Monday. Pattern does not change much for
12z Tuesday into 12z Wednesday except that a surface warm front heads slowly north
towards the area. This period will also start a slow warming trend
with temperatures below normal going to near normal towards the end
of the period as a ridge builds into the upper Great Lakes 12z Wednesday.
With the warm front approaching the area...chances for precipitation start to
increase Monday night across the west and then across the entire County Warning Area
by Tuesday night. Will go with slight chance to very low chance probability of precipitation as
the warm front approaches the area.
&&
Aviation...(for the 12z tafs through 12z Friday morning)
issued at 757 am EDT Thursday may 23 2013
Strong winds gusting 20-30kts will diminish west to east today...as
the pressure gradient weakens between the exiting surface low over the
lower Great Lakes and southern Quebec...and the strong high pressure
system sinking in from central Canada. Expect gusts of 20kts or
greater at saw during the entire daylight hours today. Otherwise
expect improving conditions.
&&
Marine...(for the 4 am Lake Superior forecast issuance)
issued at 455 am EDT Thursday may 23 2013
Winds will continue to decrease across the area as the pressure
gradient loosens as high pressure moves into the area. Drier air
will also move across the area allowing any lingering fog to
dissipate. As high pressure continues to spread across the upper
Great Lakes through the weekend...expect winds less than 20 kts on
Lake Superior. Lighter winds will continue into early next week.
&&
MQT watches/warnings/advisories...
Upper Michigan...
none.
Lake Superior...
none.
Lake Michigan...
none.
&&
$$
Update...kf
short term...kf
long term...07
aviation...kf
marine...07
