Area forecast discussion
National Weather Service Gaylord Michigan
1013 PM EDT Sat may 18 2013
Synopsis...
issued at 316 PM EDT Sat may 18 2013
High pressure will provide a little more sunshine...thus a bit
warmer temperatures for Sunday. However...a storm system developing
over The Rockies will become better organized over the
plains...before moving into the Great Lakes to start the work week.
This approaching system will generate thunderstorms and mild
temperatures...over northern Michigan through middle week.
&&
Update...
issued at 1013 PM EDT Sat may 18 2013
Newberry and the saults continue to report occasional very light
precipitation. The rain gage at the sault Michigan ASOS has thus far refused to
click off even 0.01 inch. So sprinkles may be the best
descriptor...but with a cluster of somewhat stronger returns just
west of chip/Mack...have mentioned scattered -shra up until 07z in
eastern Upper.
Middle clouds are making a southeast-Ward push back into northern
lower...and have become more widespread north of a tvc-Rogers
line. The idea of partly cloudy south and mostly cloudy north
still looks sound...with some potential for bubbly cumulus debris
downstate to be drawn northward into southern sections overnight.
Only minor tweaks to min temperatures.
Update issued at 728 PM EDT Sat may 18 2013
Very spotty sprinkles/-shra restricted to eastern Upper Michigan (mainly
Chippewa co). Twin saults both reporting off-and-on rain in the
past couple of hours. Cloud cover has diminished considerably in
northern lower Michigan...with some partial clearing as far north as western
Mackinac. Precipitation forecast seems to be in good shape...will
continue to babysit cloud trends and adjust as needed.
&&
Short term...(this evening through sunday)
issued at 316 PM EDT Sat may 18 2013
Elevated warm front/warm air advection Wing continues to lift through
the area tonight with lingering middle level fgen and adiabatic Omega
possibly producing a few sprinkles/light shower tip of the mitt into
eastern upper. Sky conditions ranging from partly cloudy south to
mostly cloudy north. A mild night with lows from the middle 40s to
lower 50s.
By far the best day of the weekend on Sunday with 850mb thermal
ridge of 13-15c building into the area. Middle level ridging will
continue to dominate our weather picture as deeper trough digs into
the northern plains. Surface dewpoints will continue to gradually creep
up as the day progresses. NAM continuing its recent bias of too wet
lower levels...with current forecast dewpoints 3-5 degf too high based
on latest observations. Quite warm on Sunday...with high temperatures
reaching the middle 70s /eastern upper/ to lower 80s /portions of
northern lower/. Weak gradient and warm temperatures lend itself to lake
breeze development during the afternoon hours and will cool temperatures
closer to the coasts to account for this. Even with slightly lower
dewpoints than the NAM forecast soundings...modified soundings with near dry
adiabatic mixed layer yield several hundred joules of skinny cape.
Inland penetrating lake breeze boundaries...increasing surface dewpoints and
some instability support isolated shower mention for interior areas
during the middle/late afternoon.
Long term...(sunday night through saturday)
issued at 316 PM EDT Sat may 18 2013
Middle and upper level pattern becoming increasingly blocky with
time...at least partially driven by strong north central Atlantic
centered high pressure ridge axis. Dual strong shortwave troughs
diving into the Pacific northwest only helping the cause...with lead
energy eventually carving out a slow moving upper low in the nations
midsection early next work week...while the next piece does the same
across the Pacific northwest. Subsequent Canadian Prairie Ridge
building between these features sets up a quasi-Omega block
signature...with strong energy prognosticated to dive down its frontside
into east central Canada only adding further complexity to an
already complex pattern. Add in a good supply of Gulf of Mexico
moisture and fgen dynamics...and the pattern has all the makings of
a wet one through at least the first half of this upcoming week.
Latest wpc 5 and 7 day quantitative precipitation forecasts
concur...with widespread 1 to 2 inch amounts across our area...with
heavier amounts to upwards of 4 inches just to our northwest. As one
can imagine given above...extended forecast concerns mainly center
on multi-period rain shower and thunderstorm threats.
One complicated forecast Sunday night into Monday...which...to be
honest...does not support a whole lot of forecast confidence.
Central Plains closed low becomes increasingly well established...
with excellent forced low/middle level convergence zone setting up
between south flow out ahead of it weak energy diving through
Ontario. Strong 800 mb convergence axis looks to slowly sag south across
Lake Superior Sunday night into Monday...with surface reflection
essentially remaining stationary across the climatologically favored
tip of the mitt/straits region. 800 mb front looks to remain very
active...focusing much of the rain off to our north through Sunday
night...perhaps into the first part of Monday (helped in part by middle
level ridging remaining overhead). Conditions become much more
interesting heading into Monday afternoon and night as energy
rotating around upper level low interacts with an increasingly
impressive overhead moisture plume as precipitable water values approach an inch
and a half. While model depicted surface dewpoints in the upper
60s/lower 70s seem aggressive...juxtaposition of decent moisture and
middle level support should be enough to kick off rounds of showers and
storms...some of which may bring locally heavy rainfall. While
severe threat not completely zero...better potential should remain
to our southwest within corridor of much more impressive deep layer
shear and better low level instability. Latest day 3 Storm Prediction Center severe
graphics does bring the slight risk right to our doorstep over
southwest Michigan. No doubt Worth keeping an eye on the next few
days as upstream convective trends will likely play havoc with exact
thermodynamic and kinematic details. Potentially another warm one
Monday...especially south of the bridge. Thermal forecasts easily
support highs back into the lower 80s...although cloud and
convective trends may prevent full warming from being realized.
Middle-week weather dependent on interaction (or lack thereof) between
approaching middle level low and stronger energy diving south out of
Canada. The former continues to supply plenty of moisture and
dynamics...while the latter attempts to drive best fgen/baroclinic
zone further south with time. Deep layer convergence and moisture
supports plenty of rain potential...with placement of the heaviest
and steadiest rainfall tied to above interaction. 00z European model (ecmwf)/Gem
offer a rather wet scenario...keeping corridor of deep layer
convergence overhead right through Thursday. GFS a touch more
aggressive driving this corridor south...although it too suggests
lingering rains into Thursday (just not as heavy). Hard to get a
feel for which is more correct...with the end result likely a middle
ground between the two. Inherited forecast keeps rains lingering
through Thursday...as will this forecast. Severe threat should only
sag south with time as low level baroclinic zone does the same. That
said...proximity of it and some evidence for it to return briefly
north later Wednesday...as main western energy approaches...
definitely raises some concern.
Start of Memorial Day weekend looking cool and dry as Canadian high
pressure builds overhead. Highs Friday and Saturday look to only
reach into 60s (upper 50s across eastern upper?)...which would be at
least a few degrees below normal. Pattern recognition supports the
potential for some rather chilly overnight readings Thursday through
Saturday. Somewhat disconcerting to see latest climatology influenced
European model (ecmwf) MOS showing colder locations dipping into the middle and upper
30s early Friday morning...and widespread lower and middle 30 degree
readings Saturday morning. Other guidance not quite as cold...but
definitely something to monitor.
&&
Aviation...(for the 00z tafs through 00z Sunday evening)
issued at 728 PM EDT Sat may 18 2013
VFR.
Light southerly flow in place in the low and middle levels...between
high pressure over eastern Canada...and low pressure in the central/
southern High Plains. This will slowly bring more low-level moisture
into the region. Initially...band of middle/high clouds will continue
to lift north out of northern lower tonight. Patchy middle clouds
will return to northern lower overnight from the south. Sunday
will be sunnier...warmer...and somewhat more humid. Developing lake
breezes will likely trigger a few rain showers in the afternoon...but
inland from all the taf sites.
Light winds tonight into Sunday morning...with onshore winds
developing early Sunday afternoon.
&&
Marine...
issued at 316 PM EDT Sat may 18 2013
Gradient will remain relatively weak over the next few days as high
pressure slowly departs to the east. As low pressure draws closer
to the area Tuesday/Wednesday...winds will increase and small
craft conditions are possible.
&&
Apx watches/warnings/advisories...
Michigan...none.
LH...none.
Lm...none.
Ls...none.
&&
$$
Update...jz
synopsis...kb
short term...jk
long term...mb
aviation...jz
marine...jk
