Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Duluth Minnesota
312 am CDT Sat Jul 4 2015

Short term...(today through sunday)
issued at 312 am CDT Sat Jul 4 2015

A ridge of high pressure covered the forecast area at 07z. A few
clouds were drifting over much of the area from northwest to southeast due to the
northwest flow aloft. Areas of fog or smoke were reducing visibilities over the
entire area with the light wind. Expect the visibility restrictions in fog
or smoke to persist until 12z when some improvement is expected as
mixing erodes the fog. Left the mention of patchy smoke over the
western half of the area until 18z. After 18z...anticipating a bit
more mixing to occur and with the flow aloft switching to the
south-southwest...the smoke should begin to disperse. Latest short term model
guidance indicates there will be no precipitation through the afternoon and
have removed the probability of precipitation along the southern edge of the area.

A short wave trough is prognosticated to move into Minnesota this evening. Forcing
is primarily over southern Minnesota and with a lack of deep moisture...not
expecting any rain prior to 06z. Kept the forecast rain free through
09z Sunday with good shot of warm air advection underway. Deep moisture is still
west of the forecast area as well. After 09z...have some probability of precipitation over
the northwest portion of the area as another piece of short wave energy
arrives. A bit more uvm available...a divergence maxima also arrives
at this time and moisture is increasing in this area warranting the
probability of precipitation.

On Sunday morning...the short wave trough moves east of the area...the
upper divergence maximum lifts north into Canada and some of the
moisture dries up. However...the best remaining moisture is found
over the western third of the region along with a bit of uvm for
some probability of precipitation. By Sunday afternoon...moisture increases over the western
half of the region while a surface trough bisects the region from west to
east basically north of U.S. Highway 2 in NE Minnesota. An 850 mb low level jet
intersects the trough as some upper divergence arrives with an h25 jet
moving through south central Canada. Have the highest probability of precipitation nearest
this Junction in the northwest corner of the forecast area...trending
downward the further away from this scenario. The rest of the region
will be rain free.

Long term...(sunday night through friday)
issued at 312 am CDT Sat Jul 4 2015

A passing strong surface cold front and associated deepening upper
trough pushing into the upper Midwest Sunday night through Monday
will produce widespread rain showers and scattered thunderstorms
during this time with the main threat being heavy rain. A large
supply of deep layer moisture will be lifted northward across the
Midwest/western Great Lakes area late Sunday ahead of the front and be
deposited across the region through the day Monday. Precipitable water values will
increase into the 1.5 to 2 inch range...which is greater than 2 Standard
dev above normal. Widespread 1-1.5 inch rainfall amts are
likely...with locally higher amts possible above 2 inches. The rain
will fall in a relatively short period of time...so localized
flooding could be of concern. The system will be fairly progressive
and move out of the area late Monday with rising heights aloft and a
surface high building in behind the system. High pressure will dominate
the area into the middle of the week with the next threat for
showers and storms arriving late Wed/Thursday. At this time all
indications point to low chances for precipitation through Friday.
Could be a better chance of showers and storms this weekend.

Temperatures will continue to top out in the upper 70s and 80s
through the week with a slight warming trend over the latter half of
the period. Overnight lows will drop into the 50s and 60s.

&&

Aviation...(for the 06z tafs through 06z Saturday night)
issued at 1229 am CDT Sat Jul 4 2015

Showers and thunderstorms have moved out of the Northland and weak
high pressure will nose into the region tonight. Reduced visibilities in
fog or smoke will occur tonight...and improve Saturday morning. VFR
conditions are then expected Saturday into Saturday evening. Expect
winds to veer to southerly on Saturday...but be off of Lake Superior
close to the lake.

&&

Preliminary point temps/pops...
dlh 76 59 81 62 / 0 0 10 90
inl 83 65 79 58 / 10 30 80 50
brd 84 65 83 61 / 10 10 20 90
hyr 82 63 82 67 / 10 10 10 80
asx 74 59 82 63 / 0 0 10 70

&&

Dlh watches/warnings/advisories...
WI...none.
Minnesota...none.
Ls...none.

&&

$$

Short term...gsf
long term...tentinger
aviation...melde

National Weather Service Glossary of Abbreviations