Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Duluth Minnesota
709 PM CDT Thursday Jul 24 2014

Update...
issued at 705 PM CDT Thursday Jul 24 2014

Updated for new aviation forecast discussion below.

&&

Synopsis...
issued at 410 PM CDT Thursday Jul 24 2014

Much of northern Minnesota and portions of northwestern
Wisconsin...however...there is still uncertainty as to the
specific location and timing of these showers. The rain has
already developed in southern Canada and in portions of western
North Dakota this afternoon. This activity will increase in
coverage and continue east-southeast tonight. The rain should
linger across The Arrowhead of Minnesota during the day tomorrow.
After the rain moves out tomorrow...look for a pronounced warming
trend on Saturday with many sites warming into the 80s. The heat
will be short-lived as a cold front moves through on
Sunday...thus cooling temperatures and bringing another chance for
showers and storms. Seasonable and dry weather is expected most of
next week.

Short term...(this evening through friday)
issued at 410 PM CDT Thursday Jul 24 2014

A weakening surface ridge in WI and a deepening surface trough in
the northern plains has resulted increasing southeast flow across
western Minnesota. At the same...along the eastern slope of the upper
ridging...increased 925-850mb moisture transport is fueling an
area of thunderstorms off to the southwest. Locally...much of the
Northland and northwest WI remains in a drier airmass with the >1"
precipitable waters off to the west of the forecast area. The focus tonight will
be on our chances for thunderstorms riding anticyclonically around
the upper ridge. There are a couple areas of interest with
shortwave energy riding along the longwave ridge and convection
breaking out in the region of thickness diffluence out ahead of
the advancing upper low. The 24.12z has seemingly had the best
handle on the convection off to the southwest today...but overall
consensus among 06-12z model guidance and the assortment of cam
output today has been poor and nothing seems to be handling the
current convection particularly well. Those disagreements carry
over into tonight...but the pattern would suggest decent thunder
chances across the forecast late tonight and early tomorrow
morning. The best window appears to be 09-15z. The southern
forecast area remains on the nose of the low level jet tonight and we should
see moisture advection as well during this time.

Long term...(friday night through thursday)
issued at 410 PM CDT Thursday Jul 24 2014

The upper ridge breaks down Friday night and a cold front
transverses the area during the day on Saturday. While widespread
isn't necessarily expected along the front. The passing upper low
should spread showers across the area on Sunday. Sunday
morning/afternoon will likely be breezy as the surface low deepens as it
moves southeast across the western Great Lakes in response to the upper
jet. No changes in the extended period beyond this weekend with both
the ec/GFS advertising a strong upper ridge building off the East
Coast of North America with a deepening long wave trough across
the eastern 1/3 of the Continental U.S.. this will keep our region cooler
than normal and mainly dry. Although cooler temperatures are
expected...Standard anomalies are not too impressive compared to
the deep southeast U.S. Where anomalies could drop to 2-3 blw normal. For
comparison...our region will be slightly cooler...but still nice
for late July/early August.

&&

Short term...(this evening through friday)
issued at 410 PM CDT Thursday Jul 24 2014

A weakening surface ridge in WI and a deepening surface trough in
the northern plains has resulted increasing southeast flow across
western Minnesota. At the same...along the eastern slope of the upper
ridging...increased 925-850mb moisture transport is fueling an
area of thunderstorms off to the southwest. Locally...much of the
Northland and northwest WI remains in a drier airmass with the >1"
precipitable waters off to the west of the forecast area. The focus tonight will
be on our chances for thunderstorms riding anticyclonically around
the upper ridge. There are a couple areas of interest with
shortwave energy riding along the longwave ridge and convection
breaking out in the region of thickness diffluence out ahead of
the advancing upper low. The 24.12z has seemingly had the best
handle on the convection off to the southwest today...but overall
consensus among 06-12z model guidance and the assortment of cam
output today has been poor and nothing seems to be handling the
current convection particularly well. Those disagreements carry
over into tonight...but the pattern would suggest decent thunder
chances across the forecast late tonight and early tomorrow
morning. The best window appears to be 09-15z. The southern
forecast area remains on the nose of the low level jet tonight and we should
see moisture advection as well during this time.

Long term...(friday night through thursday)
issued at 410 PM CDT Thursday Jul 24 2014

The upper ridge breaks down Friday night and a cold front
transverses the area during the day on Saturday. While widespread
isn't necessarily expected along the front. The passing upper low
should spread showers across the area on Sunday. Sunday
morning/afternoon will likely be breezy as the surface low deepens as it
moves southeast across the western Great Lakes in response to the upper
jet. No changes in the extended period beyond this weekend with both
the ec/GFS advertising a strong upper ridge building off the East
Coast of North America with a deepening long wave trough across
the eastern 1/3 of the Continental U.S.. this will keep our region cooler
than normal and mainly dry. Although cooler temperatures are
expected...Standard anomalies are not too impressive compared to
the deep southeast U.S. Where anomalies could drop to 2-3 blw normal. For
comparison...our region will be slightly cooler...but still nice
for late July/early August.

&&

Aviation...(for the 00z tafs through 00z Friday evening)
issued at 705 PM CDT Thursday Jul 24 2014

VFR conditions will persist for the most part throughout the taf
period. Some local MVFR ceilings/visibilities will accompany scattered
showers and thunderstorms. It looks like the best window of
opportunity for showers and storms would be later tonight and
again during the afternoon on Friday.

&&

Preliminary point temps/pops...
dlh 59 77 60 81 / 20 30 40 30
inl 56 78 57 80 / 20 40 50 50
brd 64 80 61 84 / 30 30 20 30
hyr 59 77 59 84 / 30 30 30 30
asx 58 77 58 82 / 20 30 40 30

&&

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

$$

Update...dap
short term...mpx
long term...mpx
aviation...dap

National Weather Service Glossary of Abbreviations