Scientific Forecaster Discussion
fxus63 kmpx 251732
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
1232 PM CDT Tue Jun 25 2019
Short term...(today through wednesday)
issued at 435 am CDT Tue Jun 25 2019
Short term concerns remain convective threat over the far northeast
County Warning Area this afternoon and threat of convection developing later tonight
Isolated showers finally dissipating across the Minnesota County Warning Area. Patchy mid
clouds remains. Should see plenty of sunshine with some cumulus
developing. Some hires models develop some widely scattered
convection over the northeast County Warning Area later afternoon and ending in the
early evening. The short wave over northeast North Dakota is forecast
to move east and drop over northeast Minnesota this afternoon. MUCAPES are
forecast to around 500 j/kg over the far northeast County Warning Area in the
afternoon. Will mention small chance pop over the far northeast for
the afternoon/early evening. Elsewhere, some cumulus expected with
breezy conditions developing into the afternoon, we are expecting
temperatures to warm through the upper 70s to lower 80s.
Later tonight, we see warm air advection pattern developing to the southwest. This
could develop some scattered thunder into the southwest later
tonight. Some hires solutions develop some elevated convection to
the southwest and over South Dakota later tonight associated with a
possible short wave. The href solution moves this possible complex
east into western Minnesota Wednesday morning and dieing to the southeast
by late morning. The 06z NAM backed off on overall instability into
Minnesota but still has the short wave moving in. Will have to carry a
small pop into Wednesday morning over the west for the possibility
href/hrrr/arw solution. By late afternoon or early evening the
surface warm front will be working into southwest Minnesota and will be the
focus for convective development possibly before 00z Thursday to the
southwest as airmass becomes very unstable. Wednesday high
temperatures are expected to warm to the 80 to 85 degree range.
Long term...(wednesday night through monday)
issued at 435 am CDT Tue Jun 25 2019
The first potential heat wave of the Summer and convective trends
through Monday continue to be the focus for the long term.
The warm front will lift north Wednesday night with potential
convection firing as soon as late Wednesday afternoon. The chance
will grow Wednesday evening as a low level jet develops over the Central
Plains to eastern Nebraska and western Iowa. Elevated mixed layer
will also advance north with lapse rates exceeding 8 c/km across
southern Minnesota Wednesday night. In addition, rich low level moisture
will reach the County Warning Area during this period, allowing for only a
weakly capped atmosphere overnight and MUCAPE exceeding 3000
j/kg. Negative factors for thunderstorm development include
rising mid level heights and a forcing mechanism aside from the
low level jet. If a remnant mesoscale convective vortex or other disturbance can also interact with
this environment, there will be a good risk of severe thunderstorms
south of I-94.
By Thursday, models are in decent agreement in showing a
disturbance riding the crest of the ridge across the upper Midwest
during the late morning and afternoon. If convection is void
Wednesday night, the risk of thunderstorm development will be
quite a bit higher Thursday afternoon with this wave moving
across. Temperatures may also be cooler than forecast Thursday,
should we have a severe mesoscale convective system move through during peak heating.
The ridge builds in aggressively Friday, Saturday, and Sunday
with a 595 dm height expected across the Central Plains Saturday.
At this point, it appears the probability is low for convection
during this period with disturbances likely remaining well to the
north and east. However, the risk is not zero with mesoscale
features acting as the main driver for convection in these
circumstances. Continued to keep forecast highs and lows close to
the nbm, but did raise highs a couple degrees in some places
Saturday. 925 mb temps of +26 to +28c on most of the guidance
suggests highs in the mid 90s in most places, and possibly upper
90s over west central Minnesota. In addition, ample moisture at the 850
mb level would keep surface dew points from mixing too low,
despite the lack of evapotranspiration expected from delayed
agriculture growth. Dew points should rise into the lower 70s,
which would make for heat indices in the upper 90s to lower 100s
Saturday. Lows Friday and Saturday nights should remain in the mid
70s most locations. Excessive heat warnings or heat advisories
are appearing likely, especially given the lackluster heat we have
had all season.
The heat should persist into Sunday and possibly into early next
week. There are differences amongst the guidance with how far
south a cold front sags during this period. Adding to the
temperature uncertainty is convective potential with said front.
Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1232 PM CDT Tue Jun 25 2019
VFR conditions are expected through the period, with a cu field
building into the afternoon. A few isolated showers and
thunderstorms are possible across central Minnesota and west-
central Wisconsin but should stay north of stc and rnh, gusty
west winds will continue until sunset, with gusts of 25-30 kts
likely. Winds will diminish to around 5 kts overnight, and back
to southerly through tomorrow morning. A complex of thunderstorms
moving east out of the Dakotas overnight is expected to diminish
before it reaches area terminals, so no precipitation is expected
through tomorrow morning.
Kmsp...west winds around 15 kts with gusts to 25 kts will continue
/Outlook for kmsp/
Thu...VFR. Chc MVFR/tsra. Winds south-southeast 5-10 kts.
Fri...VFR. Winds southeast 5-10 kts.
Sat...VFR. Winds S 5-10g15 kts.