Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/21/19

Area Forecast Discussion

National Weather Service Marquette MI

 634 PM EDT Sat Apr 20 2019

.SHORT TERM...(This evening through Sunday)
Issued at 411 PM EDT SAT APR 20 2019

WV imagery and RAP analysis indicated a mid/upper level ridge from
the southern Plains to the northern Great Lakes between lows over
Hudson Bay and OH/KY/WV. A shortwave trough sliding through northern
Ontario was dragging a cold front into northern MN. Otherwise,
southerly winds and sunshine ahead of the front pushed temps into
the mid 60s over most of Upper Michigan. However, lake breezes have
dropped temps into the 40s and 50s along the Great Lakes.

Tonight, as the front continues to sag into Upper Michigan,
increasing 800-600 mb fgen behind the front is expected to support a
band of rain from ne MN into wrn Lake Superior and portions of west
Upper Michigan, mainly after 06z. Enough spread remains with the
short term high res models and SREF so that only chance POPs are
included with the highest chances into the northwest.

Sunday, the front will slowly drop through the rest of Upper
Michigan with the stronger fgen and higher pcpn chances lingering
over the northwest half. Otherwise northeast winds and clouds will
spread into the area. A strong north-south temp gradient near or
behind the front will result in highs in the mid 40s north and mid
60s south.

.LONG TERM...(Sunday night through Saturday)
Issued at 359 PM EDT SAT APR 20 2019

The main focus of the long-term is the potential for a prolonged
moderate, to at times heavy, rain event Sunday night into Tuesday
morning. It is not out of the question that some locations could see
upwards of 1-2`` of rain. Given the antecedent conditions (saturated
soils, snowmelt already causing elevated flows/levels on rivers, and
areas across the Keweenaw Peninsula and far eastern Upper Michigan
that still have 8+ inches of liquid water within the snowpack), the
potential for this persistent, heavier rain causes concern for
additional and worsening of ongoing flooding issues. Did issue an
ESF to highlight the potential hydro issues coming up, but this will
need to be closely monitored into early next week.

Sunday night through Monday, a weak cold front is progged to stall
across the region as shortwave energy begins to lift northeast
towards the Upper Mississippi Valley and warm air advection returns
northward. Along this stalled front, a strengthening baroclinic zone
aloft, PWATs pushing 1+ inch, and warm cloud depths approaching 8-
10k feet will aid in additional lift/support for a focused area of
heavier rain. Initially, the main area of concern looks to be across
western Upper Michigan Sunday night into Monday morning. As the
above mentioned baroclinic zone slowly pushes eastward Monday into
Tuesday and mid-level impulses lift across the area, rain will become
widespread and gradually shift eastward across central and eastern
Upper Michigan. Another concern is the potential for training
precipitation into Tuesday morning due to parallel mid-level flow
across the baroclinic zone. This may lead to enhanced rainfall
totals in spots. Models aren`t in good agreement with the shortwave
trough progged to dig south across the Upper Mississippi Valley on
Tuesday, finally giving the pesky baroclinic zone the push it needs
to vacate the area. Therefore, confidence isn`t high in regards to
when precipitation will come to an end during the day on Tuesday.
However, by Tuesday night the above mentioned shortwave will
continue to dig south across the region, ushering in post-frontal
high pressure and a brief period of dry conditions for Tuesday night
and Wednesday.

Towards the end of the week, a quick moving shortwave will push a
weak cold front across the Upper Great Lakes, bringing another
chance for rain on Thursday.
&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 634 PM EDT SAT APR 20 2019

VFR conditions will continue through tonight. Some showers will
begin moving in at IWD and CMX toward daybreak on Sunday, but MVFR
conditions at IWD and CMX should hold off until mid morning Sunday
and at SAW by late Sun afternoon.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 411 PM EDT SAT APR 20 2019

Northeast winds of 20 to 25 knots are expected on the western end of
Lake Superior Sunday. Otherwise, a quiet stretch of weather will
continue as winds remain below at or below 20 knots into much of next
week.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...JLB
LONG TERM...Ritzman
AVIATION...07
MARINE...JLB