Special Weather Statement, NWS Twin Cities, MN

Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
1250 PM CDT TUE JUL 5 2016

.MESOSCALE DISCUSSION...
Issued at 1250 PM CDT Tue Jul 5 2016

The boundary layer continues to heat and moisten up across
southern Minnesota early this afternoon as mid level cloud cover
scatters. Very steep mid level lapse rates associated with the
stout EML are spreading overhead from the Dakotas with MLCAPE as
high as 3000j/kg near the surface low over east central SD. One
cluster of non-severe thunderstorms near Morris and Wheaton, MN
has recently formed on the leading edge of the richer Theta-e.
This may eventually pose a severe threat as CIN erodes during the
next hour or two, but otherwise should produce heavy rain and
frequent lighting.

Later this afternoon as the low heads into southwestern MN and CIN
is removed, potentially explosive development will take place
across west central MN in an environment characterized by MLCAPE
values of 3000-4000 J/kg and effective shear of 35-45 kt. This
will be quite favorable for supercells with very large hail
potentially tennis ball size or larger likely. The tornado threat
will be tempered a bit by weak low level shear, but locally backed
flow at the surface from other surrounding supercells could
enhance the potential. The clusters of storms should evolve into a
line by late this afternoon and race east southeastward across
east central/southeast Minnesota and west central/southwest
Wisconsin if a cold pool can become well organized. Damaging winds
would then be the main threat, as well as locally heavy rainfall
along the tail ends of the line where training is possible. The
Twin Cities and perhaps just south/west appear to be well
positioned to experience the apex of the bow and some of the
stronger wind gusts per several CAMs, including the 12Z HopWRF
and recent runs of the HRRR.

&&

.SHORT TERM...(Today and tonight)
Issued at 300 AM CDT Tue Jul 5 2016

Surface analysis this morning shows two noticeable low pressure
centers, one over the southeast corner of Manitoba province and
the other over south-central Montana, both linked by a snaking
cold front. There is a third weaker low pressure center near the
ND/SD/MN triple point with a N-S oriented warm front in the
vicinity of this low center. Aloft, flow is nearly zonal, possibly
slightly ridge-like, between more definitive trough features over
the Appalachians and the intermountain Rockies. Minor
perturbations aloft combined with increased omega in vicinity of
the warm front within a deeply moist airmass is making for
scattered showers/t-storms in central MN early this morning.
Though some of the storms have been able to grow, instability is
not yet heightened to promote anything greater than isolated
strong/severe t-storm development.

However, strong low-level southerly flow will advect dewpoints of
nearly 70 degrees into the region later today while being caught in
a modest warm sector today will allow high temps to climb to the 80-
90 degree range. This combination alone will enhance instability
this afternoon to have MLCAPES in the 2000-3000 j/kg range. What is
more noticeable in the latest model runs is stronger shear aloft and
steeper lapse rates later today into this evening, now in the 6-8
deg C from H7-H5. As the wavy front mentioned earlier shifts east,
the frontal lift will transition the storm mode from a clustered
supercellular type to a more MCS/squall line type. As such, this
would shift the main hazard from large hail/tornado to damaging
winds as this event progresses. The timing of the event looks to
start in central MN around 20z-21z then progress eastward through
the rest of the afternoon and evening, taking advantage of the
heating of the day and the approach of a mid-to-upper level jet
streak. The event then looks to continue through about 03z-04z this
evening before diminishing in strength. Have nudged pops up to 80
percent and tried to time the hourly gridded products to reflect the
progression of the strong precipitation, but this may well need
refinement as this event unfolds.

As an aside, the Storm Prediction Center has maintained an Enhanced
Risk of severe thunderstorms for the entire WFO MPX coverage area
for today. Additional information can be found throughout the day in
their Day 1 Outlook and on their website.

In addition to the severe parameters, the aforementioned surge in
moisture will push PWATs to the 1.75-2.00 range for much of the
area. Given the ease with which precipitation should be generated
today due to the multiple features at play, it would not be
difficult to have periods of heavy rain, especially for eastern MN
through western WI. The convective nature mitigates the issuance of
a flash flood watch but with flash flood guidance between 1-3 hours
in the 2-3 inch range, isolated flooding issues cannot be ruled out.
Will add mention of this to the Hazardous Weather Outlook (HWO).

Finally, a third main concern behind the severe weather and heavy
rain concerns is elevated heat index values. The combination of
temperatures climbing to near 90 for much of of central and southern
Minnesota with dewpoints into the lower 70s will push heat index
values to the 94-97 degree range. The duration of such heat index
values is not expected to be long since the peak heating of the day
will be quickly followed by incoming showers/t-storms. In addition,
these heat index values look to fall just short of meeting heat
advisory criteria (generally 100 degrees). Therefore, am opting to
hold off issuing a heat advisory and add mention to the HWO.

.LONG TERM...(Wednesday through Monday)
Issued at 300 AM CDT Tue Jul 5 2016

The longer term concerns are overall timing of next frontal
boundary with its attendant hazards and then warming trend into
next weekend.

Initially...Wednesday appears to be a transition day with weak
high pressure following the Tuesday frontal event. It should
remain dry during the day. The models in fair agreement on
overall trend of next upper trough and frontal passage Thursday
into Thursday night. Ahead of the upper trough..the GFS drives a
short wave and convection rapidly east across Sought Dakota and
into southern Minnesota by 12z Thursday. The ECMWF is slower with
this feature. We will hold off on likely pops until Thursday
afternoon over parts of the east. This will continue into the
following night as the system moves through. With forcing
generated by the trough...we can expect an area of heavy rainfall
over some portion of the cwa during this period. At the present
time...we have forecast most of the area with another 1 inch to
1.7 inches of rain from Wed night through Thu Night. Much of any
heavy rain placement will be driven by previous convective
patterns and how far south any boundary will be driven. The 12z
GEFS mean QPF and M-Climate percentile was favoring southern
Minnesota...shifting from KMSP area into western Wisconsin
Thursday evening. This has been the overall trend of the models
the last few days. The severe weather threat also is present as
the system moves through...but will be highly conditional and
driven from previous convective events. See day 3 SPC outlook for
details.

Cooler and drier conditions develop into at least the first part
of the weekend...with overall model trends indicating ridging
aloft by Sunday which should bring warmer air back into the area
along with the increasing chance of thunder arriving early next
week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1250 PM CDT Tue Jul 5 2016

One large cluster of thunderstorms just southwest of AXN appear to
be weakening as they head toward the airport, with redevelopment
to the south. This should continue to be the case during the next
few hours until the better moisture can push a bit further north.
Otherwise, expect scattered severe storms to develop across west
central MN during the mid afternoon, organize into a line and race
east southeastward across the TAF sites late this afternoon
through mid-late evening. Severe wind gusts are most likely at
MSP/RNH/EAU when the system's organization has been peaked.

KMSP...Best timing appears to be just before 00z through mid
evening for thunderstorm activity with the severe threat expected
near the front end of the activity. LIFR conditions and winds of
45+ kts are expected with the line.

/OUTLOOK FOR KMSP/
Wed night...Mainly VFR. Chc -TSRA late. Wind E 5 kts.
Thu...Mainly VFR. TSRA likely. Wind E 5-10 kts.
Fri...Mainly VFR. Chc -TSRA. Wind NW 10-15.

&&

.MPX Watches/Warnings/Advisories...
WI...None.
MN...None.
&&

MESOSCALE...BORGHOFF
SHORT TERM...JPC
LONG TERM...DWE
AVIATION...BORGHOFF

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1258 PM CDT TUE JUL 5 2016

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
061800-
DOUGLAS-TODD-MORRISON-MILLE LACS-KANABEC-STEVENS-POPE-STEARNS-
BENTON-SHERBURNE-ISANTI-CHISAGO-LAC QUI PARLE-SWIFT-CHIPPEWA-
KANDIYOHI-MEEKER-WRIGHT-HENNEPIN-ANOKA-RAMSEY-WASHINGTON-
YELLOW MEDICINE-RENVILLE-MCLEOD-SIBLEY-CARVER-SCOTT-DAKOTA-
REDWOOD-BROWN-NICOLLET-LE SUEUR-RICE-GOODHUE-WATONWAN-BLUE EARTH-
WASECA-STEELE-MARTIN-FARIBAULT-FREEBORN-POLK-BARRON-RUSK-
ST. CROIX-PIERCE-DUNN-PEPIN-EAU CLAIRE-
1258 PM CDT TUE JUL 5 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
MINNESOTA...EAST CENTRAL MINNESOTA...SOUTH CENTRAL MINNESOTA...
SOUTHEAST MINNESOTA...SOUTHWEST MINNESOTA...WEST CENTRAL
MINNESOTA...NORTHWEST WISCONSIN AND WEST CENTRAL WISCONSIN.

.DAY ONE...THIS AFTERNOON AND TONIGHT

THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON AND EVENING. HAZARDS INCLUDE LARGE HAIL AND DAMAGING
WINDS...BUT ISOLATED TORNADOES MAY ALSO DEVELOP ACROSS WESTERN
MINNESOTA. HEAVY RAINFALL AND LOCALIZED FLOODING ARE POSSIBLE.

HIGH TEMPERATURES TODAY FOR MUCH OF THE AREA WILL CLIMB INTO THE
LOWER 90S. THESE TEMPERATURES COMBINED WITH DEWPOINTS IN THE
UPPER 60S TO MID 70S WILL PUSH HEAT INDEX VALUES TO THE 95 TO 100
DEGREE RANGE. IF OUTDOORS TODAY...PRECAUTIONS SHOULD BE TAKEN TO
AVOID HEAT RELATED ILLNESSES.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

CHANCES OF THUNDERSTORMS CONTINUE FROM WEDNESDAY NIGHT THROUGH
FRIDAY MORNING. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS
ACROSS SOUTHERN MINNESOTA THURSDAY. LOCALLY HEAVY RAINFALL AND
FLASH FLOODING ARE POSSIBLE AREA WIDE THROUGH THURSDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION WILL BE NEEDED THIS AFTERNOON AND
EVENING.

BORGHOFF

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
817 AM CDT TUE JUL 5 2016

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0816 AM     HEAVY RAIN       2 E MORRIS              45.59N 95.87W
07/05/2016  M4.51 INCH       STEVENS            MN   CO-OP OBSERVER

            24 HOUR TOTAL.

&&

MKM

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1226 PM CDT TUE JUL 5 2016

MNZ047-051800-
STEVENS-
1226 PM CDT TUE JUL 5 2016

...A STRONG THUNDERSTORM WITH HEAVY RAIN WILL AFFECT STEVENS
COUNTY...

AT 1225 PM CDT...A STRONG THUNDERSTORM WAS LOCATED NEAR DONNELLY...OR
NEAR MORRIS...MOVING EAST AT 45 MPH.

HEAVY RAIN AND NICKEL SIZE HAIL IS POSSIBLE WITH THIS STORM.

LOCATIONS IMPACTED INCLUDE...
MORRIS...HANCOCK...CHOKIO...DONNELLY...LAKE HATTIE...FISH LAKE...
ALBERTA AND MORRIS AIRPORT.

THIS INCLUDES U.S. HIGHWAY 59 BETWEEN MILE MARKERS 159 AND 177.

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY CAUSE
LOCALIZED FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

LAT...LON 4576 9625 4576 9576 4551 9574 4544 9575
      4557 9624 4573 9626
TIME...MOT...LOC 1725Z 267DEG 40KT 4567 9594

JRB

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
155 PM CDT TUE JUL 5 2016

MNZ047-051930-
STEVENS-
155 PM CDT TUE JUL 5 2016

...A STRONG THUNDERSTORM WITH HEAVY RAIN WILL AFFECT CENTRAL STEVENS
COUNTY...

AT 154 PM CDT...A STRONG THUNDERSTORM WAS LOCATED OVER FISH
LAKE...OR 9 MILES WEST OF MORRIS...MOVING EAST AT 45 MPH.

HEAVY RAIN AND WIND GUSTS UP TO 50 MPH AND NICKEL SIZE HAIL ARE
POSSIBLE WITH THIS STORM.

LOCATIONS IMPACTED INCLUDE...
MORRIS...HANCOCK...CHOKIO...DONNELLY...FISH LAKE...ALBERTA AND MORRIS
AIRPORT.

THIS INCLUDES U.S. HIGHWAY 59 BETWEEN MILE MARKERS 159 AND 172.

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY CAUSE
LOCALIZED FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

LAT...LON 4576 9625 4576 9621 4563 9576 4551 9574
      4544 9576 4558 9624
TIME...MOT...LOC 1854Z 286DEG 38KT 4563 9608

JRB