Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 020535
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1235 AM CDT SUN AUG 2 2015

.UPDATE...
ISSUED AT 1235 AM CDT SUN AUG 2 2015

UPDATED FOR 06Z TAFS.

.UPDATE...
ISSUED AT 854 PM CDT SAT AUG 1 2015

ATTEMPTS AT SURFACE-BASED CONVECTIVE INITIATION APPEAR TO HAVE
FAILED WITHIN THE WARM FRONTAL ZONE FROM NE SD INTO WRN MN THIS
EVENING AFTER A COUPLE OF BRIEF STORMS TRIED TO SUSTAIN OVER NE
SD. WHILE 00Z SOUNDINGS REVEAL SIGNIFICANT POTENTIAL INSTABILITY..
THE LACK OF A FOCUSED LIFTING MECHANISM APPEARS TO BE THE PRIMARY
CULPRIT AS WEAK SHORT-WAVE RIDGING AND SUBSIDENCE APPEARS TO BE
OVERSPREADING THIS AREA AT THE MOMENT. A SOUTHWESTERLY LOW LEVEL
JET CONTINUES TO SLOWLY STRENGTHEN FROM NE NEBRASKA INTO THE
FRONTAL ZONE IN CENTRAL MINNESOTA..AND SPC MESOANALYSIS DATA ALSO
SUGGESTS MODEST SFC-850 FGEN IN THE WCENT MN AREA..SO WE WILL
STILL NEED TO MONITOR THE FRONTAL ZONE FOR CONVECTIVE DEVELOPMENT
FOR THE NEXT FEW HOURS. HOWEVER..IT APPEARS AS THOUGH THE ALREADY
LOW CHANCES FOR SUSTAINED INITIATION IN THIS AREA CONTINUE TO
DECREASE.

MEANWHILE..FOCUS APPEARS TO BE SHIFTING TO AREAS FARTHER NORTHWEST
IN ADVANCE OF MORE SIGNIFICANT S/W TROF THAT IS DRIVING THE MAIN
SURFACE COLD FRONT THAT LIES FROM JUST SOUTH OF WINNIPEG TO JUST
NORTH OF MINOT ND AS OF 830 PM. SATELLITE/RADAR HAVE REVEALED
CONVECTION HAS CONTINUED TO BUBBLE OVER SW MANITOBA FOR THE PAST
SEVERAL HOURS..WITH A FAIRLY RAPID INCREASE IN COVERAGE/INTENSITY
NOTED BETWEEN BOTTINEAU ND AND BRANDON MB DURING THE PAST HOUR. IF
THIS ACTIVITY CAN HOLD TOGETHER AND ORGANIZE..IT APPEARS TO BE IN
A FAIRLY IDEAL POSITION TO RIDE SEWD ALONG/JUST NORTH OF THE
INSTABILITY GRADIENT NEAR WHERE THE NOSE OF THE LLJ WILL INTERSECT
THE INSTABILITY GRADIENT ACROSS THE RED RIVER VALLEY AND INTO
CENTRAL/NRN MN AFTER MIDNIGHT. WHILE THIS ACTIVITY WILL BE ROOTED
IN AN ELEVATED LAYER..THERE APPEARS TO BE AT LEAST SOME RISK FOR
STRONG WINDS AND MARGINALLY LARGE HAIL WITH THE STRONGEST UPDRAFTS
GIVEN THE SUSTAINED FORCING FROM THE APPROACHING WAVE AND
PERSISTENCE OF STRONG DEEP LAYER SHEAR AND 1000-2000 ELEVATED CAPE
THROUGH THE NIGHT.

FORECAST HAS ALREADY BEEN UPDATED TO REFLECT THE ABOVE REASONING
WITH THE MAIN CHANGES BEING TO LOWER POPS SOUTH THIS EVE AND
RAISING THEM SUBSTANTIALLY AFTER MIDNIGHT THRU MID MORNING SUNDAY
ACROSS THE CENTRAL AND NORTH. WE MAY NEED TO UPDATE AGAIN ONCE THE
CONVECTIVE EVOLUTION UPSTREAM BECOMES CLEARER.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1235 AM CDT SUN AUG 2 2015

VFR CONDITIONS GENERALLY EXPECTED THROUGH THE TAF PERIOD WITH A
CHANCE FOR A BRIEF PERIOD OF MVFR VISIBILITY AND CEILING HEIGHTS
DUE TO ISOLATED STORMS OVERNIGHT OVER THE NEXT 6-12 HOURS.

OVERNIGHT/EARLY SUNDAY MORNING...A THUNDERSTORM COMPLEX IN
SOUTHERN MANITOBA IS MOVING SOUTHEAST INTO FAR NORTHWEST MINNESOTA
AND IS EXPECTED TO CONTINUE TO MOVE ACROSS NORTHEAST MINNESOTA
EARLY THIS MORNING. ELEVATED INSTABILITY SHOULD SUSTAIN THESE
STORMS...THE STRONGEST OF WHICH HAVE PRODUCED HAIL TO AT LEAST
QUARTER SIZE AND GUSTS IN EXCESS OF 60 MPH. COVERAGE OF STORMS
WILL BE FAIRLY ISOLATED THROUGH THE MORNING SO CHANCE OF IMPACT AT
ANY INDIVIDUAL SITE IS NOT VERY HIGH...EXCEPT FOR INL WHERE STORMS
ARE LIKELY TO IMPACT WITHIN THE NEXT FEW HOURS. USED TEMPO GROUPS
TO TIME THIS AREA OF STORMS AS IT PROGRESSES INTO THE MORNING
GIVEN EXPECTED COVERAGE. CEILINGS SHOULD REMAIN VFR...THOUGH HEAVY
RAINFALL COULD RESULT IN AN MVFR/IFR STRATUS DECK FORMING THIS
DOES NOT APPEAR LIKELY. VISIBILITY MAY BRIEFLY FALL TO MVFR IN THE
STRONGEST STORMS...BUT DURATION OF THIS OBSCURATION WOULD BE BRIEF
IF IT DOES OCCUR.

FOR THE DAY...GUSTY NORTHWEST WINDS EXPECTED AS SKIES PARTIALLY
CLEAR OUT OVER NORTHEAST MINNESOTA WHILE ISOLATED SHOWERS/STORMS
MAY PERSIST INTO NORTHWEST WISCONSIN. A FEW GUSTS TO THE 20-25KT
RANGE ARE EXPECTED AT MOST SITES THROUGH THE AFTERNOON...WITH
WINDS RAPIDLY DIMINISHING IN THE EVENING.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  54  69  51  70 /   0  20   0   0
INL  48  65  46  67 /   0  20   0  10
BRD  54  75  51  74 /   0   0   0   0
HYR  50  71  49  71 /   0  20   0  10
ASX  53  70  51  70 /   0  10  10  10

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
LS...NONE.
&&

$$

UPDATE...MILLER/JJM
AVIATION...JJM


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