000
FXUS63 KDLH 170119
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
819 PM CDT THU MAY 16 2013

.UPDATE...DELAYED THE ONSET OF PCPN AS VERY DRY AIR WILL BE TOUGH
TO OVERCOME. OTHER MINOR TWEAKS WERE MADE.

&&

.PREV DISCUSSION... /ISSUED 636 PM CDT THU MAY 16 2013/

AVIATION...00Z TAFS.
VFR AT THE OUTSET WITH CI SHIELD OVERSPREADING THE TERMINALS WITH
SOME MID CLOUDS. APPEARS THE RAIN WILL WORK INTO THE BRD AREA BY
12Z WITH MVFR CIGS...THEN DLH/HYR AROUND 15Z AND HIB NEAR 17Z.
HAVE KEPT INL WITH VFR WHICH SHOULD BE ON THE NORTHERN PERIPHERY
OF THE RAIN.

PREV DISCUSSION... /ISSUED 323 PM CDT THU MAY 16 2013/

SHORT TERM.../NOW - FRIDAY/

THE FOCUS IS ON THE POTENTIAL FOR SHOWERS AND STORMS WITH AN MCS.
THE MCS IS CURRENTLY NEAR SE SOUTH DAKOTA AND NE NEBRASKA WITH A
WARM FRONT STRETCHING FROM NEBRASKA TO SOUTHERN WISCONSIN. THE
MODELS INDICATE...WITH VARYING DIFFERENCES...THAT THE MCS WILL
MOVE AND LIFT NORTH AND EASTWARD TONIGHT INTO FRIDAY AS THE WARM
FRONT LIFTS NORTH AND THE MID/UPPER LEVEL RIDGE OVER THE CENTRAL
US AMPLIFIES AND LIFTS NORTHWARD. THE NAM/SREF/WRF-NMM TAKE THE
MCS MUCH FARTHER NORTH THAN THE GFS/GEM/ECMWF...WHICH GENERALLY
BRING THE MCS ACROSS OR NEAR THE SOUTHERN FORECAST AREA. I LEANED
ON THE GFS/GEM/ECMWF...BUT INCORPORATED THE SREF AND NAM IN MY
BLEND...WHICH RESULTED IN INCREASING AND SPREADING POPS NORTHWARD.
I AM NOT CONVINCED ENOUGH OF THUNDER TO INCLUDE IT IN THE FORECAST
FOR MOST OF THE FORECAST AREA...BUT THERE MAY BE A LITTLE THUNDER
ACROSS THE SOUTHERN FORECAST AREA CLOSER TO THE HEART OF THE MCS.

THROUGH TONIGHT...CLOUD COVER WILL INCREASE AS MID/HIGH CLOUDS IN
THE DAKOTAS AND WESTERN MINNESOTA SPREAD EASTWARD INTO THE
NORTHLAND. THE MCS IN THE PLAINS WILL LIKELY MOVE AND LIFT NORTH
AND EAST TONIGHT AS THE WARM FRONT STRETCHING ACROSS IOWA AND
SOUTHERN WISCONSIN LIFTS NORTHWARD. RAIN SHOWERS FROM THE MCS AND
SHOWERS ACROSS CENTRAL/EASTERN NORTH DAKOTA COULD BEGIN TO MOVE
INTO THE SOUTHWESTERN AND WESTERN FORECAST AREA AROUND OR AFTER
MIDNIGHT. CHANCES WILL INCREASE AND SPREAD NORTH AND EASTWARD
THROUGH THE REST OF THE NIGHT AS THE MCS APPROACHES THE NORTHLAND.
OVERNIGHT LOWS SHOULD BE IN THE 40S TO NEAR 50 DEGREES WITH THE
COLDEST TEMPERATURES NEAR LAKE SUPERIOR.

FRIDAY...IT SHOULD AT LEAST BE A CLOUDY AND AND COOLER DAY ACROSS
THE NORTHLAND DUE TO THE APPROACHING MCS. I LOWERED TEMPERATURES
BASED ON THE LATEST MODEL GUIDANCE AND THE LIKELIHOOD OF THE CLOUD
COVER INHIBITING WARMING. THE BIG QUESTION IS HOW FAR NORTH THE
MCS WILL LIFT. THE GLOBAL MODELS GENERALLY TAKE THE MCS NEAR OR
ACROSS THE SOUTHERN FORECAST...WHILE THE HIGHER RESOLUTION MODELS
GENERALLY MUCH FARTHER NORTH. I AM MORE APT TO BELIEVE IN THE
SOUTHERN SOLUTION DUE TO THE EXPECTED COOL EASTERLY WINDS THAT
WILL BE COMING OFF LAKE SUPERIOR. HOWEVER...I DID INCREASE AND
SPREAD POPS NORTHWARD. SOME PARTS OF THE SOUTHERN FORECAST
AREA...IF THIS ENDS UP BEING THE TRACK OF THE MCS...COULD GET SOME
SIGNIFICANT RAIN...MAYBE UP TO A HALF INCH. I INCLUDED A SLIGHT
CHANCE OF THUNDER ACROSS THE FAR SOUTHERN FORECAST AREA...BUT I AM
NOT CONFIDENT ENOUGH OF THUNDER FOR THE CENTRAL AND NORTHERN
FORECAST AREA.

LONG TERM.../FRIDAY NIGHT - WEDNESDAY/

THE EXTENDED PERIOD WILL BE CHARACTERIZED BY AN ACTIVE WEATHER
PATTERN...COMPARED TO THE PREVIOUS WEEK. AN UPPER LEVEL RIDGE
ACROSS THE CENTRAL US LATE FRI AND SAT WILL HELP ADVECT IN A WARM
AND UNSTABLE AIR MASS ACROSS THE UPPER MIDWEST. AN ASSOCIATED WARM
FRONT WILL LIFT SLOWLY NWD THROUGH CENTRAL/NRN MN LATE FRI NIGHT
AND THROUGH THE DAY SATURDAY...AND FOCUS SHOWERS AND STORMS OVER
MUCH OF THE NORTHLAND. THERE IS SOME UNCERTAINTY REGARDING HOW FAR
NORTH THE FRONT WILL LIFT. THERE IS A GENERAL CONSENSUS THAT THE
FRONT WILL STALL OUT SOMEWHERE ACROSS FAR NRN MN...AROUND OR JUST
NORTH OF THE IRON RANGE TO THE INTL BORDER. THE POSITION OF THE
FRONT WILL NOT ONLY DETERMINE PRECIPITATION AMOUNTS AND
LOCATION...BUT ALSO BE A SIGNIFICANT FACTOR IN DETERMINING
TEMPERATURES SAT AND SUN. THERE COULD BE ENOUGH CLEARING OR DRYING
OUT SOUTH OF THE FRONT DUE TO A STRONG CAP DURING THE MORNING
HOURS TO ALLOW TEMPS TO JUMP HIGHER THAN FORECAST...AND ALSO BUILD
UP ADDITIONAL INSTABILITY TO PRODUCE STRONGER T-STORMS. NEED TO
MONITOR HOW MUCH CLEARING TAKES PLACE IN THE WARM SECTOR THIS
WEEKEND.

THE MAIN LOW PRESSURE SYSTEM IS EXPECTED TO FOLLOW THE PRESSURE
TROUGH/WARM FRONT TO THE NE THROUGH MN AND EVENTUALLY SLOW DOWN
AND BECOME QUASI-STATIONARY LATE THIS WEEKEND AND INTO EARLY NEXT
WEEK AROUND CENTRAL/SRN MN. THIS PATTERN WILL ALLOW A HEAVY AMT OF
MOISTURE TO CONTINUALLY BE PUMPED INTO THE REGION AND RESULT IN A
EXTENDED PERIOD OF RAIN SHOWERS AND T-STORMS. THE INSTABILITY WILL
LINGER INTO MONDAY...ALONG WITH CHANCES FOR STORMS. HOWEVER BY
TUESDAY...MOST OF THE STRONGER INSTABILITY MOVES TO SE WITH THE
COLD CORE LOW AND LEAVES MUCH OF THE NORTHLAND WITH SCT RAIN
SHOWERS. WITH THE RAIN CONTINUING THROUGH WEDNESDAY...THERE IS THE
POTENTIAL FOR A SIGNIFICANT AMT OF RAINFALL...WHICH WOULD
EVENTUALLY LEAD TO POSSIBLE HYDRO CONCERNS.

TEMPERATURES WILL START OFF WARM INLAND AND COOL NEAR THE LAKE
EARLY IN THE EXTENDED PERIOD...WITH HIGHS IN THE 70S...AND UPPER
50S/60S RESPECTIVELY. BUT QUICKLY COOL OFF LATE IN THE PERIOD WITH
HIGHS GENERALLY IN THE 50S AND 60S EARLY/MID NEXT WEEK.

&&

.POINT TEMPS/POPS...
DLH  46  54  42  62 /  20  50  60  60
INL  46  67  47  61 /  20  20  50  60
BRD  48  62  51  76 /  50  60  60  70
HYR  47  58  48  73 /  20  70  60  50
ASX  41  56  45  67 /  10  60  60  50

&&

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

$$

SHORT TERM...GSF