Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 041747
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1247 PM CDT FRI SEP 4 2015

.UPDATE...
ISSUED AT 1247 PM CDT FRI SEP 4 2015

UPDATED FOR 18Z AVIATION DISCUSSION BELOW

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 343 AM CDT FRI SEP 4 2015

AT 343 AM...THE AXIS OF AN UPPER LEVEL RIDGE WAS OVER MINNESOTA
AND NW ONTARIO..INCLUDING RIGHT THROUGH THE CENTRAL/WESTERN
FORECAST AREA. SURFACE HIGH PRESSURE WAS CENTERED OVER QUEBEC. AN
AREA OF LOW PRESSURE WAS OVER WESTERN SOUTH DAKOTA. MUCH OF THE
NORTHLAND HAD CLEAR SKIES AND VERY LIGHT EASTERLY WINDS...BUT HIGH
CLOUDS WERE SPREADING INTO THE WESTERN FORECAST AREA. THERE WAS
ALSO A BAND OF SCT/BKN LOW CLOUD COVER STRETCHING FROM CENTRAL
MINNESOTA...THROUGH THE SOUTHERN FORECAST AREA...AND INTO CENTRAL
WISCONSIN. THIS WAS ASSOCIATED WITH A WEAK BAND OF LOW/MID LEVEL
FRONTOGENESIS. SOME LOCATIONS IN THE SE FORECAST AREA WERE
REPORTING MIST/FOG.

EARLY THIS MORNING...PATCHY FOG IS POSSIBLE ACROSS MUCH OF THE
FORECAST AREA. THIS SHOULD DISSIPATE WITHIN A COUPLE HOURS AFTER
SUNSET. SOME MODELS ARE SUGGESTING THAT LOW/MID LEVEL
FRONTOGENETICAL BAND COULD RESULT IN ISOLATED/SCATTERED WEAK
SHOWERS OVER THE SOUTHERN FORECAST AREA. DECIDED TO KEEP THE
FORECAST DRY SINCE MOST MODELS WERE DRY AND THESE SHOWERS MAY ONLY
AMOUNT TO SPRINKLES...BUT WILL KEEP AN EYE ON DEVELOPMENT FOR REST
OF THE SHIFT.

THIS AFTERNOON...THE UPPER LEVEL RIDGE WILL SHIFT TO THE EASTERN
FORECAST AREA. THE HIGH CLOUDS OVER THE NORTHLAND THIS MORNING
SHOULD MOSTLY DISSIPATE...LEADING TO MOSTLY SUNNY SKIES FOR THE
NORTHLAND. THERE WILL BE INCREASING EAST/NE WINDS OVER WESTERN
LAKE SUPERIOR IN RESPONSE TO THE LOW PRESSURE IN THE
DAKOTAS. THE WINDS WILL KEEP AREAS DOWNWIND AND CLOSE TO LAKE
SUPERIOR MUCH COOLER THAN INLAND AREAS...ESPECIALLY FOR PARK POINT
AND THE CITY OF SUPERIOR. MUCH OF THE SHORELINE WILL BE LIMITED TO
THE UPPER 60S AND LOW 70S...BUT AREAS WELL INLAND WILL REACH THE
LOW TO MIDDLE 80S.

THIS EVENING AND TONIGHT...A SHORTWAVE TROUGH WILL LIFT THROUGH
THE PLAINS THIS AFTERNOON AND EVENING...AND THEN THE NORTHLAND
TONIGHT. THIS APPROACHING WAVE WILL PROBABLY RESULT IN SHOWERS AND
THUNDERSTORMS ACROSS THE NORTHLAND OVERNIGHT. THE HIGHEST CHANCES
OF PCPN WILL BE ACROSS THE WESTERN FORECAST AREA. THE HIGH
RESOLUTION MODELS ARE GENERALLY INDICATING STORMS DEVELOPING IN
THE NORTHERN PLAINS THIS AFTERNOON AND EVENING...AND THEN
SPREADING INTO THE WESTERN FORECAST AREA THIS EVENING. THERE IS A
RISK OF STRONG TO SEVERE STORMS OVER THE WESTERN FORECAST AREA.
THE SREF/NAM12/GFS INDICATE MOST UNSTABLE CAPE COULD EXCEED 2000
J/KG...AND DEEP LAYER WIND SHEAR MIGHT APPROACH 30 KNOTS.
THEREFORE...THERE COULD BE SOME ORGANIZED STORM CELLS CAPABLE OF
PRODUCING LARGE HAIL AND DAMAGING WINDS. THE HIGH FREEZING
LEVELS...THOUGH...AT ABOUT 14 TO 15 KFT AGL...WILL ALSO MAKE IT
SOMEWHAT DIFFICULT FOR STORMS TO PRODUCE THE LARGE HAIL.
PRECIPITABLE WATER VALUES WILL APPROACH 1.8 INCHES...SO THE DEEP
MOISTURE WILL ALLOW EFFICIENT RAIN PROCESS. STORMS COULD RESULT IN
HEAVY RAINS.

SATURDAY...THERE COULD BE LINGERING SHOWERS AND STORMS SATURDAY
MORNING AS THE SHORTWAVE TROUGH FINISHES MOVING THROUGH THE
FORECAST AREA. THEN THE UPPER LEVEL RIDGE WILL REBUILD INTO THE
NORTHLAND. THIS RIDGE SHOULD HELP SUPPRESS CONVECTION DURING THE
MIDDLE OF THE DAY. THE WARM SOUTHERLY FLOW WILL ALLOW TEMPERATURES
TO CLIMB BACK INTO THE LOW TO MIDDLE 80S. IT WILL ALSO BE VERY
HUMID. DEW POINT TEMPERATURES WILL LIKELY REACH THE UPPER 60S AND
LOW 70S. IT WILL BE COOLER NEAR THE SHORELINE BECAUSE OF THE
ONSHORE LAKE FLOW. THERE WILL BE INCREASING CHANCES OF SHOWERS AND
STORMS OVER THE SOUTHERN AND WESTERN FORECAST AREA DURING THE
AFTERNOON. THE MODELS LACK AGREEMENT WHEN ANOTHER SHORTWAVE
TROUGH IN THE PLAINS MOVES INTO THE FORECAST AREA...WHICH WOULD
BRING HEIGHT FALLS AND THE MEANS TO DEVELOP SHOWERS AND STORMS.
THE GFS AND GEM KEEP THE NORTHLAND PRIMARILY DRY DURING THE
AFTERNOON SINCE THESE MODELS DO NOT BRING THE SHORTWAVE INTO THE
REGION INTO THE EVENING...BUT THE NAM12/SREF/ECMWF ARE
SIGNIFICANTLY FASTER.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 343 AM CDT FRI SEP 4 2015

SATURDAY NIGHT...SHORTWAVE TROF DIGGING INTO NORTHERN PLAINS WILL
RESULT IN HEIGHT FALLS ACROSS THE NORTHLAND. SURFACE LOW IS
EXPECTED TO BE LOCATED OVER THE DAKOTAS AT THE START OF MY PERIOD
WITH SHOWERS AND THUNDERSTORMS LIKELY ONGOING OVER WESTERN AND
SOUTHERN CWA. EXPECT STORMS TO ADVANCE NORTHEAST ACROSS AREA
THROUGH SUNDAY MORNING. DETERMINISTIC NAM/GFS AND SREF PWATS OVER
NORTHERN MINNESOTA SATURDAY NIGHT EXPECTED TO BE AROUND 2 INCHES
WHICH IS GREATER THAN THE MAXIMUM OBSERVED PWAT AT INL FOR THAT
DAY. HEAVY RAINFALL WILL BE POSSIBLE WITH ANY OF THE STORMS WHICH
DEVELOP. THERE IS ALSO A THREAT FOR LARGE HAIL AND DAMAGING WIND
GUSTS.

UPPER TROF WILL MOVE INTO THE CANADIAN PRAIRIES ON SUNDAY...WITH
THE INITIAL SURFACE LOW MOVING TOWARD HUDSON BAY AND A SECONDARY
LOW DEVELOPING IN EASTERN MONTANA. A STRONG COLD FRONT WILL BE
SITUATED OVER THE EASTERN DAKOTAS SUNDAY MORNING...AND WILL MOVE
EASTWARD ACROSS MINNESOTA BY MONDAY MORNING. ANOTHER ROUND OF
STRONG STORMS AND HEAVY RAINFALL IS EXPECTED FOR SUNDAY AFTERNOON
THROUGH MONDAY MORNING. HEAVY RAINFALL...LARGE HAIL...AND GUSTY
WINDS ARE POSSIBLE WITH THIS SECOND ROUND OF STORMS. IN ADDITION
TO THE THUNDERSTORM THREAT...SUNDAY IS EXPECTED TO BE VERY WARM
AND MUGGY. TEMPERATURES WILL CLIMB INTO THE LOW 70S TO LOW
80S...WITH DEWPOINTS IN THE UPPER 60S AND LOW 70S. THIS
COMBINATION WILL YIELD HEAT INDEX VALUES IN THE LOW TO UPPER 80S.

COOLER AND DRIER AIRMASS MOVES INTO THE REGION ON MONDAY AND
TUESDAY BRINGING AN END TO THE THUNDERSTORM THREAT. UPPER TROF
WILL TRANSITION TO A CUTOFF LOW OVER MANITOBA DURING THE PERIOD
AND WILL SLOWLY MIGRATE EASTWARD. QUASI-ZONAL FLOW WILL DEVELOP
OVER THE UPPER MIDWEST LIMITING PRECIPITATION CHANCES MONDAY AND
EARLY TUESDAY. A SHORTWAVE TROF IS EXPECTED TO ROTATE AROUND THE
WESTERN EDGE OF THE UPPER LOW ON TUESDAY AFTERNOON THROUGH
WEDNESDAY...WHICH MAY BRING SCATTERED SHOWERS TO NORTHERN
MINNESOTA. THUNDERSTORMS ARE NOT EXPECTED AT THIS TIME...DUE TO
WEAK INSTABILITY. HIGH PRESSURE AND QUIETER CONDITIONS ARE
EXPECTED FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1247 PM CDT FRI SEP 4 2015

PESKY MORNING FOG HAS FINALLY ERODED ACROSS THE IRON RANGE AND
BRAINERD LAKES REGION... WITH ALL TAF SITES CURRENTLY REPORTING
VFR CONDITIONS. VRF WILL PREVAIL FOR MUCH OF THE DAY... BUT
AN APPROACHING STORM SYSTEM WILL COMPLICATE THE FORECAST AFTER
00Z... BRINGING CHANCES OF SHOWERS AND STORMS TO THE NORTHLAND.
EXPECTING CONDITIONS TO FALL TO MVFR/IFR AFTER 06Z DUE TO EITHER
LOW CIGS/VIS WHERE IT IS RAINING... OR LOW VIS WHERE IT IS NOT
RAINING BUT PATCHY FOG HAS FORMED. FCST MAY NEED TO BE FINE TUNED
LATER TO ACCOUNT FOR POSSIBLE LOWER VIS/CIGS. A GENERAL
IMPROVEMENT BACK TO LOW END VFR IS EXPECTED AFTER 16Z SATURDAY...
BUT THIS WILL LIKELY BE SHORT LIVED AS ANOTHER DISTURBANCE IS
EXPECTED TO IMPACT THE NORTHLAND SATURDAY EVENING.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  74  62  81  68 /  10  50  30  70
INL  82  67  82  67 /  20  70  30  80
BRD  84  70  86  70 /  30  40  40  80
HYR  82  67  86  70 /  10  30  30  50
ASX  74  63  84  69 /  10  30  20  40

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...BEACH HAZARDS STATEMENT UNTIL 8 PM CDT THIS EVENING FOR WIZ001.

MN...BEACH HAZARDS STATEMENT UNTIL 8 PM CDT THIS EVENING FOR MNZ037.

LS...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LSZ144-145.

&&

$$

UPDATE...MCLOVIN
SHORT TERM...GROCHOCINSKI
LONG TERM...HUYCK
AVIATION...MCLOVIN


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