Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 200407
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1107 PM CDT TUE AUG 19 2014

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 254 PM CDT TUE AUG 19 2014

AFTERNOON WATER VAPOR IMAGERY SHOWS THE HEALTHY SHORTWAVE TROUGH
OVER LAKE SUPERIOR. THIS IS THE FEATURE RESPONSIBLE FOR THE STRATOCU
CLOUDS AND SPOTTY SHOWERS ACROSS MUCH OF THE AREA TODAY. THIS SHOWER
ACTIVITY WILL DIMINISH THIS EVENING WITH THE LOSS OF DAYTIME
HEATING...AND SKIES WILL GRADUALLY CLEAR FROM WEST TO EAST AS THE
AFOREMENTIONED TROUGH SHIFT FARTHER EAST. THE CONCERN THEN BECOMES
THE POTENTIAL FOR FOG DEVELOPMENT...AS THE SURFACE RIDGE SETTLES IN
AND WINDS DECOUPLE. THE HIGHEST POTENTIAL FOR DENSE FOG APPEARS TO
BE ALONG THE MN/WI BORDER TOWARD EAU CLAIRE...IN CLOSEST PROXIMITY
TO THE SURFACE RIDGE AXIS...SOUTH/WEST OF THE AREA IN NORTHERN WI
WHERE CLOUDS MAY LINGER INTO EARLY WEDNESDAY MORNING. HAVE INCLUDED
A MENTION OF 1/2SM IN THE GRIDS/FORECAST...BUT WILL NEED TO MONITOR
TRENDS CLOSELY THIS EVE TO SEE IF DENSE FOG WILL BECOME MORE THAN
JUST PATCHY IN NATURE AND NECESSITATE AN ADVISORY.

AREAS OF FOG WILL BURN OFF BY MID MORNING WEDNESDAY...AND
TEMPERATURES WILL MODERATE INTO THE UPPER 70S TO MID 80S RANGE.
CLOUDS WILL MOVE IN FROM THE WEST DURING THE AFTERNOON AS A
SHORTWAVE TROUGH TOPS THE MID LEVEL RIDGE AND APPROACHES THE AREA.
COULD SEE SOME SHOWERS AND THUNDERSTORMS SNEAK INTO WEST CENTRAL MN
DURING THE AFTERNOON HOURS AS 850-700MB TEMP/MOISTURE ADVECTION
ENSUES.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 254 PM CDT TUE AUG 19 2014

THE LONG TERM CONTINUED TO SHOW TWO MAIN ROUNDS OF CONVECTION. THE
FIRST DEVELOPING LATE WEDNESDAY INTO THURSDAY...AND AGAIN FRIDAY
NIGHT INTO SATURDAY. OVERALL THE THE PREVIOUS FORECAST WAS IN GOOD
AGREEMENT WITH THE MODELS...SO DID LITTLE IN THE WAY OF SIGNIFICANT
CHANGES.

MODELS INDICATE SHORT WAVE MOVING ACROSS THE DAKOTAS WEDNESDAY
WITH THIS DEVELOPING A WARM FRONT WHICH WILL LIFT NORTHEAST INTO
SOUTHERN MN LATE WEDNESDAY NIGHT. STRONG H85 MOISTURE ADVECTION
DEVELOPS OUT AHEAD OF THE FRONT AND SHOULD LEAD TO MS DEVELOPMENT
MAINLY AFTER 06Z THU INTO SOUTHWEST/WEST CENTRAL MN AND THEN ROLL
EAST INTO EAST CENTRAL MN BY 12Z THU. WITH PRECIPITABLE WATERS
TOPPING 2 INCHES WITH THE SHORT WAVE...WE WILL LIKELY SEE SOME
WIDESPREAD HEAVY RAINS IN EXCESS OF 1 INCH OVER MUCH OF CENTRAL INTO
EAST CENTRAL MN INTO THURSDAY MORNING. THE MAIN MCS SHOULD WORK
EAST AND WEAKEN THURSDAY MORNING...LEAVING A FAIR AMOUNT OF
CLOUDINESS...ESPECIALLY OVER THE NORTHEAST CWA. THIS WILL LIMIT
TEMPERATURES A BIT...AND DID DECREASE THEM A BIT BECAUSE OF THE
UNCERTAINTY OF CLOUD COVER. THE WARM FRONT SHOULD EITHER MOVE INTO
SOUTHEAST MN THURSDAY OR INTO THURSDAY EVENING AS THE SHORT WAVE
CLEARS THE AREA. CONTINUED TO TAPER POPS SOME INTO THURSDAY NIGHT
WITH MID LEVEL CAP BUILDING NORTHEAST OF THE SURFACE WARM FRONT.

MODELS DIVERGE SOME IN TIMING OF THE NEXT SHORT WAVE THAT LIFTS
NORTHEAST INTO THE AREA. THE GFS RETAINS THE BLOCKY RIDGE TO THE
EAST OVER THE GREAT LAKES AND RIDES THE WAVE NORTHEAST ACROSS THE
AREA FRIDAY NIGHT INTO SATURDAY. THE 12Z ECWMF IS SLOWER...LIFTING
MOST OF THE ENERGY AFFECTING OUR AREA SATURDAY INTO SUNDAY. WILL
HAVE TO MAINTAIN SOME CHANCE POPS DURING THIS PERIOD BECAUSE OF
MODEL UNCERTAINTY OF HANDLING THE WESTERN CONUS TROUGH AND
SURFACE FRONT. THE 12Z ECWMF DOES TAKE THE FRONT THROUGH THE AREA BY
SUNDAY EVENING...WITH DRIER AND COOLER CONDITIONS DEVELOPING THAT
SHOULD LINGER THROUGH NEXT TUESDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1107 PM CDT TUE AUG 19 2014

WINDS HAVE BECOME CALM OVER ALL OF MN EXCEPT THE FAR WESTERN PART.
STILL SOME VERY LIGHT NNE WIND IN WEST CENTRAL WISC PLUS SOME SCT-
BKN080. THE SCT-BKN CLOUDS WILL CONTINUE ROTATING THROUGH WESTERN
WISC AND FOG SHOULD THEREFORE HOLD OFF AT KRNH/KEAU FOR A LITTLE
WHILE...THEN GO IFR OR LIFR AFTER 08Z-09Z. GOOD CHANCE FOR LIFR
FOG IN CENTRAL AND EAST CENTRAL MN AS WELL WHERE THERE WAS SPOTTY
PRECIP TUESDAY. WILL NOT BE SURPRISED IF KSTC TO KEAU EXPERIENCES
SOME 1/4SM FOG FOR A COUPLE HOURS AROUND AND BEFORE SUNRISE. FOG
SHOULD DISSIPATE AFTER 14Z. SURFACE HIGH SHOULD BE IN FAR WESTERN
WISCONSIN AT 12Z. TIGHTENING GRADIENT SHOULD KEEP SE WINDS AROUND
10 KTS IN MN THROUGH WEDNESDAY EVENING. SURGE OF PRECIP SHOULD
ARRIVE IN WESTERN MN WED EVE WITH THUNDERSTORMS A DECENT BET.

KMSP...
FOG IS ANTICIPATED...AND SHOULD CERTAINLY BE AROUND 4-5SM...BUT
CONFIDENCE IS NOT GREAT THAT VISIBILITY WILL DROP BELOW 3SM
WEDNESDAY MORNING. IN PART BECAUSE OF CURRENT TEMP/DPT SPREADS AND
LIGHT NNE WIND. SATELLITE AIRPORTS WILL CERTAINLY HAVE SOME DENSE
FOG. SURFACE HIGH DEPARTS WEDNEDAY MORNING AND SE WIND WILL REMAIN
NEARLY CONSTANT THROUGH THE AFTERNOON. SOME CU SHOULD DEVELOP
AROUND MIDDAY...THEN STORMS MAY MOVE IN LATE WED NIGHT.

/OUTLOOK FOR KMSP/
THU...VFR. CHC MVFR WITH TSRA...ESPECIALLY IN THE MORNING.
WINDS SE 5-10 KTS BECMG SW.
FRI...VFR. SLGT CHC MVFR WITH TSRA. WINDS NE 5-10 KTS.
SAT...VFR. CHC MVFR WITH TSRA. WINDS SW 5-10 KTS BCMG NW.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

SHORT TERM...LS
LONG TERM...DWE
AVIATION...TDK






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