Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 070850
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
350 AM CDT THU MAY 7 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT THU MAY 7 2015

THE SHORT TERM CONCERNS ARE TIMING AND EXTENT OF CONVECTION AND
TEMPERATURES.

WATER VAPOR IMAGERY IS SHOWING SHORT WAVE TROUGH EXTENSION ACROSS
SOUTHEAST SOUTH DAKOTA INTO IOWA THIS MORNING.  AREA OF SHOWERS AND
THUNDERSTORMS ASSOCIATED WITH THIS FEATURE...MOSTLY CONCENTRATED
ACROSS NORTHWEST IOWA/SOUTHWEST MINNESOTA.  SPC MESOSCALE ANALYSIS
SHOWING DECENT 850MB MOISTURE TRANSPORT AHEAD OF THE TROUGH...WITH
MORE SHOWERS AND ISOLATED THUNDER DEVELOPING OUT ACROSS CENTRAL MN.
THIS SHOULD CONTINUE TO BE THE TREND AS THIS TROUGH LIFTS
NORTHEAST...AND THE MOISTURE TRANSPORT MAXIMIZES OVER MN.  EXPECT AT
LEAST LIKELY POPS AS THIS LIFTS NORTHWEST.  THE LATEST HRRR FORECAST
REFLECTIVITY SHOWS THIS TREND AS WELL.

CLOUDS ARE EXPECTED TO REMAIN...THOUGH SOME EROSION MAY OCCUR LATE
THIS MORNING BEFORE CONVECTION REFIRES...OR ENHANCES ONCE AGAIN.
DAY1 OUTLOOK HAS EXPANDED THE MARGINAL SEVERE WEATHER RISK OUT AHEAD
OF THE COLD FRONT.  THIS WILL BE FOR THE AFTERNOON/EARLY EVENING
EAST OF THE COLD FRONT.  STEEP LAPSE RATES INDICTED AND DEPENDING
HOW MUCH HEATING TAKES PLACE...MODEL FORECAST SURFACE BASED CAPE
INCREASING TO 1500 J/KG.  BULK SHEAR IS FORECAST TO RANGE 35-40KTS
ALONG AND EAST OF THE FRONT...WHICH WOULD BE ENOUGH FOR THE
POSSIBILITY OF HAIL AND STRONG WINDS WITH THE STRONGER CONVECTION.
THE MODELED UPDRAFT HELICITY WAS INDICATING THE MAIN THREAT OVER
WEST CENTRAL WISCONSIN...WITH WHAT APPEARS TO BE A LEADING SURFACE
TROUGH. WILL HAVE TO MONITOR CLOUD TRENDS AND SEE IF INDEED
INSTABILITY WILL INCREASE ENOUGH TO GENERATE A SMALL SEVERE WEATHER
RISK OVER THE EASTERN CWA.

THE FRONT MOVES INTO WESTERN WISCONSIN THIS EVENING AND SHOULD TAKE
THE BULK OF THE SHOWERS WITH IT.  THERE IS SOME THREAT OF MID LEVEL
SHRA DEVELOPING BEHIND THE COLD FRONT INTO CENTRAL MN LATER TONIGHT.
THE MODELS WERE INDICATING SOME STRONGER MID LEVEL FGEN.  BUT IT
REMAINS TO BE SEEN IF THERE WILL BE ENOUGH MOISTURE TO CONTINUE THE
SHOWER THREAT.  STILL MAINTAINED THE SMALL CHANCE POPS AFTER 06Z
FRI FOR NOW.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 350 AM CDT THU MAY 7 2015

BY FRIDAY MORNING...THE AFOREMENTIONED COLD FRONT AND SURFACE LOW
RESPONSIBLE FOR THE RAIN IN THE SHORT TERM WILL BE EAST OF THE
FORECAST AREA. HIGH PRESSURE WILL BUILD IN ACROSS THE NORTHERN
HIGH PLAINS ON FRIDAY AND INTO THE UPPER MISSISSIPPI RIVER VALLEY
ON SATURDAY. THE POST FRONTAL AIR MASS ON FRIDAY WILL BE QUITE
COOL WITH TEMPERATURES IN CENTRAL/NORTHERN MN LIKELY REMAINING IN
THE 50S DURING THE AFTERNOON. WE MIGHT EVEN BE A LITTLE TOO WARM
WITH FRIDAY`S TEMPERATURES...ESPECAILLY GIVEN THE DECENT CHANCE
FOR A BROKEN TO OVERCAST DECK OF MID CLOUDS. THE WEATHER SHOULD
REMAIN DRY ON FRIDAY. ON SATURDAY...A WEST COAST TROUGH WILL EJECT
EAST OUT OF CALIFORNIA AND PASS OVER THE ROCKIES BEFORE SLOWLY
MAKING ITS TRACK ACROSS THE REGION SUN-TUE. A SURFACE LOW IS
FORECAST TO TRACK FROM THE CENTRAL PLAINS...ACROSS IA...AND
EVENTUALLY REACHING EASTERN LAKE SUPERIOR BY TUESDAY. THAT PUTS
MN/WI IN A PRETTY GOOD SPOT FOR WIDESPREAD RAIN SUNDAY INTO
MONDAY. THE 06.18Z AND 07.00Z RUNS OF THE GFS DEPICT SIMILIAR
SOLUTIONS...A CHANGE FROM THE FEW RUNS BEFORE THESE LAST TWO WHICH
HAD A LOT OF RUN-TO-RUN VARIABILITY IN HOW IT HANDLED THE
PROGRESSION OF THIS SURFACE LOW EARLY NEXT WEEK. THE GFS IS
HEAVIER WITH THE QPF WHEN COMPARED TO THE ECMWF...BECAUSE IT IS
ALSO SLOWER...DEEPER...AND FARTHER SOUTH THAN THE ECMWF. THE ECMWF
HAS ALSO HAD A COUPLE RUNS NOW WITH BETTER CONSISTENCY. WE TRENDED
THE TEMPS A BIT COOLER MON-WED...WITH THE FREEZING LEVEL JUST A
COUPLE THOUSAND FEET OFF THE GROUND TUE-WED. TEMPERATURES REALLY
DO NOT START TO MODIFY UNTIL AT LEAST THURSDAY. SO...MN/WI IS IN
FOR A COOL WEEK AFTER THE RAIN MOVES TUE-TUE NIGHT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 1020 PM CDT WED MAY 6 2015

WAITING FOR THE NEXT BATCH OF SHOWERS AND THUNDERSTORMS TO LIFT
NORTHEAST FROM EASTERN NE AND NORTHWEST IA. THIS ACTIVITY WILL
WANE A BIT...BUT WILL OVERSPREAD THE AREA LATE TONIGHT AND
THURSDAY MORNING. BKN-OVC MVFR CIGS WILL DEVELOP AS THIS AREA
ARRIVES. THEN EXPECT A BREAK DURING THE AFTERNOON...WITH
POTENTIAL FOR MORE DEVELOPMENT /THUNDERSTORMS/ LATE AFTERNOON.
SOUTHEAST WINDS SHIFT TO THE SOUTHWEST ON THURSDAY...THEN TO THE
NORTHWEST ON THURSDAY EVENING. SPEEDS AOA 12KTS THROUGH THE
PERIOD.

KMSP...
MAINLY DRY OVERNIGHT...UNTIL NE/IA BATCH OF PRECIPITATION MOVES
IN. EXPECT THIS AROUND/AFTER 12Z...PERSISTING THROUGH THE MORNING
ALONG WITH MVFR CONDITIONS /BUT SHOULD STAY ABOVE 1700 FT/. BRIEF
BREAK IN THE EARLY AFTERNOON...THEN REDEVELOPMENT /POSSIBLY WITH
THUNDER/ OCCURS BY LATE AFTERNOON.

/OUTLOOK FOR KMSP/
FRI...VFR. WINDS NW 10 KTS.
SAT...VFR. WINDS NE 10 KTS.
SUN...MVFR LIKELY WITH IFR POSSIBLE IN SHWRS/TSTMS. WINDS NE 10-15
KTS.


&&

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

$$

SHORT TERM...DWE
LONG TERM...CLF
AVIATION...LS


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