Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 280122
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
822 PM CDT WED APR 27 2016

.UPDATE...
ISSUED AT 653 PM CDT WED APR 27 2016

UPDATED TO INCLUDE 00Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 346 PM CDT WED APR 27 2016

CLOUDS WILL STICK AROUND THROUGH THURSDAY EVENING AS THE UPPER
LEVEL SYSTEM SLOWLY MIGRATES EASTWARD. A BAND OF RAIN WILL LIFT
NORTHWARD THIS EVENING AND SLOWLY DISSIPATE...BUT SHOWERS WILL
REDEVELOP OVERNIGHT BEFORE TAPERING OFF THROUGH THE DAY TOMORROW.

EARLY AFTERNOON WATER VAPOR IMAGERY WITH GFS 500MB HEIGHTS AND
WINDS SHOWED A POSITIVELY TILTED SHORTWAVE ACROSS THE CENTRAL
CONUS...WITH AN OCCLUDED STRUCTURE IN THE CLOUD FIELD. A CLOSER
LOOK AT THE MASS FIELDS REVEALED THAT THIS INDEED WAS AN OCCLUDED
SYSTEM. THE DRY SLOT WRAPPING AROUND FROM THE SOUTHWEST TOGETHER
WITH THE LATE APRIL SOLAR RADIATION ALLOWED THE WARM SECTOR OF THE
SURFACE LOW TO QUICKLY REESTABLISH ITSELF THIS AFTERNOON...AND AS
A RESULT A FEW MINI-SUPERCELLS WITH TORNADOES WERE ONGOING ACROSS
SOUTHWEST IA.

CLOSER TO HOME A BAND OF MODERATE RAIN WAS SLOWLY LIFTING
NORTHWARD ACROSS THE REGION...BUT THERE WAS NOT ANY INSTABILITY
SO THERE IS NO LIGHTNING WITH THIS BAND OF PRECIPITATION. AS THE
UPPER LEVEL FORCING SLOWLY WANES ACROSS THE REGION THE RAIN SHOULD
DISSIPATE...BUT ADDITIONAL AREAS OF POSITIVE VORTICITY WILL ROTATE
ACROSS THE REGION AND ALLOW SCATTERED SHOWERS TO REDEVELOP DURING
THE OVERNIGHT HOURS. FORECAST SOUNDINGS SHOW LOW LEVEL SATURATION
THROUGH THURSDAY...SO CONTINUED WITH CLOUDY TO MOSTLY CLOUDY
SKIES.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 346 PM CDT WED APR 27 2016

AN UPPER RIDGE/BLOCKING HIGH OVER SOUTH CENTRAL CANADA WILL BE THE
MAIN INFLUENCE IN THE EXTENDED PERIOD FROM FRI/SAT/SUN AS A
SIMILAR STORM SYSTEM THAT IS AFFECTING THE CENTRAL PLAINS
TODAY...MOVES OUT INTO THE PLAINS LATE THIS WEEK/WEEKEND WITH
SIMILAR RAIN SHIELD/AIR MASS CONSISTENCIES. BASED ON THE STRONGER
INFLUENCE OF THE UPPER RIDGE...MODELS HAVE BEEN SLOWLY DRYING THE
AIR MASS ACROSS THE UPPER MIDWEST FOR FRI/SAT/SUN SYSTEM. WITH A
PERSISTENT OR DEVELOPING EAST- NORTHEAST WIND IN THE BOUNDARY
LAYER...UP TO 5K...THIS WILL ERODE ANY BOUNDARY LAYER MOISTURE
FROM MOVING NORTHWARD. THEREFORE...THE BEST CHANCE OF MEASURABLE
RAINFALL WILL OCCUR NEAR THE IOWA/MN BORDER...WITH LESSER OR NO
AMOUNTS IN CENTRAL MN. THIS IS AGAIN BASED ON THE MAIN INFLUENCE
OF THE UPPER RIDGE IN CANADA. IF THIS RIDGE DECIDES TO WEAKEN OR
RETROGRADE TO THE WEST...THIS MAY ALLOW FOR A WETTER WEEKEND THAN
EXPECTED.

IN ADDITION TO THE RAINFALL CHANCES OR LACK THEREOF...THE EAST-
NORTHEAST FLOW WILL KEEP TEMPERATURES FROM RISING TOO MUCH. IT MAY
EVEN BE COOLER THAN FORECAST. EVENTUALLY AS THIS SYSTEM MOVES
EAST ACROSS THE OHIO VALLEY EARLY NEXT WEEK...TEMPERATURES WILL
SLOWLY MODERATE.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 653 PM CDT WED APR 27 2016

MAIN BATCH OF RAIN PUSHING N OF I-94 AT INITIALIZATION TIME...WITH
CONDS GENERALLY STILL IN VFR RANGE THOUGH OCNL MVFR CAN BE FOUND.
AFTER ABOUT A 4-6 HR BREAK...ADDITIONAL RAIN IS EXPECTED OVERNIGHT
BUT CONDS ARE LIKELY TO REMAIN IN VFR RANGE. A FEW OBS OF MVFR
VSBY AND/OR CEILING CANNOT BE RULED OUT...BUT IT IS NOT EXPECTED
TO LAST LONG IF AT ALL. RAIN LOOKS TO EXIT THE AREA BY MID-AFTN
TMRW WITH CEILINGS STEADILY RISING. WINDS TO REMAIN OUT OF THE ENE
WITH SPEEDS DIMINISHING TO THE 5-10 KT RANGE.

KMSP...NEXT BATCH OF RAIN MAY CONTAIN OCNL MVFR CONDS...BUT VFR
CONDS LOOK TO PREVAIL FOR THE MORNING PUSH AND THEREAFTER.

/OUTLOOK FOR KMSP/
FRI...VFR. WIND E AT 05KT.
SAT...VFR. WIND ENE AT 10G20KT.
SUN...VFR. WIND NE AT 10G15KT

&&

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

$$

UPDATE...JPC
SHORT TERM...JRB
LONG TERM...JLT
AVIATION...JPC



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