Area Forecast Discussion
Issued by NWS Twin Cities, MN

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150
FXUS63 KMPX 151814
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
114 PM CDT FRI MAY 15 2015

.UPDATE...
ISSUED AT 114 PM CDT FRI MAY 15 2015

CLOUDS HAVE BEEN SLOW TO BUDGE TODAY THANKS TO THE LIGHT WINDS AND
LIMITED MIXING WITH THE SFC RIDGE PUSHING DOWN. DO NOT THINK WE
WILL SEE MUCH IN THE WAY OF SUN TODAY...SO HAVE UPPED SKY GRIDS
THROUGH THE REST OF THE DAY...ALONG WITH KNOCKING BACK HIGHS A FEW
DEGREES FROM WHAT WAS FORECAST. FOR TONIGHT 12Z MODELS HAVE SLOWED
THE ADVANCEMENT OF THE WARM FRONT ACROSS THE AREA...SO HAVE BEGUN
THE PROCESS OF SLOWING DOWN THE NE ADVANCEMENT OF POPS TONIGHT.
HAVE ALSO STARTED TO NUDGE PRECIP CHANCES DOWN AS WELL AS WE JUST
ARE NOT SEEING A CLEAR SIGNAL FROM ANY OF THE CAMS ON SEEING
CONVECTION TONIGHT. THE BIG ISSUE LOOKS TO BE THE FACT THAT THE
850 WINDS BRINGING IN THE INCREASED TEMPS/MOISTURE LOOK TO BE
DIFFLUENT ACROSS THE AREA...WHICH IS USUALLY AN INHIBITOR FOR
PRECIP DEVELOPMENT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 403 AM CDT FRI MAY 15 2015

SHORT TERM CONCERNS DEAL WITH FOG...LOCALLY DENSE FOG WHERE SKIES
TEMPORARILY CLEARED OUT...AND HOW LONG WILL THE CLOUDS LINGER
CAUSING TEMPS TO BE A FEW DEGREES COOLER THAN FORECAST. OTHER
CONCERNS DEAL WITH SCATTERED SHRA/TSRA DEVELOPING ALONG AN ADVANCING
WARM FRONT LATER TONIGHT.

FIRST...WIDESPREAD DENSE FOG IS NOT EXPECTED BASED ON CLOUD COVER
AND DEPTH OF THE CLOUD COVER HOLDING THRU MID MORNING. A FEW
LOCATIONS WHERE SKIES CLEARED WILL SEE LOCALIZED DENSE FOG BUT NOT
ENOUGH TO WARRANT A DENSE FOG ADVISORY. SECONDLY...THE CLOUD DEPTH
IS STILL FAIRLY DEEP /UP TO 5K/ BUT THE HIGH SUN ANGLE IN MAY SHOULD
ALLOW FOR SKIES TO BECOME PARTLY CLOUDY BY THE AFTN.
INITIALLY...SKIES WILL LIKELY BE CLOUDY OR MOSTLY CLOUDY THRU
MID/LATE MORNING. TEMPS REFLECT THIS TREND WITH TEMPS SLOWLY RISING
IN THE MORNING...WITH A MORE ABRUPT UPWARD TREND BY THE EARLY AFTN.

NOT MUCH CHANGE FOR TONIGHTS FORECAST AS THE ADVANCING WARM FRONT IS
EXPECTED TO BRING WIDELY SCATTERED SHRA/TSRA BEGINNING THIS EVENING
IN THE SW...AND SPREADING N/NE ACROSS THE CWA. HOWEVER...BASED ON
THE LLJ ORIENTATION AND DIVERGENT FLOW IN THE BOUNDARY LAYER IN MPX
N/NE CWA...THERE SHOULD BE A GRADUAL CUTOFF ON THE CHC/S OF
MEASURABLE PRECIPITATION ACROSS CENTRAL/EC MN AND WC WI. THE BEST
CHANCE OF MEASURABLE PRECIPITATION WILL OCCUR IN THE FAR SW/WC PARTS
OF MN WHERE BETTER MOISTURE ADVECTION AND CONVERGENCE IS MAXIMIZED.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 403 AM CDT FRI MAY 15 2015

THE FOCI IN THE LONG TERM REMAINS ON SEVERE WEATHER CHANCES OVER
THE WEEKEND...FOLLOWED BY COOLER TEMPERATURES FOR NEXT WEEK.

WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL LIKELY BE ONGOING
SATURDAY MORNING GIVEN THE WARM FRONT WILL HAVE LIFTED ACROSS THE
AREA. SHOULD SEE ADEQUATE SCOURING OF THE LOW CLOUDS TO ALLOW
TEMPERATURES TO MODERATE INTO THE UPPER 70S TO LOWER 80S RANGE ON
SATURDAY...GIVEN BREEZY SOUTHERLY WINDS IN THE WARM SECTOR WILL
PROVIDE AMPLE MIXING. BY LATE AFTERNOON...MODERATE DESTABILIZATION
IS ANTICIPATED GIVEN THE AFOREMENTIONED WARMING COUPLED WITH
SURFACE DEWPOINT MODERATION INTO THE UPPER 50S TO LOWER 60S RANGE.
EXPECT TO SEE RENEWAL OF THUNDERSTORM ACTIVITY TO THE WEST IN
CLOSER PROXIMITY TO THE TRIPLE POINT AND ADVANCING MID/UPPER
SHORTWAVE TROUGH. DURING THE EVENING...EXPECT SAID ACTIVITY TO
MARCH ACROSS WEST/CENTRAL MN...EXPANDING TO THE INTERSTATE 35
CORRIDOR BY MIDNIGHT SUNDAY MORNING. THIS ROUND OF EVENING
CONVECTION COULD PRODUCE DAMAGING WINDS AND LARGE HAIL GIVEN SHEAR
PROFILES AND MID LEVEL LAPSE RATES...PRIMARILY OVER WESTERN
MINNESOTA.

ON SUNDAY...THE KEY FACTOR THAT WILL DETERMINE STORM SEVERITY WILL
BE THE EXTENT OF ATMOSPHERIC DESTABILIZATION IN THE WAKE OF THE
NOCTURNAL CONVECTION. SHEAR WILL BE PLENTIFUL GIVEN THE FRONT AND
SHORTWAVE TROUGH...BUT INSTABILITY COULD PROVE INSUFFICIENT FOR
SEVERE STORMS.

SUNDAY NIGHT INTO MONDAY BRINGS DEFORMATION PRECIP TO THE AREA AS
THE SURFACE LOW LIFTS TO THE GREAT LAKES. SHOULD BE A BREEZY
PERIOD AS WELL...GIVEN THE TIGHT PRESSURE GRADIENT WITH THE LOW.

IN THE WAKE OF THE TROUGH...BROAD HIGH PRESSURE SETTLES IN FOR
NEXT WEEK. COOLER TEMPERATURES AND A TREND TOWARD DRY WEATHER WILL
ENSUE. HIGHS WILL TOP OUT IN THE 50S ON MONDAY AND TUESDAY...THEN
GRADUALLY MODERATE TO AROUND 70 DEGREES FOR HIGHS BY FRIDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 114 PM CDT FRI MAY 15 2015

MODELS DID NOT HANDEL THE PROLONGED RESIDENCE TIME OF THE MVFR
CIGS VERY WELL TODAY...AND WITH LIGHT WINDS LIMITING
MIXING...THESE CIGS WILL BE WITH US A BIT LONGER. CONFIDENCE IS
LOW IN IMPROVEMENTS TO VFR IN THE TAFS...AS IT COULD HAPPEN
EARLIER OR EVEN MUCH LATER THAN CURRENTLY INDICATED. WARM FRONT
RIGHT NOW IS STILL DOWN ALONG THE I-70 CORRIDOR...SO THE SLOWING
OF ITS ARRIVAL WITH GUIDANCE TONIGHT MAKES SENSE. TSRA COVERAGE
THROUGH 18Z SAT LOOKS SCT AT BEST...AND CONFIDENCE IN WHEN/WHERE
STORMS MAY BE IS TOO LOW AT THIS POINT TO INCLUDE ANY PRECIP
MENTION IN A POINT SPECIFIC FORECAST. ALONG WITH THE WARM
FRONT...SREF PROBS SHOW MVFR CIGS COMING UP AS WELL...THOUGH
THOSE PROBS ARE HIGHEST IN WRN MN...WHICH IS WHY AXN/RWF ARE THE
ONLY TWO TERMINALS WHERE MVFR CIGS WERE BROUGHT BACK IN SATURDAY
MORNING. AS FOR WINDS...THEY WILL BE LIGHT AND VRB TODAY AS THE
HIGH MOVES THROUGH...BUT SHOULD SEE SE WIND GUSTS UP OVER 20 KTS
BY 18Z SAT IN MN AS PRESSURE GRADIENT INCREASES IN RESPONSE TO A
SUB-1000MB LOW DEEPENING OVER WRN SODAK.

KMSP...CONFIDENCE ON GOING VFR WITH CIGS AT 21Z IS LOW. BASED ON
HOW EXPANSIVE THE MVFR CIGS ARE...WOULD SAY CHANCES OF THE CIGS
IMPROVING LATER THAN 21Z IS BETTER THAN IT HAPPENING BEFORE 21Z.
FOR TONIGHT...REMOVED ANY PRECIP MENTION...THOUGH WE COULD SEE
SOME ISO/SCT TSRA ACTTIVITY SAT MORNING AS THE WARM FRONT LIFTS
NORTH. CONFIDENCE IS JUST NOT HIGH ENOUGH IN IF/WHEN/WHERE
ACTIVITY WILL BE TO INCLUDE IN A TAF AT THIS POINT. SAT
AFTERNOON...PLENTY OF INSTABILITY WILL BE PRESENT...BUT WE LACK
MUCH IN THE WAY OF A FORCING MECHANISM TO GET STORMS GOING...THAT
LOOKS TO ARRIVE LATER SAT NIGHT...SO KEPT PRECIP MENTION OUT OF
THE TAF SAT AFTERNOON AS WELL.

/OUTLOOK FOR KMSP/
SUN...VFR WITH SCATTERED IFR/TSRA. WINDS S AT 15-25 KTS.
MON...VFR. WINDS NW AT 15-25 KTS.
TUE...VFR. WINDS N AT 10 KTS.

&&

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

$$

UPDATE...MPG
SHORT TERM...LS
LONG TERM...JLT
AVIATION...MPG



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