Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 190243
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
943 PM CDT FRI APR 18 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 239 PM CDT FRI APR 18 2014

EARLY AFTERNOON SURFACE ANALYSIS IDENTIFIED AN AREA OF LOW PRESSURE
ACROSS THE HIGH PLAINS...WITH HIGH PRESSURE CENTERED OVER ONTARIO.
THE NORTH/SOUTH PRESSURE GRADIENT ACROSS THE UPPER MIDWEST RESULTED
IN EAST SOUTHEAST WINDS...WITH HIGHER GUSTS NEAR THE MN/DAKOTA
BORDER. OVER THE NEXT 24 HOURS THE UPPER LEVEL PV ANOMALY DRIVING
THIS SURFACE LOW WILL SKIRT EASTWARD ACROSS THE INTERNATIONAL
BORDER. THE SURFACE FEATURES WILL MIRROR THE EASTWARD
PROPAGATION...WITH A TRAILING COLD FRONT FORECAST TO MOVING DOWN
FROM THE NORTHWEST THROUGHOUT THE DAY ON SATURDAY.

FORECAST SOUNDINGS SHOW MID LEVEL SATURATION...WITH SOME ELEVATED
CAPE...SO SHOULD SEE A LINE OF RADAR RETURNS ALONG THE
AFOREMENTIONED COLD FRONT. HOWEVER...THE LOW LEVEL CONVERGENCE
GRADUALLY WEAKENS WITH TIME...AND THE BEST UPPER LEVEL FORCING FOR
ASCENT WILL BE FOCUSED NORTH OF THE FORECAST AREA. THEREFORE NOT
EXPECTING WIDESPREAD PRECIP BUT SHOULD SEE A FEW SCATTERED SHOWERS
SO HAVE CONTINUED A CHANCE FOR PRECIP ON SATURDAY. THE MID LEVEL
CLOUDS THAT WILL ACCOMPANY THE FRONT WILL MITIGATE AFTERNOON
HIGHS...BUT THE DEEP BOUNDARY LAYER MIXING SHOULD RAISE TEMPS NEAR
70 ACROSS SOUTHERN MN...AND NEAR 60 ACROSS THE NORTH. IF THE MID
LEVEL CLOUDS WERE ABSENT FROM THIS FORECAST...TEMPERATURES WOULD
EASILY CLIMB INTO THE MID 70S ACROSS MUCH OF THE REGION.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 239 PM CDT FRI APR 18 2014

ZONAL FLOW AT THE START OF THE PERIOD WILL AMPLIFY BY MIDWEEK...
BUT REMAIN FAIRLY PROGRESSIVE THROUGH THE BALANCE OF THE FORECAST
PERIOD. THIS WILL RESULT IN FAIRLY ACTIVE WEATHER THROUGH THE
UPCOMING WORKWEEK... ALTHOUGH THE MORE SIGNIFICANT WEATHER SHOULD
BE DURING THE SECOND HALF OF THE WEEK AS A DECENT SURFACE LOW AND
UPPER WAVE MAKE THEIR WAY INTO THE UPPER MIDWEST. THE ECMWF AND
GFS ARE IN GOOD AGREEMENT ON THE OVERALL EVOLUTION OF LARGE SCALE
FEATURES THROUGH THE WEEK... WITH THE LATEST GFS MORE IN LINE
WITH THE ECMWF IN TERMS OF BEING A BIT MORE PROGRESSIVE THAN IT
WAS WITH THE SYSTEM FOR THE SECOND HALF OF THE WEEK. HOWEVER...
NEITHER IS EXACTLY FAST WITH THAT FEATURE... WHICH MEANS WE/LL
HAVE AN EXTENDED PERIOD OF TIME WITH POPS IN THE FORECAST DURING
THAT TIME FRAME.

THE FRONTAL BOUNDARY WHICH MOVES THROUGH ON SATURDAY LOOKS TO HANG
UP JUST TO OUR SOUTHEAST FOR AN EXTENDED PERIOD OF TIME FROM
SATURDAY NIGHT INTO MONDAY AS THE MAIN MID-UPPER FLOW SHIFTS A BIT
NORTH AND IS ESSENTIALLY PARALLEL TO THE OLD BOUNDARY. THIS WILL
KEEP THE FAR EAST/SOUTHEAST PORTION OF THE AREA UNDER THE GUN FOR
CHANCES OF PCPN THROUGH SUNDAY NIGHT. WILL CONTINUE TO INCLUDE A
MENTION OF THUNDER WITH 850-500MB DIFFERENTIAL THETA-E HOVERING
NEAR/BELOW ZERO ACROSS THAT AREA. HIGH PRESSURE SHOULD
SUFFICIENTLY ASSERT ITSELF BY MONDAY TO PUSH ANY LINGERING PCPN
SOUTH/EAST OF THE AREA... WITH FAIR AND DRY WEATHER LINGERING
THROUGH TUESDAY. RETURN FLOW WILL SETUP ON THE BACKSIDE OF THE
HIGH TUESDAY NIGHT INTO WEDNESDAY... WITH DECENT MOISTURE
TRANSPORT AND WARM ADVECTION INDICATED BY THE GFS AND ECMWF BY
WEDNESDAY NIGHT INTO THURSDAY. THIS LOOKS TO BE ACCOMPANIED BY
SOME CONVECTIVE INSTABILITY AS WELL... SO A MENTION OF THUNDER
WILL NEED TO ACCOMPANY THE ELEVATED POPS. SHOULD WE GET MORE
ROBUST SOUTHERLY FLOW THAN EXPECTED WE MIGHT NEED TO THINK MORE
ABOUT THE POTENTIAL FOR STRONG STORMS... BUT AT THIS POINT THE
BETTER INSTABILITY STILL LOOKS LIKE IT WILL STAY SOUTH OF OUR
AREA. WE SHOULD SEE A COLD FRONT PUSH THROUGH BY FRIDAY... BUT THE
UPPER TROUGH AND SURFACE LOW WILL LOITER OVER THE REGION...
NECESSITATING A CONTINUATION OF SOME CHANCE POPS INTO FRIDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY EVENING)
ISSUED AT 930 PM CDT FRI APR 18 2014

THERE IS CHANCE FOR TWO ROUNDS OF SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS OVER THE NEXT 24 HOURS...HOWEVER...EVEN WITH THE
CHANCE FOR RAIN WE ARE STILL EXPECTING MAINLY VFR CONDITIONS
THROUGH TOMORROW. THE FIRST ROUND OF SHOWERS WILL ARRIVE EARLY
TOMORROW MORNING AND SHOULD MOVE FROM WEST CENTRAL...TO
CENTRAL...TO NORTHWEST WI. THERE IS THE POTENTIAL FOR THUNDER AT
KSTC AND KAXN WITH THE EARLY ROUND. A SECOND ROUND OF SHOWERS AND
POSSIBLY ISOLATED THUNDERSTORMS IS EXPECTED FROM THE LATE MORNING
INTO THE AFTERNOON ALONG A COLD FRONT THAT WILL PASS THROUGH THE
TAF SITES. THERE COULD BE A 2-3 PERIOD OF MAINLY LIGHT RAIN WITH
THE AFTERNOON SHOWERS. OTHERWISE...WE WILL SIMPLY MAINTAIN VFR
CONDITIONS /BKN-OVC HIGH CLOUDS/ AND STRONG SOUTHEAST WINDS.

KMSP...

WE THINK MOST OF THE EARLY MORNING SHOWER ACTIVITY AND CHANCE FOR
THUNDERSTORMS WILL REMAIN 40-60 MILES W-NW OF THE AIRPORT. THAT
BEING SAID...THE RISK FOR THUNDER AROUND OR JUST BEFORE SUNRISE
TOMORROW CAN NOT BE COMPLETELY RULED OUT. THERE IS A BETTER CHANCE
FOR LIGHT RAIN AND A BRIEF WINDOW FOR MVFR CONDITIONS DURING THE
AFTERNOON. WINDS WILL INCREASE AND SLOWLY VEER EARLY IN THE
MORNING.

/OUTLOOK FOR KMSP/

SAT NIGHT...SLIGHT CHC MVFR WITH -SHRA. WINDS SW BCMG NW 5-10 KTS
LATE.
SUN...VFR. WINDS NNE 5 KTS.
MON...VFR. WINDS NW 5-15 KTS.

&&

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

$$

SHORT TERM...JRB
LONG TERM...
AVIATION...CLF







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