Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 131650
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1150 AM CDT SUN APR 13 2014

.MESOSCALE DISCUSSION...
ISSUED AT 1128 AM CDT SUN APR 13 2014

INTERESTING SCENARIO DEVELOPING THIS AFTN WITH STRONG CAA AND
DRYING BLW 3K...AND STRONG FRONTOGENESIS ABV 85H RISING N/NE
ACROSS MPX FAR SE CWA. SEVERAL WEAK CIRCULATION ARE NOTED IN
REGIONAL RADAR ACROSS IA/NE WITH SFC OBS INDICATED THAT -SN/UP WAS
DEVELOPING IN NW IA. MEAN LAYER WET BULB TEMPS BLW 1KM HAVE
DROPPED TO NEAR +1C AS CLOSE AS KFSD. SO WITH THE CONTINUED STRONG
CAA AND ASSOCIATED DRIER AIR...THERE COULD BE MORE SNOW DEVELOPING
EARLIER THAN EXPECTED OVER PORTIONS OF SC MN BY MID/LATE AFTN.
THIS IS HIGHLY DEPENDENT ON THE STRENGTH OF THE CAA/DRIER AIR AND
WHETHER THE FORCING ABV 85H CAN OVERCOMPENSATE IT. FORECASTERS
THIS AFTN/EARLY EVENING WILL NEED TO PAY ATTENTION TO SFC OBS AND
WHETHER THE COLDER AIR HAS ALREADY ARRIVED.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT SUN APR 13 2014

LOOKS LIKE THE FORECAST AREA WILL REMAIN SHROUDED IN CLOUD COVER
TODAY BUT A VAST MAJORITY OF THE RAINFALL EXPECTED TODAY WILL FALL
ACROSS IOWA AND SOUTHERN WISCONSIN. OTHERWISE...NEAR STEADY TEMPS
ARE EXPECTED TODAY WITH COOLER AIR ADVANCING FROM THE NORTH.

THE CENTER OF THE SURFACE LOW IS CENTERED OVER THE PANHANDLE OF
OKLAHOMA EARLY THIS MORNING. THE NAM/ECMWF SEEM TO BE JUST SLIGHTLY
BETTER WITH THE 06-HR FORECAST LOCATION WHEN COMPARED TO THE
GFS...WHICH SEEMS JUST A BIT TOO FAR NORTH. THE MAINLY LIGHT RADAR
RETURNS ONGOING IN SD AND NE IS COLLOCATED WITH STRONG 850-700MB FGEN
- THERE IS GOOD COLD ADVECTION ONGOING IN SD/ND. THE AVAILABLE
SHORT-TERM MODEL GUIDANCE WEAKENS THIS AREA WITH TIME AND REFOCUSED
THE PRECIP FARTHER SOUTHEAST AS THE LOW BEGINS TO SLIDE
EAST-NORTHEAST. CONVECTION CONTINUES IN IOWA WHERE THE REMAINS TO BE
GOOD 925-850MB MOISTURE TRANSPORT. COUNTIES NEAR THE IA/MN BORDER IN
SOUTHERN MN ARE IN A MORE FAVORABLE POSITION TO SEE LIGHT RAIN BY
THE LATE MORNING AND ON INTO THE AFTERNOON. THE RAIN SHOULDN`T BE
HEAVY WITH THE THUNDERSTORM ACTIVITY REMAINING OFF TO THE SOUTH. EVEN
WHERE IT DOES RAIN IN THE FORECAST AREA TODAY...AMOUNTS WILL
GENERALLY BE LESS THAN 0.10". IN TERMS OF P-TYPE...SNOW IS NOT
IMPOSSIBLE TODAY...ESPECIALLY IN THE MID TO LATE AFTERNOON WHEN
FORECAST SOUNDINGS COOL ENOUGH TO PRODUCE SNOWFLAKES JUST OFF THE
SURFACE. WE DON`T EXPECT BELOW FREEZING TEMPS WHEN THE PRECIP IS
FALLING. ON THE CONTRARY...WE THINK 37-44 IS A MORE REASONABLE
TEMPERATURE RANGE WHEN THE PRECIP IS OCCURRING AND IT IS REALLY
TOUGH TO GET SNOW WITH TEMPS THAT WARM...UNLESS THE NEAR SURFACE
WARM LAYER IS REALLY SHALLOW OR WE GET HEAVY PRECIP AND THE WET BULB
TEMPERATURE BECOMES IMPORTANT. WE THINK THE NEAR SURFACE WARM LAYER
WILL REMAIN WARM ENOUGH FOR RAIN LONG ENOUGH TO SEE MOST OF THE
PRECIP EXIT. THE GFS SOUNDINGS SHOW A QUICKER TRANSITION TO SNOW IN
SOUTH CENTRAL AND SOUTHWEST MN THIS AFTERNOON...BUT THE RAP/NAM DO
NOT SHOW THIS AND KEEP TEMPERATURES ABOUT 3-4 DEGREES TOO WARM FOR A
COMPLETE AND EARLY CHANGE OVER TO SNOW. SO IN SUMMARY...MUCH HIGHER
CONFIDENCE IN A LIGHT RAIN EVENT IN FAR SOUTHERN MINNESOTA. MOST OF
CENTRAL MN AND WEST CENTRAL WI WILL REMAIN DRY...HOWEVER...THE
TEMPERATURES WILL NOT MOVE MUCH TODAY AND THE BLUSTERY NORTH WINDS
WILL MAKE IT SEEM EVEN COOLER. TO TOP IT OFF...THERE SHOULD BE
LITTLE SUNSHINE TODAY.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 350 AM CDT SUN APR 13 2014

MONDAY THROUGH TUESDAY NIGHT...TRICKIEST ELEMENT OF THIS PERIOD WILL
CONTINUE TO BE FORECAST TEMPERATURES AS STRONG COLD AIR ADVECTION
CONTINUES MONDAY...BUT GIVES WAY TO WARM AIR ADVECTION AHEAD OF AN
APPROACHING MID-WEEK SYSTEM. THIS PERIOD WILL BE DRY ACROSS THE
AREA AS COLD AND DRY CANADIAN AIR FILLS IN ACROSS THE UPPER
MIDWEST...SO NO CHANGES WERE MADE TO THE POP FORECAST. HIGH
TEMPERATURES MONDAY WERE LOWERED FROM THE PREVIOUS FORECAST. THE
COLDEST 850H TEMPERATURES SHOW GOOD AGREEMENT AMONG THE MODELS IN
ARRIVING DURING THE DAY ON MONDAY. THIS TIME OF YEAR
THOUGH...SOLAR RADIATION WILL STILL ALLOW TEMPERATURES TO WARM AT
LEAST SLIGHTLY DURING THE DAY IN MODEST COLD AIR ADVECTION...WHICH
WILL BE THE CASE MONDAY. STARTING OFF THE DAY IN THE MID 20S...THE
COLD AIR ADVECTION WILL BATTLE RADIATIONAL HEATING AND KEEP
TEMPERATURES IN THE MID TO UPPER 30S FOR HIGHS...BASICALLY 20
DEGREES BELOW SEASONAL NORMALS...AND JUST A COUPLE DEGREES SHY OF
RECORD COLD MAXIMUMS FOR MID APRIL. IN ADDITION TO THE COLD
TEMPERATURES MONDAY...IT WILL BE QUITE WINDY WITH NORTH WINDS OF
15 TO 20 MPH, GUSTING TO 25 MPH...MAKING FOR AN UNPLEASANT SPRING
DAY. WE`LL START TO SEE THE CORE OF THE COLD MOVE EASTWARD BY
TUESDAY...BUT PLENTY OF COLD AIR WILL REMAIN. TEMPERATURE SHOULD
REACH THE 40S...WELL BELOW NORMAL. AN APPROACHING SYSTEM FROM THE
WEST WILL HAVE AN IMPACT ON HOW WARM WE GO TUESDAY AFTERNOON. THE
GFS IS FAST WITH THE SYSTEM...WHICH MEANS IT BRINGS WARM AIR
ADVECTION TO THE FA QUICKER THAN OTHER GUIDANCE. HEDGING AGAINST
THE OUTLIER IN THIS CASE...WITH THE NAM/ECMWF/UKMET IN BETTER
AGREEMENT OF A SLIGHTLY SLOWER AND WEAKER PROGRESSION.

WEDNESDAY AND WEDNESDAY NIGHT...WEDNESDAY TEMPERATURES WILL BE
HIGHLY DEPENDENT ON THE TRACK OF THE SURFACE LOW AND THE
ASSOCIATED WARM FRONT...AS A SHORTWAVE WILL DIVE FROM THE PACIFIC
NORTHWEST TUESDAY INTO WEDNESDAY. THERE HAS BEEN SOME SIGNIFICANT
DISAGREEMENT BETWEEN THE GFS/ECMWF IN HANDLING THIS SYSTEM AND
PHASING WITH A NORTHERN TROUGH. DIFFERENCES STILL REMAIN...BUT THE
GFS HAS SHIFTED ITS AXIS OF HEAVY PRECIPITATION ACROSS CENTRAL
MINNESOTA...MORE IN LINE WITH BOTH THE EC AND NAM. THE GFS
INDICATES QUITE A BIT MORE ENERGY WITH THIS SYSTEM THAN THE EC AND
NAM...AND A FASTER PROGRESSION. THE UKMET SIDES WITH THE EC AND
NAM GENERALLY. IT WAS ENCOURAGING TO SEE THE LATEST GFS RUN
RESEMBLE MORE OF AN EC/NAM SOLUTION...DESPITE BEING A LITTLE
FASTER. AREAS FROM ST. CLOUD AND NORTHWARD WILL HAVE THE HIGHEST
POPS AS MODELS ARE CONVERGING ON THE BEST FORCING THERE. AT THIS
POINT...KEPT CONSISTENT WITH A MIX OF RAIN AND SNOW...WHICH IS
DEPENDENT ON THE TIMING AS DAYTIME TEMPERATURES WOULD WARM ENOUGH
TO PRODUCE MAINLY RAIN...WHEREAS NIGHTTIME TEMPERATURES WOULD BE
MORE APT TO ALLOW SNOW DOWN TO THE SURFACE.

THURSDAY THROUGH SATURDAY...ANOTHER CANADIAN HIGH WILL BE ON THE
HEELS OF THE WEDNESDAY SYSTEM...AND POPS WERE DECREASED/TAKEN OUT
FOR THIS PERIOD GIVEN THIS DRY AIR...DESPITE A WELL DEFINED UPPER
TROUGH OVERHEAD. WHILE THE GFS AND EC HAVE POOR AGREEMENT IN
TERMS OF SHORTWAVE PLACE DURING THE REMAINDER OF THE PERIOD...BOTH
AGREE ON A GENERAL WARMING TREND BEGINNING SATURDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1128 AM CDT SUN APR 13 2014

UPSTREAM OBS/CIGS ACROSS NW/CENTRAL MN HAVE REMAINED BETWEEN 1-2K
FOR MOST OF THE MORNING. ALTHOUGH THE CONTINUED CAA AND DRIER
DWPTS SHOULD SLOWLY LIFT THE CIGS DURING THE AFTN...WILL CONTINUE
ON THE CAUTION SIDE WITH MVFR CIGS FOR MOST AREAS THRU
21-22Z...THEN BECOMING VFR OR CIGS RISING ABV 3K BY THE LATE AFTN.
THIS IS BASED ON THE CONTINUED DRIER AIR ADVECTING SOUTHWARD
ACROSS NORTHERN MN THIS AFTN. KRHN/KEAU WILL LIKELY CONTINUE WITH
THE MVFR CIGS THRU THE EVENING...BEFORE LIFTING TOWARD MONDAY
MORNING. KEAU WILL SEE RAIN/SNOW DEVELOP BY 21-23Z WITH MODERATE
RAIN AT TIMES...MIXING WITH SNOW AND CHANGING OVER TO SNOW BETWEEN
00-03Z. SOME MINOR ACCUMULATIONS WILL BE POSSIBLE BEFORE THE SNOW
ENDS IN KEAU BY 3-6Z. WINDS WILL REMAIN FROM THE N/NW THRU THE TAF
PERIOD...WITH THE CONTINUED GUSTY WINDS...BUT NOT AS STRONG BY
MONDAY LATE MORNING.

KMSP...

MAIN SHORT TERM CONCERN REMAINS THE CIGS RISING ABV 1.7K.
UPSTREAM OBS AND THE CONTINUED EXPANSION OF THE PRECIPITATION TO
THE SOUTH HAS ME WONDER IF 21Z IS TOO FAST...AND WHETHER THE
PRECIPITATION MOVES INTO MSP. BASED ON A DRIER FORECAST BLW
3K...AM LEANING TOWARD CIGS RISING TO 2K BY 21Z WITH VCSH. THIS IS
HIGHLY DEPENDENT ON THE EXPANSION OF THE PRECIPITATION FIELD
ACROSS FAR SOUTHERN MN. BY 3Z...MOST OF THE PRECIPITATION...IF TO
MAKES IT TO KMSP...WILL BE SE OF REGION. THEREFORE...CIGS WILL
BEGIN TO RISE TO VFR...BUT THE GUSTY WINDS WILL CONTINUE THRU THE
FORECAST PERIOD FROM THE N/NW.

/OUTLOOK FOR KMSP/

MON EVENING...VFR. NW WINDS LESS THAN 8 KTS.
TUE...VFR. WINDS W 5 TO 10 KT...BECG E/NE BY EVENING.
WED...MVFR WITH RA/SN POSSIBLE. WINDS E 10 TO 20 KTS...BECOMING N-NE.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...FLOOD WATCH THROUGH TUESDAY MORNING FOR WIZ025-026-028.

&&

$$

MESOSCALE...JLT
SHORT TERM...CLF
LONG TERM...SPD
AVIATION...JLT






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