Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 282239
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
439 PM CST FRI NOV 28 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 231 PM CST FRI NOV 28 2014

WARM AIR ADVECTION FROM THE SOUTHWEST HAS PUSHED 850H TEMPS ABOVE
FREEZING FOR ALMOST ALL OF THE FA. WHILE MUCH OF THE ECHOES SEEN
ON RADAR THIS AFTERNOON WERE VIRGA...SOME VERY LIGHT PRECIP DID
MAKE IT TO THE SURFACE. AMOUNTS WERE 0.01" OR LESS...AND THAT WAS
A COMBINATION OF FREEZING DRIZZLE AND SLEET THANKS TO THE WARM AIR
ABOVE THE SURFACE. THE ONLY REMAINING PRECIP LATE THIS AFTERNOON
WAS NORTH OF THE METRO AND IN WESTERN WI. THIS SCATTERED PRECIP
WILL CONTINUE MOVING EAST THROUGH THE NEXT FEW HOURS...OTHERWISE A
DRY FORECAST THROUGH SATURDAY EVENING. THE BIG STORY AFTER THE
LIGHT MIXED PRECIP TODAY IS THE CONTINUED WARMING WITH HIGH
TEMPERATURES STILL LOOKING TO GO ABOVE FREEZING ACROSS THE AREA.
THE MODELS HAVE STRUGGLED WITH THE LOW LEVEL MOISTURE
PROFILES...AND AS INDICATED IN THE AVIATION PORTION OF THE
DISCUSSION...CONFIDENCE IN FOG AND CEILING POTENTIAL IS LOW AT
THIS TIME. AS THE WARM AIR ADVECTION CONTINUES TONIGHT...THE LOW
TO MID LEVELS WILL CONTINUE SEEING DECREASING RH VALUES AS DRIER
AIR ADVECTS NORTHEAST INTO OUR AREA. A STRONG INVERSION WILL
UNDOUBTEDLY FORM TONIGHT ACROSS THE AREA...BUT PINPOINTING HOW
MUCH MOISTURE WILL BE TRAPPED UNDER THE INVERSION AND IF IT WILL
BE ABLE TO PRODUCE EITHER LOW STRATUS OR FOG MAKES FOR A DIFFICULT
FORECAST. STILL THINKING THE FAR SOUTHERN PORTIONS OF THE FA HAVE
THE BEST SHOT AT FOG WITH WARM AIR ADVECTION MOVING OVER THE
PRESENT SNOW PACK TO HELP SATURATE THE AIR NEAR THE SURFACE...SO
AS ADVERTISED IN RECENT DAYS...EXPECTING TO SEE FOG THERE. WINDS
WILL TURN WESTERLY TOMORROW AFTERNOON AS THE ARCTIC FRONT PUSHES
THROUGH...AND SHOULD BE THROUGH MOST OF THE FA BY 00Z SUNDAY.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 231 PM CST FRI NOV 28 2014

PLUMMETING TEMPERATURES WITH DRY CONDITIONS WILL BE THE STORY FOR
THE EARLY PART OF NEXT WEEK...FOLLOWED BY MODERATING TEMPERATURES
AND CONTINUED DRY CONDITIONS FOR THE LATTER HALF OF THE WEEK.

A POTENT CDFNT STRETCHING BETWEEN TWO SEPARATING LOW PRES CENTERS
- ONE MOVING EWD ALONG THE INTERNATIONAL BORDER INTO SERN CANADA
AND A SECOND MEANDERING OVER THE CENTRAL PLAINS - WILL PUSH THRU
THE REGION SAT NIGHT. BECAUSE THE ENERGY BETWEEN THE LOW PRES
CENTERS WILL BECOME MORE STRETCHED OUT AND WEAKENED...LESS FORCING
WILL BE AVAILABLE FOR ANY PRECIP PRODUCTION SO HAVE BEEN ABLE TO
REMOVE POPS FROM THE FCST. ARCTIC HIGH PRES FOLLOWING THE CDFNT
WILL RESULT IN MUCH COLDER TEMPERATURES FOR SUN THRU MON NIGHT.
HIGHS WILL FALL TO THE TEENS ON SUNDAY AND TO THE SINGLE DIGITS
AREA-WIDE ON MONDAY DESPITE MOSTLY CLEAR SKIES AS COLD AIR
ADVECTION WILL BE VERY STRONG. HIGH PRES SHIFTING EWD BY TUE WILL
ALLOW FOR A GRADUAL MODERATING TREND THRU THE LATTER HALF OF THE
WEEK AS FLOW ALOFT WILL BECOME MORE ZONAL WHILE MORE PREVALENT
LLVL SLY COMPONENTS DEVELOP. THE PROGRESSIVE FLOW DOES LOOK TO
ALLOW ANOTHER FRONTAL SYSTEM TO SLIP THRU THE REGION TUE INTO
WED...BUT THIS SYSTEM ALSO APPEARS TOO STRIATED AND WEAK TO
PRODUCE PRECIP SO HAVE MAINTAINED A DRY FCST. HIGH PRES THEN
RETURNS WED-FRI TO KEEP A PRECIP-FREE FCST GOING. HIGHS WILL
SLOWLY WARM THRU THE 20S BUT AM NOT LOOKING TO HAVE ANY PERIODS
REACH THE FREEZING MARK THROUGH THIS EXTENDED FCST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1148 AM CST FRI NOV 28 2014

PRIMARY CONCERN IS THE NEXT 6 HOURS DEALING WITH FREEZING DRIZZLE
POTENTIAL ACROSS THE AREA.

LOW CONFIDENCE IN THE FORECAST OVERALL..ESPECIALLY TONIGHT AND
TOMORROW MORNING. THE NAM HAS OVERDONE ITS MOISTURE ANALYSIS AND
IS AFFECTING ITS PROFILES THROUGH TONIGHT. STARTING OFF...A BATCH
OF MOSTLY FREEZING DRIZZLE/RAIN IS MOVING WEST TO EAST ACROSS THE
FA EARLY THIS AFTERNOON. THANKFULLY...THE REFLECTIVITY RETURNS
CURRENTLY ON RADAR SHOW A DECENT AMOUNT OF VIRGA IN SOME
SPOTS...ESPECIALLY FAR SOUTHERN MN. IN ADDITION...THE PRECIP THAT
IS REACHING THE GROUND WILL NOT LAST VERY LONG...SO AMOUNTS SHOULD
BE VERY LIGHT. THIS AREA WILL CONTINUE WORKING EAST ACROSS THE
AREA.

IN TERMS OF CLOUD COVER AND FOG POTENTIAL...I QUESTION NAM
SOUNDING MOISTURE SIMILAR TO THE PREVIOUS SHIFT. CONSIDERING THE
SUITE OF GUIDANCE AT HAND HOWEVER...ITS CLEAR THAT LOW LEVEL
SOUTHWESTERLY FLOW WILL CONTINUE TO USHER IN WARMER AND DRIER AIR
TO THE FA. THE BIG QUESTION IS WHAT HAPPENS NEAR THE SURFACE AS
THE INVERSION STRENGTHENS. CURRENT FORECAST CALLS FOR ENOUGH
MOISTURE TRAPPING TO ALLOW MVFR OR IFR CIGS TO REMAIN IN PLACE.
HRRR INDICATES LOW STRATUS BECOMING TRAPPED UNDER THE DRYING
OCCURRING ABOVE 900-850H...SO INDICATED THE POTENTIAL FOR
RESTRICTIONS THROUGH MUCH OF TOMORROW.

KMSP...THIS IS AN EVOLVING FORECAST SITUATION. BOUTS OF FZDZ
APPEAR MORE LIKELY FROM 19-21Z HAS AS BEEN OBSERVED UPSTREAM OF
MSP. OTHERWISE...WE CONTINUE TO LINGER ON THE EDGE OF VFR TO THE
WEST. STILL...EXPECTING THE CIGS TO PERSIST THROUGH THE AFTERNOON.
CONFIDENCE IN THE CEILING FORECAST BEYOND 00Z IS QUITE LOW.
SOUTHWESTERLY DRY AIR ADVECTION COULD PREVENT RESTRICTIONS
TONIGHT...BUT WENT WITH A MORE PESSIMISTIC FORECAST BECAUSE THE
STRENGTH OF THE INVERSION LENDS ME TO BELIEVE WE`LL GET ENOUGH
MOISTURE TRAPPED BELOW IT TO CAUSE PROBLEMS.

/OUTLOOK FOR KMSP/
SUN NIGHT...VFR. WINDS NW AT 15G25KTS.
MON...VFR. WINDS NW AT 5-10KTS...BECOMING S LATE.
TUE...VFR. WINDS S AT 15G20KTS...BECOMING W.

&&

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

$$

SHORT TERM...SPD
LONG TERM...JPC
AVIATION...SPD





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