Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 212355
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
555 PM CST FRI NOV 21 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 422 PM CST FRI NOV 21 2014

THERE ARE A COUPLE FORECAST CHALLENGES OVER THE NEXT FEW DAYS. THE
FIRST: IS THE SLIGHT CHANCE FOR LIGHT FREEZING RAIN OR FREEZING
DRIZZLE IN FAR EASTERN MN AND WEST CENTRAL WI TONIGHT. THE SECOND:
IS THE MIXED P-TYPE AND WIND EVENT SUNDAY INTO MONDAY.

THERE HAS BEEN A STEADY STREAM OF HIGH CLOUDS TODAY...BUT THERE IS A
LOW STRATUS DECK STREAMING NORTH ACROSS SOUTHERN NE/IA THIS
AFTERNOON. THESE CLOUDS ARE TIED TO LOW LEVEL MOISTURE ADVECTION OUT
AHEAD OF AN ADVANCING SHORTWAVE CURRENTLY TRANSVERSE THE NORTHERN
PLAINS THIS AFTERNOON. WE THINK THERE WILL BE DEEPER SATURATION AND
BETTER OMEGA TO THE SOUTH AND WEST OF THE FORECAST AREA THIS EVENING
AND TONIGHT /BASICALLY INN AREAS CURRENTLY UNDER A FREEZING RAIN
ADVISORY/. THE SREF PROBABILITIES OF FREEZING RAIN/DRIZZLE ARE ON
THE ORDER OF 40-80% IN THESE AREAS. LOCALLY...WE`RE NOT CONFIDENT IN
MUCH ELSE BESIDES A HEALTHY STRATUS DECK AND PERHAPS SOME LIGHT FOG
AS THE STRATUS LOWERS. WE MAINTAINED LOW PROBS OF PRECIP IN EASTERN
PORTIONS OF THE FORECAST AREA WITH A MIX...AND IT ONLY TAKES A SMALL
AMOUNT OF FREEZING RAIN/DRIZZLE TO CAUSE PROBLEMS...BUT AS OF RIGHT
NOW THE BETTER LIFT AND DEEPER MOISTURE IS SOUTHEAST OF THE FORECAST
AREA. WE FOLLOWED THE LATEST REFLECTIVITY TRENDS OF THE HRRR...WHICH
MATCH UP REASONABLY WELL WITH THE 0.5KM CONDENSATION PRESSURE
DEFICITS OFF THE 20Z-22Z RAP.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 422 PM CST FRI NOV 21 2014

SPLIT FLOW WILL KEEP THE AREA LARGELY DRY INTO SUNDAY AFTERNOON
AS THE SOUTHERN STREAM LIFTS A TROUGH NORTHWARD FROM THE SOUTHERN
PLAINS INTO THE MID MISSISSIPPI VALLEY ON SUNDAY WHILE A TROUGH
DIGS INTO THE NORTHERN HIGH PLAINS ALONG THE NORTHERN STREAM.
THE NEXT MOIST SURGE MOVES IN WITH A STRONG WARM FRONT SATURDAY
EVENING AND OVERNIGHT. MODEL SIGNALS OF WARM FRONTAL
LIFT...850MB MOISTURE TRANSPORT CONVERGENCE...AND MOISTURE
ADVECTION INDICATE A FAIRLY HIGH LIKELIHOOD OF RAIN...PROBABLY
HIGHER THAN GUIDANCE INDICATES. AT THIS TIME...IT APPEARS THE
MODEL CONSENSUS AGREES THAT ONLY MINOR PRECIPITATION WOULD GO INTO
SNOW SUNDAY NIGHT AS COLDER AIR MOVES IN. THE FORECAST
SOUNDINGS...ESPECIALLY OFF THE NAM SHOW 35-40KTS AT THE TOP OF THE
MIXED LAYER WITH STEEP LOW LEVEL LAPSE RATES FOR 12-15 HOURS
SUNDAY NIGHT AND MONDAY. THE CONDITION OF THE SNOWPACK WILL BE IN
QUESTION IN THE EAST WITH THE SLIGHTLY WARMER TEMPS AND CHANCE FOR
RAIN...BUT WESTERN MN WILL REMAIN MUCH COOLER AND WE COULD ALSO
PICK UP A HIGH RATIO 0.5-2.0" IN SPOTS...SO THE THREAT FOR BLOWING
SNOW IS STILL A CONCERN IN WESTERN MN. WINTER HEADLINES ARE STILL
POSSIBLE FOR THIS PERIOD. ANOTHER COLD PERIOD BEGINS MONDAY AND
CURRENT THANKSGIVING HIGHS ARE IN THE TEENS AS A COLD AIR MASS
SETTLES IN AFTER A WEAK SYSTEM WEDNESDAY. THIS AIR MASS IN THE
NAEFS AND GEFS IS ABOUT 2 STANDARD DEVIATIONS BELOW NORMAL FOR
THURSDAY. THE OPERATIONAL RUNS ARE ALSO QUITE COLD.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 533 PM CST FRI NOV 21 2014

VFR CONDITIONS ARE CURRENTLY PRESENT AT ALL TERMINALS UNDER BROKEN
MID-HIGH LEVEL CLOUDS. OVER THE NEXT FEW HOURS THOUGH...CONTINUED
WARM ADVECTION SHOULD BRING A LOW STRATUS DECK INTO AT LEAST THE
SOUTHEASTERN HALF OF OUR AREA...AFFECTING EAU...RNH...AND MSP.
IFR/BORDERLINE LIFR CIGS ARE LIKELY AT THESE LOCATIONS OVERNIGHT
DUE TO THE LOW CLOUD DECK...WITH FOG NOT OUT OF THE QUESTION.
NORTHWESTERN TERMINALS COULD SEE SOME LOW STRATUS AS WELL BUT
CONFIDENCE IS LOWER AT THIS TIME. THIS PATTERN SHOULD PERSIST
THROUGH THE DAY...AS CONTINUED ADVECTION OF WARM MOIST AIR OVER
THE SNOWPACK SHOULD KEEP LOW CLOUDS AND IFR CIGS PRESENT THROUGH
SATURDAY AFTERNOON. SOME DRIZZLE IS ALSO POSSIBLE IN WESTERN WI
AND EASTERN MN...BUT CHANCES ARE TOO LOW TO WARRANT MENTIONING IN
THE TAFS AT THIS TIME.

KMSP...MOST GUIDANCE SHOWS A LOW STRATUS DECK MOVING IN A FEW
HOURS AFTER SUNSET WITH CIGS CONTINUING TO LOWER OVERNIGHT. PRECIP
SHOULD REMAIN TO THE SOUTHEAST OVERNIGHT WITH SOME PATCHY DRIZZLE
POSSIBLE SATURDAY...THOUGH CHANCES OF PRECIPITATION REMAIN LOW.

/OUTLOOK FOR KMSP/
SAT NIGHT...IFR LIKELY. WINDS SSW 10G20 KT.
SUN...MVFR/IFR WITH FZDZ/-RA POSSIBLE. WINDS SE 10 KT.
MON...MVFR/IFR WITH -SN/BLSN POSSIBLE. WINDS NW 25G30 KT.

&&

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

$$

SHORT TERM...CLF
LONG TERM...CLF
AVIATION...ADL





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