Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 220537
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1137 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 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1046 PM CST FRI NOV 21 2014

LOW CLOUDS ARE CURRENTLY BEING ADVECTED NORTHWARD THROUGH SOUTHEAST
MN AND WESTERN WI.  THIS STRATUS DECK WILL CONTINUE TO OVERSPREAD
EASTERN TERMINALS...WHERE IFR CIGS WILL DEVELOP WITHIN THE NEXT
COUPLE HOURS. THE LOW STRATUS DECK OVER EASTERN TERMINALS SHOULD
BUILD NORTHWESTWARD BY SATURDAY MORNING...AND IFR/LIFR CIGS COULD
DEVELOP OVER ALL TERMINALS BY THIS TIME. THE POTENTIAL FOR PATCHY
FOG ALSO EXISTS...AS THE HRRR AND HOPWRF SHOW VISIBILITIES LESS THAN
A MILE ACROSS THE REGION SATURDAY MORNING. WHILE THERE IS STILL SOME
DISAGREEMENT...MOST MODELS SHOW THE POTENTIAL FOR A PROLONGED PERIOD
OF IFR/LIFR CIGS AT ALL TERMINALS THROUGH SATURDAY EVENING AS WARM
MOIST AIR IS ADVECTED OVER THE SNOW PACK.

KMSP...IFR CIGS WILL DEVELOP WITHIN THE NEXT COUPLE HOURS AS A LOW
CLOUD DECK DEVELOPS. IFR/LIFR CIGS AND REDUCED VISIBILITIES ARE
LIKELY SATURDAY MORNING THROUGH THE EVENING AS LOW CLOUDS AND
POSSIBLY PATCHY FOG PERSIST. MEASURABLE PRECIP SHOULD REMAIN TO THE
SOUTHEAST ON SATURDAY WITH SOME PATCHY DRIZZLE POSSIBLE IN THE
EVENING...THOUGH CHANCES OF PRECIPITATION REMAIN LOW.

/OUTLOOK FOR KMSP/
SUN...MVFR/IFR WITH FZDZ/-RA POSSIBLE. WINDS SE 10 KT.
MON...MVFR/IFR WITH -SN/BLSN POSSIBLE. WINDS NW 25G30 KT.
TUES...VFR/MVFR WITH -SN POSSIBLE EARLY. WINDS NW 10 KT.

&&

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

$$

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





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