Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 261204
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
704 AM CDT SUN OCT 26 2014

.UPDATE...
ISSUED AT 632 AM CDT SUN OCT 26 2014

UPDATED TO INCLUDE 12Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 244 AM CDT SUN OCT 26 2014

SFC ANALYSIS THIS MORNING SHOWS LARGE SFC HIGH PRES CENTERED OVER
THE CENTRAL GREAT LAKES...MAINTAINING ITS WRN FRINGES OVER THE UPR
MISS RIVER VALLEY...WHILE A COMPLEX AREA OF LOW PRES BECOMES MORE
ORGANIZED OVER SRN ALBERTA. THIS SFC LOW IS DEVELOPING IN ADVANCE
OF A LONGWAVE TROF MOVING ACROSS THE NRN ROCKIES AND GREAT
BASIN...AND THIS TROF TRAILS A RIDGE AXIS ALOFT THAT WILL SHIFT
ACRS MN AND WI TDA. AS THE RIDGE EXITS TO THE E...CLOUDS WILL
STEADILY INCREASE THROUGHOUT THE DAY TDA...PARTICULARLY AS A WMFNT
APPROACHES FROM THE W TDA. AN ARGUMENT CAN BE MADE THAT THE FRONT
WILL BE MORE OF AN OCCLUSION SINCE THE MAIN LOW...A NRN STREAM
LOW...WILL REMAIN WOUND UP AND N OF THE AREA WHILE A SECONDARY SRN
STREAM LOW FROM THE ROCKIES STAYS TO THE S AND KEEPS THE MORE BONA
FIDE WARM AIR TO THE S. REGARDLESS...THE EFFECTS WILL BE AN INCRS
IN CLOUD COVER BUT NOT NECESSARILY MOISTURE. 1000-500MB COLUMNS
LOOK TO REMAIN FAIRLY SHALLOW ACRS THE ENTIRE CWFA DURG THE
DAYLIGHT HRS TDA. SO DESPITE THE INCRS IN FRONTAL LIFT WITH THE
INCOMING SYSTEM...PRECIP GENERATION LOOKS MEAGER AT BEST SO HAVE
OPTED TO MAINTAIN A DRY FCST...EVEN FOR WRN WI WHERE FRONTAL LIFT
AND MOST INSTABILITY LOOK TO BE COINCIDENT. THE APPROACHING UPPER
TROUGH LOOKS TO BECOME SHARPER AND DIG DEEPER INTO THE NRN-CENTRAL
PLAINS OVERNIGHT INTO MON MRNG WHICH WILL ENHANCE LIFT WHILE
PIVOTING THE SFC LOW MOVING INTO SRN MANITOBA. MOISTURE DOES BEGIN
TO POOL TNGT OVER ERN PORTIONS OF THE CWFA...SO THIS LENDS TO
BETTER AGREEMENT OF SEEING SCATTERED SHOWERS OVER MAINLY FAR ERN
MN INTO WRN WI OVERNIGHT TNGT THRU MON MRNG. IN ADDITION...
NAM/SREF/HRRR DO DEPICT SOME MODEL INSTABILITY TO THE TUNE OF
NEARLY 1000 J/KG MUCAPE...SO HAVE MAINTAINED SLGT CHC TSTM MENTION
IN THE FCST. NOT LOOKING FOR A LOT OF COVERAGE AT ALL...BUT THE
PROSPECTS OF THUNDER CANNOT BE IGNORED SO HAVE GIVEN IT ITS DUE
DILIGENCE. AS FOR TEMPS...THE CLEAR SKIES AND LIGHT WINDS THIS
MRNG HAVE ALLOWED TEMPS TO BOTTOM OUT IN THE 30S FOR THE ENTIRE
CWFA. AMPLE SUNSHINE AND SE WINDS THRU THE FIRST HALF OF TDA WILL
ALLOW TEMPS TO REBOUND NICELY INTO THE 60-70 DEGREE RANGE...WITH
THE HIGHEST TEMPS IN WRN MN. CLOUDS TNGT AND STRONG SLY FLOW
ASSOCIATED WITH THE WARM FROPA WILL PRODUCE MUCH MORE MILD TEMPS
TNGT INTO MON MRNG. WILL LOOK FOR LOWS TO ONLY DROP TO THE UPR 40S
TO LWR 50S.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 244 AM CDT SUN OCT 26 2014

MODELS HAVE BEEN TRENDING FOR A MORE POTENT SHRTWV/UPPER LOW TO
FORM/MOVE ACROSS THE UPPER MIDWEST LATE MONDAY/TUESDAY WHICH
CORRESPONDS TO A BETTER CHC OF SHRA...ESPECIALLY TUE AS THE CORE
OF THE COLDEST AIR MOVES ACROSS THE REGION. THE ONLY CONCERN IS
THE AMT OF DEEP MOISTURE AVAILABLE DUE TO THE MAIN FRONT WELL SOUTH
OF OUR REGION. IN ADDITION...THE PHASING OF THE SOUTHERN/NORTHERN
JET REMAINS QUESTIONABLE...ESPECIALLY EARLY IN THE PERIOD...WITH A
BETTER CHC OF THE SOUTHERN STREAM HAVING MORE INFLUENCE ON
DEEPER MOISTURE/CONVECTION. THERE REMAINS ENOUGH CONFIDENCE FOR
SCATTERED/ISOLD SHRA FOR MONDAY...ESPECIALLY DURING THE AFTN...AND
AGAIN TUESDAY AFTN AS THE UPPER LOW MOVES NEAR THE REGION.

PAST TUESDAY...PRECIPITATION CHC/S REMAIN LOW CONSIDERING THE MUCH
DRIER AIR MASS REPLACING TUESDAY/S SYSTEM AND THE HIGH AMPLITUDE
OF UPPER RIDGE FORECAST TO BUILD ACROSS THE ROCKIES LATE IN THE
WEEK. IN OUR REGION...THIS AMPLIFIED PATTERN WILL LEAD TO A SHARP
CONTRAST FROM THE GREAT LAKES/OHIO VALLEY TO THE HIGH PLAINS AND
THE ROCKIES BY NEXT WEEKEND. IT IS LIKELY THAT THE COLDEST AIR OF
THE SEASON WILL SURGE SOUTHWARD THU/FRI AS THIS AMPLIFIED PATTERN
DEVELOPS. DEPENDING UPON THE STRENGTH OF THE LONG WAVE TROUGH IN
THE EASTERN U.S. AND HOW IT BECOMES BLOCKED IN THE OVERALL
PATTERN...WILL DETERMINE WHEN THE WARMER AIR REBOUNDS ACROSS THE
UPPER MIDWEST THE FIRST WEEK OF NOVEMBER.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 632 AM CDT SUN OCT 26 2014

VFR THRU THIS AFTN AS HIGH PRES SHIFTS OFF TO THE E.
WMFNT/OCCLUSION WILL APPROACH FROM THE W THIS EVE...SLOWLY
CROSSING OVER THE AREA OVERNIGHT INTO MON MRNG. CLOUDS WILL
STEADILY INCRS FROM THE W TDA INTO TNGT...STARTING OUT AS HIGH CI
THEN GRADUALLY LOWERING AND FORMING BKN/OVC DECKS. AS FOR -SHRA
POTENTIAL THIS EVE AND TONIGHT...BEST LIFT AND DEEPEST MOISTURE
WILL BE OVER ERN PORTIONS OF THE COVERAGE AREA...MAKING HIGHEST
PRECIP CHCS OVER THE WI TAF SITES AND KMSP ON THE FRINGE WITH NO
PRECIP XPCTD FOR KSTC-KAXN-KRWF. HAVE OPTED ATTM TO OMIT ANY CB/TS
MENTION SINCE CHCS/CONFIDENCE FOR CONVECTION ARE VERY LOW. WINDS
WILL GENERALLY COME FROM THE SE TDA...INCRG TO NEAR 15 KT BEFORE
SETTLING DOWN THIS EVE. WRN TAF SITES WILL SEE A SWING IN WINDS
TNGT INTO TMRW AS SE TO SW THEN W...AND IN A RELATIVELY SHORT TIME
SPAN OVERNIGHT. ERN TAF SITES WILL GENERALLY REMAIN SE WITH LESSER
SPEEDS.

KMSP...VFR THRU THIS EVE WITH GRADUALLY INCREASING/LOWERING
CLOUDS. PRECIP DEVELOPING OVER WRN WI THIS EVE AND TNGT MAY JUST
SPREAD WWD ENOUGH TO INCLUDE KMSP SO HAVE OPTED TO USE A PROB30 TO
EXPRESS THIS UNCERTAINTY. BEST TIMING WOULD BE LATE EVE TO EARLY
MRNG HRS. GOING INTO THE EARLY MRNG HRS THRU DAYBREAK MON MRNG...
MVFR CEILINGS LOOK HIGHLY LIKELY...BUT NOTHING BELOW 2000FT XPCTD.
IN ADDITION...WIND SPEEDS WILL DROP OFF TO 3-5 KT OVERNIGHT THRU
DAYBREAK WHILE WINDS WILL VEER ARND FROM SE TO SW TO W. TIMING THE
SHIFTS IS TRICKY ATTM...AND WITH SPEEDS DROPPING OFF TO THE LOWER
SPEEDS...HAVE OPTED TO USE VRB04KT TO HANDLE THE WIND SHIFT RATHER
THAN TRYING TO GET FANCY WITH PINPOINTING THE TIMING/DIRECTIONS.
THESE CAN BE BETTER REFINED IN LATER TAF ISSUANCES.

/OUTLOOK FOR KMSP/
TUE...MAINLY VFR. SLGT CHC -SHRA. WINDS W 10-15 KT.
WED...VFR. WINDS W 5-10 KT...BECMG S.
THU...VFR. WINDS N 5-10 KT.

&&

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

$$

UPDATE...JPC
SHORT TERM...JPC
LONG TERM...JLT
AVIATION...JPC






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