Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 161829
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
129 PM CDT SAT AUG 16 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 422 AM CDT SAT AUG 16 2014

ALTHOUGH WIDELY SCATTERED IN NATURE...A FEW AFTERNOON SHOWERS AND
THUNDERSTORMS HAVE THE POTENTIAL TO PRODUCE LOCALLY HEAVY RAINFALL
AMOUNTS. EARLY MORNING SURFACE ANALYSIS IDENTIFIED A WEAK COLD
FRONT LOCATED TO THE NORTH ALONG THE INTERNATIONAL BORDER.
MEANWHILE LOW LEVEL MOISTURE CONTINUE TO ENCROACH FROM THE
SOUTH...WITH LOW STRATUS SPILLING UP FROM NORTHERN IA INTO
SOUTHERN MN.

OVER THE NET 12 TO 24 HOURS...THE STRATUS SHOULD MIX OUT WITH
FORECAST SOUNDINGS SHOWING AN UNCAPPED ENVIRONMENT BY DURING THE
AFTERNOON WITH 1000 TO 2000 J/KG OF CAPE. WEAK CONVERGENCE ALONG THE
SAGGING FRONTAL BOUNDARY SHOULD RESULT IN A FEW WIDELY SCATTERED
THUNDERSTORMS ACROSS THE NORTHERN HALF OF THE CWA. THE MAIN CONCERN
WITH THESE STORMS IS THE INCREDIBLY WEAK WIND FIELD THROUGHOUT THE
TROPOPAUSE. THE BUFKIT HEAVY PRECIP PARAMETER SHOWS AROUND 2-5KTS
FOR THE MEAN WIND...LOW LEVEL JET...AND MESOBETA ELEMENTS. THIS
SHOULD LEAD TO VERY SLOW MOVING...IF NOT STATIONARY THUNDERSTORMS
WHICH WILL BE CAPABLE OF PRODUCING A QUICK 1-3...WITH POSSIBLE 4
INCHES OF RAIN OVER VERY SMALL AREAS. THIS COULD LEAD TO LOCALIZED
FLOODING...BUT AGAIN THE COVERAGE WILL BE SCARCE SO NOT ANTICIPATING
WIDESPREAD FLOODING PROBLEMS. HIRES MODELS SUPPORT THE LIMITED
COVERAGE SO DID NOT RAISE POPS MUCH FROM THE PREVIOUS FORECAST...
HOWEVER DID INCLUDE THE HEAVY RAIN MENTION IN THE WEATHER GRIDS
FOR ANY STORMS THAT DO MANAGE TO DEVELOP.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 422 AM CDT SAT AUG 16 2014

MAIN ISSUES FOR THE LONG TERM DEAL WITH SHORT WAVE DROPPING OUT OF
THE WNW SUNDAY INTO MONDAY...AND PROBABLE DEVELOPMENT OF WESTERN
TROUGH DURING THE MIDDLE TO LATTER PORTION OF NEXT WEEK.

UPPER LEVEL LOW NOW SPINNING ALONG THE IDAHO/BC BORDER. BEING
DISPLACED FROM THE FASTER FLOW NEAR 60 DEGREES NORTH IN WESTERN
CANADA... SAID UPPER LOW WILL TAKE ITS TIME GETTING HERE. LOW
MOVES ENE INTO SOUTHERN SASKATCHEWAN THEN ESE INTO NRN MN MONDAY
EVENING. NW/SE ORIENTED LOBE OF ENERGY IS FLAGGED BY ECMWF AND
GFS MOVING INTO WC/SW MN SUNDAY...THEN ACROSS MOST OF OUR AREA
SUNDAY NIGHT. LOW POPS SUNDAY INTO SUNDAY EVENING WILL BE LARGELY
DUE TO THE SURFACE HIGH TO THE NORTH OF LAKE SUPERIOR KEEPING SOMEWHAT
DRY EASTERLY FLOW ACROSS CENTRAL AND EAST CENTRAL MN INTO WISC.
BUT THIS SHOULD SATURATE QUICKLY AS SHORT WAVE ARRIVES. THERE LOOKS TO BE
PLENTY OF MOISTURE AND PRECIPITABLE WATER VALUES SHOULD BE IN THE
1.5 TO 1.7 INCH RANGE ACROSS MUCH OF THE AREA SUNDAY AND MONDAY.
WINDS WILL STILL BE RELATIVELY WEAK ALOFT LEADING TO POCKETS OF
HEAVY RAIN. MAIN ENERGY WITH SHORT WAVE FINALLY DEPARTS TUESDAY RESULTING
IN TUESDAY NIGHT AND WEDNESDAY BEING LARGELY DRY. CANNOT
COMPLETELY ELIMINATE POPS AS THERE WILL STILL BE PLENTY OF
RESIDUAL MOISTURE AND SOME INSTABILITY DESPITE WEAK RIDGING.

MODELS ARE STILL SHOWING THE OVERALL TREND OF A LARGE TROUGH
DEVELOPING IN THE WEST DURING THE MIDDLE PART OF NEXT WEEK. SOME
MAJOR DIFFERENCES STILL INCLUDE EXTENT OF CUTOFF LOW OFF
CALIFORNIA...AND IN THE STRENGTH OF UPPER RIDGE EXTENDING
NORTHWARD TOWARD MN/WI FROM THE DEEP SOUTH. THE GFS WOULD SUGGEST
THE WARMEST TEMPS BUT EVEN THE ECMWF IS TRENDING TOWARD WARMER AND
MORE HUMID THAN ITS PREVIOUS VERSIONS. BROAD SW UPPER FLOW OVER
THE AREA WILL MEAN HIGHER CHANCES OF STORMS LATE NEXT WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1246 PM CDT SAT AUG 16 2014

IFR/MVFR CEILINGS ARE STILL SLOWLY LIFTING WITH THE AFTERNOON
SUNSHINE...BUT THE CLEARING IS ALSO HELPING TO BUILD INSTABILITY
AND WE ARE SEEING ISOLATED TO SCATTERED SHOWERS FORMING NEAR A
COLD FRONT IN CENTRAL MN AND NORTHWEST WI. WE EXPECT THE COVERAGE
TO INCREASE SLIGHTLY OVER THE NEXT FEW HOURS AND THE SHOWERS
SHOULD ALSO SLOWLY MOVE SOUTH WITH TIME. AT THIS POINT...THE
COVERAGE SHOULD BE SPARSE ENOUGH THAT MOST OF THE ACTIVITY WILL
JOG AROUND THE TAF SITES...BUT A BRIEF DOWNPOUR IS POSSIBLE THIS
AFTERNOON AND AFTERNOON AND EVENING.

KMSP...

NOW THAT THE CEILING HAS LIFTED TO 2000FT /WITH FURTHER
IMPROVEMENT EXPECTED/. NO SIGNIFICANT WEATHER IMPACTS ARE EXPECTED
THROUGH THE AFTERNOON AND EARLY EVENING. THERE ARE ISOLATED
SHOWERS DEVELOPING IN CENTRAL MN...AND IT`S NOT IMPOSSIBLE THAT
THESE EVENTUALLY IMPACT KMSP EARLY THIS EVENING...HOWEVER...THE
SHOWER COVERAGE WILL REMAIN SPARSE AND WE DECIDED TO LEAVE THE
MENTION OF RAIN OUT OF THE FORECAST FOR NOW. WE THINK MSP WILL BE
CLOSE TO THE FRONT THIS EVENING AND LOW STRATUS SEEMS POSSIBLE ONE
AGAIN LATE TONIGHT.

/OUTLOOK FOR KMSP/
SUN NIGHT...VFR. MVFR WITH TSRA POSSIBLE WINDS E 5-10 KTS.
MON...VFR/MVFR WITH TSRA LIKELY AFTN/NIGHT. WINDS S 5-10 KTS.
TUE...VFR/MVFR WITH TSRA POSSIBLE. WINDS NW 5-10 KTS.

&&

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

$$

SHORT TERM...JRB
LONG TERM...TDK
AVIATION...CLF






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