Special Weather Statement, NWS Twin Cities, MN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1221 PM CDT FRI MAY 31 2013

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 330 AM CDT FRI MAY 31 2013

EARLY MORNING WATER VAPOR IMAGERY TOGETHER WITH THE PRESSURE OF THE
1.5PVU SURFACE SHOWED A NARROW RIBBON OF POTENTIAL VORTICITY
PROTRUDING DOWN TO THE 450/500MB LEVEL. THIS PV RESERVOIR
ORIGINATED UPSTREAM OFF THE BRITISH COLUMBIA COAST...EXTENDED
SOUTHEAST ACROSS THE KS/NE BORDER...AND CURLED UP OVER THE UPPER
MIDWEST. OVERLAYING THE 300MB WINDS SHOWED AN AREA OF POSITIVE
VORTICITY OWING TO THE EASTERLY WINDS OF 30KTS ON THE POLEWARD SIDE
OF +100KT WESTERLY JET. AT THE SURFACE A 991 LOW WAS LOCATED BENEATH
THE LEADING EDGE OF THE PV GRADIENT ALONG THE SD/ND BORDER...WITH A
SURFACE COLD FRONT DRAPED ON THE EASTERN SIDE OF THE MISSOURI
RIVER VALLEY.

FOR TODAY THE 00Z RUN OF THE HOPWRF AND FEW RUNS OF
THE HRRR SHOWS ANOTHER ACTIVE DAY SOUTH AND EAST OF THE CWA WITH
SEVERAL THUNDERSTORM COMPLEXES EXPECTED TO DEVELOP AS THE DEEP SHEAR
ASSOCIATED WITH THE AFOREMENTIONED UPPER LEVEL JET MOVE ACROSS THE
MISSISSIPPI RIVER VALLEY. MEANWHILE IT SHOULD BE MAINLY DRY FOR THE
FIRST HALF OF FRIDAY ACROSS THE CWA. IN FACT FORECAST SOUNDINGS VIA
THE RAP SUPPORT MOSTLY SUNNY SKIES DURING THE MORNING HOURS.
HOWEVER...WITH THE VORT MAX ROTATING OVERHEAD EXPECT INCREASING
CLOUDS WITH SHOWERS/THUNDERSTORMS AS THE ATMOSPHERE DESTABILIZES BY
MID AFTERNOON...MORE SO THAN THE HIRES MODELS WOULD INDICATE. THE
BEST DEEP LAYER SHEAR WILL BE ACROSS EASTERN IOWA AND WISCONSIN...SO
SEVERE THREAT IS LOW IN MINNESOTA...BUT COULD SEE SOME STRONGER
STORMS IN WEST CENTRAL WISCONSIN. BUFR FORECAST SOUNDINGS SHOW
ROUGHLY 1000J/KG OF MLCAPE AND FREEZING LEVELS AROUND 9-10KFT
AGL...SO WOULD NOT BE SURPRISED TO GET SOME SMALL HAIL AND GUSTY
WINDS WITH A FEW OF THE STRONGER CELLS. THE BEST CHANCE FOR DEEPER
CONVECTION WILL BE IN EASTERN MN AND WESTERN WI. ON FRIDAY NIGHT
THE INSTABILITY WILL DECREASE GIVING WAY TO LIGHT WINDS AND LOW
STRATUS AS THE OCCLUDED CYCLONE SLOWLY WOBBLES EASTWARD. A FEW
LIGHT RAIN SHOWERS DEVELOP ACROSS THE WESTERN HALF OF THE CWA AS
INDICATED BY THE LOW LEVEL SATURATION SHOWN IN THE BUFR SOUNDINGS.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 330 AM CDT FRI MAY 31 2013

CLOSED UPPER CIRCULATION OVER THE REGION SATURDAY. IT SHOULD
PROVIDE GENERAL CLOUDINESS AND THE THREAT OF SHOWERS MUCH OF THE
DAY. AS THE CIRCULATION PIVOTS EAST NORTHEAST AND WEAKENS...MODELS
SUGGEST SOME WEAK SURFACE BASED CAPE AND SOME SLIGHTLY NEGATIVE
BEST LI'S OVER EASTERN AREAS...INTO THE AFTERNOON. WILL NEED SOME
BREAKS IN THE CLOUDS TO GENERATE ANY SIGNIFICANT DESTABILIZATION.
OPTED TO MENTION ISOLATED THUNDER OVER THE EAST PORTION OF THE
CWA...MAINLY IN THE AFTERNOON. WITH SIGNIFICANT CLOUD COVER
AROUND...TEMPERATURES MAY NOT GET OUT OF THE 50S OVER THE WEST AND
WILL REMAIN IN THE 60S EAST.

THIS INITIAL SYSTEM MOVES EAST...AND BECOMES MORE PROGRESSIVE AS
THE NEXT SIGNIFICANT TROUGH MOVES ASHORE OVER THE PACIFIC
NORTHWEST LATER SUNDAY. THIS SHOULD PROVIDE A CLEARING
TREND...ALONG WITH DRIER CONDITIONS SUNDAY INTO MONDAY. SOME
RETURN FLOW...WARM AIR ADVECTION PATTERN DEVELOPS DURING THE DAY
MONDAY...MAINLY OVER THE FAR WEST. THE WESTERN CLOSED CIRCULATION
MOVES SLOWLY EAST OVER THE REGION...AND APPEARS TO AFFECT THE AREA
FOR THE REMAINDER OF THE WEEK. THIS WILL AGAIN PROVIDE A LONG
PERIOD OF CLOUDINESS AND THE THREAT OF SHOWERS AND THUNDERSTORMS
TO THE CWA. TUESDAY AND WEDNESDAY LOOK TO BE THE WETTEST DAYS...BUT
THE SHOWERY WEATHER PATTERN WILL CONTINUE THROUGH THURSDAY. THE
BELOW NORMAL TEMPERATURE PATTERN WILL ALSO CONTINUE INTO THE
FIRST PART OF JUNE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1205 PM CDT FRI MAY 31 2013

SHRA HAVE ALREADY DEVELOPED IN SE MN AHEAD OF A STRONG SHRTWV
ACROSS WESTERN IOWA. BEST INSTABILITY AND SHEAR WILL REMAIN EAST
OF THE FA...BUT RNH/MSP/EAU DO HAVE THE POTENTIAL OF GETTING
STRONGER STORMS AS EARLY AS 1-2 PM. EAU HAS THE BEST POTENTIAL OF
SVR WIND GUSTS AND LARGE HAIL BEFORE 1Z/01. ACROSS WESTERN MN...THE
UPPER LOW HAS NEARLY STALLED. BUT THIS LOW IS EXPECT TO SLOWLY
FILL AND MOVE TO THE E-NE OVER THE NEXT DAY OR SO. IFR/MVFR CIGS
WITH SCATTERED SHRA WILL OCCUR NEAR AND UNDER THIS LOW PRESSURE
SYSTEM...WITH THE BEST POTENTIAL OF -SHRA OCCURRING DURING THE
TYPICAL MID AFTN...TO LATE EVENING HRS AS INSTABILITY WILL BE THE
GREATEST. MVFR CIGS THIS AFTN WILL LIKELY RISE TO LOW END VFR IN
WESTERN MN...BUT LOWER ONCE AGAIN DURING THE EVENING AS THE LOW
TRACKS E-NE ACROSS THE NORTHERN FA. TIMING OF THE INITIAL TSRA
DEVELOPMENT ACROSS FAR EASTERN MN/WC WI WILL BE DEPENDENT ON WHEN
THE WEAKENING CAP BREAKS. AS PREVIOUSLY STATED...TSRA COULD
DEVELOP AS EARLY AS 1-2 PM BASED ON THE LATEST MESOSCALE MODEL
RUNS. SFC WINDS WILL BE STRONGEST THRU 21Z...THEN DECREASE AND
BECOMING LIGHT AND VARIABLE OVERNIGHT. ONCE THE LOW MOVES TO THE
EAST...WINDS WILL SHIFT TO THE SW/W...AND EVENTUALLY NW AND
INCREASE IN SPD.

KMSP...

BEST TIME FRAME FOR TSRA/SHRA WILL OCCUR BETWEEN 19-22Z...WITH
ONLY SHRA AFT 22Z. ANY TSRA THAT DUE DEVELOP HAVE THE CAPABILITY
OF PRODUCING VERY GUSTY WINDS UP TO 40 KTS...AND SMALL HAIL. WILL
MONITOR THE POTENTIAL OF AN AWW IF NEEDED. THIS EVENING WILL BE
VFR WITH WINDS DECREASE AND SHIFTING TO THE SW UNDER 6 KTS. BY
12-15Z...WINDS WILL SHIFT TO THE W...AND NW AND INCREASE DURING
THE AFTN. -SHRA WILL BE POSSIBLE ANY TIME AFT 15Z/01 AS THE SFC
LOW MOVES NORTH OF THE AIRPORT TERMINAL. VFR CIGS WILL LIKELY FALL
TO MVFR AS THE LOW MOVES CLOSER TO THE AIRPORT SITE OVERNIGHT.

/OUTLOOK FOR KMSP/

SAT EVENING...MVFR WITH -SHRA. WINDS NW AT 10G20KTS.
SUN...VFR. WINDS NNW AT 10KTS.
MON...VFR WITH -SHRA POSSIBLE LATE. WINDS ESE AT 10KTS.

&&

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

SHORT TERM...JRB
LONG TERM...DWE
AVIATION...JLT

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>