Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 170327
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1027 PM CDT THU APR 16 2015

.UPDATE...


&&

.AVIATION/06Z TAFS/...

MAINLY VFR CONDITIONS WITH WEAK HIGH PRESSURE TO THE SOUTH OF THE
STATE. PATCHY IFR IN RIVER VALLEYS...ESPECIALLY IN THE EAST WHERE
MARINE AIR IS A BIT MORE MOIST. EXPECT A LAKE BREEZE OFF LAKE
MICHIGAN AGAIN FRIDAY LATE MORNING/AFTERNOON. WITH THE HIGH TO
THE SOUTH...BLENDED GUIDANCE SUGGESTS LAKE BREEZE WILL REMAIN
OFFSHORE UNTIL AROUND 16Z...AT WHICH POINT IT WILL IMPACT
LAKESHORE SITES...AND MOVING TO UES BY 21Z. SCATTERED AFTERNOON
CUMULUS AROUND 6 THSD FT...EXCEPT NEAR LAKE MICHIGAN DURING THE
AFTERNOON.

&&

.PREV DISCUSSION... /ISSUED 332 PM CDT THU APR 16 2015/

SHORT TERM...

TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.

HIGH PRESSURE HAS BUILT IN SOUTH OF THE STATE WITH MOSTLY ZONAL FLOW
ALOFT. ADDITIONALLY...THE DEPTH OF THE ATMOSPHERE WILL REMAIN DRY
THROUGH AT LEAST TOMORROW AFTERNOON FOR MUCH OF THE AREA. THE HIGH
PRESSURE/ZONAL PATTERN ALOFT AND THE LACK OF MOISTURE IN THE
ATMOSPHERE SHOULD COMBINE FOR MOSTLY CLEAR SKIES UNTIL TOMORROW
AFTERNOON...WHEN SOME DIURNAL CU ARE LIKELY. THE GFS AND NAM SUGGEST
SOME LATE AFTERNOON SHOWERS...AND PERHAPS A THUNDERSTORM OR
TWO...BUT AT THIS POINT HAVE LITTLE CONFIDENCE THIS WILL HAPPEN...SO
KEPT POPS LOW THROUGHOUT THE PERIOD.

THE PRIMARY CONCERNS WITH THIS FORECAST ARE THE TIMING OF THE LAKE
BREEZE AND TEMPERATURES. THE WEAK HIGH TO OUR SOUTH SHOULD KEEP THE
LAKE BREEZE OFFSHORE INTO THE EARLY AFTERNOON HOURS. THIS SHOULD
ALLOW TEMPERATURES ALONG THE LAKESHORE TO REACH NEAR 60.
INLAND...MUCH OF THE HIGH RES GUIDANCE...ESPECIALLY THE BIAS
CORRECTED GUIDANCE...SUGGESTS TEMPERATURES REACHING INTO THE HIGH
70S. 925 TEMPS SUPPORT HIGH 70S...ESPECIALLY WEST...SO ADJUSTED
FORECAST HIGHS TO MATCH. DEPENDING ON HOW MUCH CLOUD COVER BUILDS
IN...HIGH TEMPS MAY NEED TO BE ADJUSTED EVEN HIGHER.

FRIDAY NIGHT AND SATURDAY...FORECAST CONFIDENCE IS MEDIUM

THE NAM AND GFS ARE PROGGING A BRIEF PERIOD OF QPF ALONG A
BAROCLINIC ZONE DRAPED ACROSS THE FORECAST AREA. HOWEVER...THE
ECMWF MODEL IS GOING DRY. FORCING LOOKS VERY WEAK WITH THE GFS
SHOWING EXTREMELY WEAK Q-VECTOR CONVERGENCE AND A LACK OF A LOW
LEVEL BAROCLINIC ZONE...ALONG WITH NAM MODEL SOUNDINGS SHOWING DRY
LOW LEVEL CONDITIONS. DECIDED NOT TO PUT ANY POPS IN GRIDS FOR LATE
FRIDAY/EARLY SATURDAY DUE TO EVIDENCE AGAINST CHANCES OF
PRECIPITATION. CONDITIONS SHOULD REMAIN DRY THROUGH LATE SATURDAY
UNTIL AN AREA OF LOW PRESSURE TRANSLATES INTO THE UPPER MIDWEST
REGION.

LONG TERM...

SUNDAY AND MONDAY...FORECAST CONFIDENCE IS HIGH

A STRENGTHENING 130 KT UPPER LEVEL JET STEAK OVER SOUTHERN CANADA
WILL PROVIDE UPPER LEVEL DIVERGENT FLOW OVER THE REGION...ALONG WITH
A POTENT MID LEVEL SHORTWAVE TROUGH WITH ISENTROPIC OMEGA WITH
VALUES OVER -30 UBAR/S...SUPPORTING AN EXTENDED PERIOD OF
PRECIPITATION ACROSS OUR FORECAST AREA. GFS AND ECMWF MODELS ARE IN
SOME DISAGREEMENT WITH THE NAME AS TO THE TIMING OF THE INITIAL
PRECIPITATION BAND...BUT IT LOOKS LIKE PRECIPITATION WILL BEGIN
EARLY SUNDAY MORNING AND LAST THROUGH THE DAY MONDAY. NAM BUFKIT
SOUNDINGS ARE SHOWING THE POTENTIAL FOR SOME THUNDERSTORMS DURING
THE DAY SUNDAY AS ELEVATED CAPE OF NEARLY 100 J/KG DOES EXIST.
MODERATE RAIN SHOWERS APPEARS LIKELY WITH THIS SYSTEM.

MONDAY NIGHT THROUGH THURSDAY...FORECAST CONFIDENCE IS MEDIUM

THE LARGE SCALE SYSTEM SHOULD MOVE OUT BY MONDAY NIGHT/TUESDAY
MORNING. MODELS SHOW DRIER CONDITIONS EARLY TUESDAY. MODELS ARE
SHOWING THE POTENTIAL FOR SOME RESIDUAL MOISTURE STICKING AROUND
TUESDAY AFTERNOON. THE OTHER BIG STORY IS A COOL DOWN FOR THE
WEEK...AS LOW TEMPERATURES WILL BE IN THE LOWER 30S TUESDAY THROUGH
THURSDAY. ANOTHER LOW PRESSURE TROUGH LOOKS TO BE SWING THROUGH THE
REGION WEDNESDAY MORNING...KEEPING CHANCES OF PRECIPITATION IN THE
FORECAST AREA INTO THURSDAY.

AVIATION/00Z TAFS/...WITH WEAK HIGH PRESSURE TO THE SOUTH OF THE
STATE...WILL REMAIN IN VFR THROUGHOUT THE PERIOD WITH RELATIVELY
LIGHT WINDS. THE ONLY CONCERN IS THE TIMING OF THE LAKE BREEZE. WITH
THE HIGH TO THE SOUTH...BLENDED GUIDANCE SUGGESTS LAKE BREEZE WILL
REMAIN OFFSHORE UNTIL AROUND 18Z...AT WHICH POINT IT WILL IMPACT
LAKESHORE SITES...AND MOVING TO UES BY 21Z. THAT SAID...WOULD NOT BE
SURPRISED TO SEE LAKEBREEZE COME ONSHORE AN HOUR OR TWO LATER OR
EARLIER THAN FORECASTED IN TAFS.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&

$$

UPDATE...HENTZ
TONIGHT/FRIDAY AND AVIATION/MARINE...BSH
FRIDAY NIGHT THROUGH THURSDAY...JTS


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